We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is a...We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is accomplished by using a new well-designed cryogenic experimental system suitable for a pulsed-laser platform.Firstly,when the temperature drops from+20℃to-140℃,the increased carrier mobility drives a slight increase in transient amplitude.However,as the temperature decreases further below-140℃,the carrier freeze-out brings about an inflection point,which means the transient amplitude will decrease at cryogenic temperatures.To better understand this result,we analytically calculate the ionization rates of various dopants at different temperatures based on Altermatt's new incomplete ionization model.The parasitic resistivities with temperature on the charge-collection pathway are extracted by a two-dimensional(2D)TCAD process simulation.In addition,we investigate the impact of temperature on the novel electron-injection process from emitter to base under different bias conditions.The increase of the emitter-base junction's barrier height at low temperatures could suppress this electron-injection phenomenon.We have also optimized the built-in voltage equations of a high current compact model(HICUM)by introducing the impact of incomplete ionization.The present results and methods could provide a new reference for effective evaluation of single-event effects in bipolar transistors and circuits at cryogenic temperatures,and could provide a new evidence of the potential of SiGe technology in applications in extreme cryogenic environments.展开更多
The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive positi...The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.展开更多
An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivi...An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.展开更多
The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV C1, 20-MeV Br, and 10-MeV Br ion irradiation, respectively....The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV C1, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in Ic was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.展开更多
Silicon germanium (SiGe) heterojunction bipolar transistor (HBT) on thin silicon-on-insulator (SOI) has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SO...Silicon germanium (SiGe) heterojunction bipolar transistor (HBT) on thin silicon-on-insulator (SOI) has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion, which is different from that of a bulk counterpart. A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation. The Early voltage shows a kink with the increase of the reverse base-collector bias. Large differences are observed between SOI devices and their bulk counterparts. The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design, the simulation and the fabrication of high performance SOI SiCe devices and circuits.展开更多
The base-collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytic...The base-collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytical depletion capacitance model of this structure for the first time. A large discrepancy is predicted when the present model is compared with the conventional depletion model, and it is shown that the capacitance decreases with the increase of the reverse collector- base bias-and shows a kink as the reverse collector-base bias reaches the effective vertical punch-through voltage while the voltage differs with the collector doping concentrations, which is consistent with measurement results. The model can be employed for a fast evaluation of the depletion capacitance of an SOI SiGe HBT and has useful applications on the design and simulation of high performance SiGe circuits and devices.展开更多
An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor (HBT) on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being cons...An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor (HBT) on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.展开更多
Silicon-germanium (SiGe) hereto-junction bipolar transistor current transients induced by pulse laser and heavy iron are measured using a real-time digital oscilloscope. These transients induced by pulse laser and h...Silicon-germanium (SiGe) hereto-junction bipolar transistor current transients induced by pulse laser and heavy iron are measured using a real-time digital oscilloscope. These transients induced by pulse laser and heavy iron exhibit the same waveform and charge collection time except for the amplitude of peak current. Different laser energies and voltage biases under heavy ion irradiation also have impact on current transient, whereas the waveform remains unchanged. The position-correlated current transients suggest that the nature of the current transient is controlled by the behavior of the C/S junction.展开更多
In this paper, we describe the saturation effect of a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) fabricated on a thin silicon-on-insulator (SOI) with a step-by-step derivation of the model ...In this paper, we describe the saturation effect of a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) fabricated on a thin silicon-on-insulator (SOI) with a step-by-step derivation of the model formulation. The collector injection width, the internal base-collector bias, and the hole density at the base-collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.展开更多
The effects of buried oxide(BOX)layer on the capacitance of SiGe heterojunction photo-transistor(HPT),including the collector-substrate capacitance,the base-collector capacitance,and the base-emitter capacitance,are s...The effects of buried oxide(BOX)layer on the capacitance of SiGe heterojunction photo-transistor(HPT),including the collector-substrate capacitance,the base-collector capacitance,and the base-emitter capacitance,are studied by using a silicon-on-insulator(SOI)substrate as compared with the devices on native Si substrates.By introducing the BOX layer into Si-based SiGe HPT,the maximum photo-characteristic frequency ft,opt of SOI-based SiGe HPT reaches up to 24.51 GHz,which is 1.5 times higher than the value obtained from Si-based SiGe HPT.In addition,the maximum optical cut-off frequency fβ,opt,namely its 3-dB bandwidth,reaches up to 1.13 GHz,improved by 1.18 times.However,with the increase of optical power or collector current,this improvement on the frequency characteristic from BOX layer becomes less dominant as confirmed by reducing the 3-dB bandwidth of SOI-based SiGe HPT which approaches to the 3-dB bandwidth of Si-based SiGe HPT at higher injection conditions.展开更多
This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe...This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 1013 cm-2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.展开更多
In this paper, we propose an analytical avalanche multiplication model for the next generation of SiGe silicon- on-insulator (SOI) heterojunction bipolar transistors (HBTs) and consider their vertical and lateral ...In this paper, we propose an analytical avalanche multiplication model for the next generation of SiGe silicon- on-insulator (SOI) heterojunction bipolar transistors (HBTs) and consider their vertical and lateral impact ionizations for the first time. Supported by experimental data, the analytical model predicts that the avalanche multiplication governed by impact ionization shows kinks and the impact ionization effect is small compared with that of the bulk HBT, resulting in a larger base-collector breakdown voltage. The model presented in the paper is significant and has useful applications in the design and simulation of the next generation of SiCe SOI BiCMOS technology.展开更多
The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play t...The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play the role of an light absorbing layer. This paper reports on Si films heteroepitaxially grown on the Si face of (0001) n-type 6H-SiC substrates and the use of B2H6 as a dopant for p-Si grown at temperatures in a range of 700-950℃. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) tests have demonstrated that the samples prepared at the temperatures ranged from 850℃ to 900℃ are characterized as monocrystalline silicon. The rocking XRD curves show a well symmetry with FWHM of 0.4339° Omega. Twin crystals and stacking faults observed in the epitaxial layers might be responsible for widening of the rocking curves. Dependence of the crystal structure and surface topography on growth temperature is discussed based on the experimental results. The energy band structure and rectifying characteristics of the Si/SiC heterojunctions are also preliminarily tested.展开更多
Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characte...Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.展开更多
A study on the single event transient (SET) induced by a pulsed laser in a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) is presented in this work. The impacts of laser energy and collector lo...A study on the single event transient (SET) induced by a pulsed laser in a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) is presented in this work. The impacts of laser energy and collector load resistance on the SET are investigated in detail. The waveform, amplitude, and width of the SET pulse as well as collected charge are used to characterize the SET response. The experimental results are discussed in detail and it is demonstrated that the laser energy and load resistance significantly affect the SET in the SiGe HBT. Furthermore, the underlying physical mechanisms are analyzed and investigated, and a near-ideal exponential model is proposed for the first time to describe the discharge of laser-induced electrons via collector resistance to collector supply when both base-collector and collector-substrate junctions are reverse biased or weakly forward biased. Besides, it is found that an additional multi-path discharge would play an important role in the SET once the base-collector and collector-substrate junctions get strongly forward biased due to a strong transient step charge by the laser pulse.展开更多
The indium-tin oxide (ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction (HJ) solar cells. To obtain high transmittance and low resistivi...The indium-tin oxide (ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction (HJ) solar cells. To obtain high transmittance and low resistivity ITO films by direct-current (DC) magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4 x 10-4 ~.m and average transmittance of 89% in the wavelength range of 380-780 nm were obtained under the optimized conditions: oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si:H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage (Voc) of 0.626 V, a filling factor (FF) of 0.50, and a short circuit current density (Jsc) of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si:H layer was inserted between the (p) a-Si:H and (n) c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si:H.展开更多
A novel structure of Ag gridlSiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:HlTCO/Ag grid was designed to increase the ef- ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material co...A novel structure of Ag gridlSiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:HlTCO/Ag grid was designed to increase the ef- ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost. The simulation results show that the new structure obtains higher efficiency compared with the typical bifa- cial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current (Jsc), while retaining the advantages of a high open-circuit voltage, low temperature coefficient, and good weak-light performance. Moreover, real cells composed of the novel structure with dimensions of 75 mm×75 mm were fabricated by a special fabrication recipe based on industrial processes. Without parameter optimization, the cell efficiency reached 21.1% with the Jsc of 41.7 mA/cm^2. In addition, the novel structure attained 28.55% potential conversion efficiency under an illumination of AM 1.5 G, 100 mW/cm^2. We conclude that the configuration of the Ag grid/SiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:H/TCO/Ag grid is a promising structure for high efficiency and low cost.展开更多
基金the National Natural Science Foundation of China(Grant Nos.61704127 and 11775167)。
文摘We experimentally demonstrate that the dominant mechanism of single-event transients in silicon-germanium heterojunction bipolar transistors(SiGe HBTs)can change with decreasing temperature from+20℃to-180℃.This is accomplished by using a new well-designed cryogenic experimental system suitable for a pulsed-laser platform.Firstly,when the temperature drops from+20℃to-140℃,the increased carrier mobility drives a slight increase in transient amplitude.However,as the temperature decreases further below-140℃,the carrier freeze-out brings about an inflection point,which means the transient amplitude will decrease at cryogenic temperatures.To better understand this result,we analytically calculate the ionization rates of various dopants at different temperatures based on Altermatt's new incomplete ionization model.The parasitic resistivities with temperature on the charge-collection pathway are extracted by a two-dimensional(2D)TCAD process simulation.In addition,we investigate the impact of temperature on the novel electron-injection process from emitter to base under different bias conditions.The increase of the emitter-base junction's barrier height at low temperatures could suppress this electron-injection phenomenon.We have also optimized the built-in voltage equations of a high current compact model(HICUM)by introducing the impact of incomplete ionization.The present results and methods could provide a new reference for effective evaluation of single-event effects in bipolar transistors and circuits at cryogenic temperatures,and could provide a new evidence of the potential of SiGe technology in applications in extreme cryogenic environments.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.61574171,61704127,11875229,51872251,and 12027813)。
文摘The single event effect(SEE) sensitivity of silicon–germanium heterojunction bipolar transistor(Si Ge HBT) irradiated by 100-Me V proton is investigated. The simulation results indicate that the most sensitive position of the Si Ge HBT device is the emitter center, where the protons pass through the larger collector-substrate(CS) junction. Furthermore, in this work the experimental studies are also carried out by using 100-Me V proton. In order to consider the influence of temperature on SEE, both simulation and experiment are conducted at a temperature of 93 K. At a cryogenic temperature, the carrier mobility increases, which leads to higher transient current peaks, but the duration of the current decreases significantly.Notably, at the same proton flux, there is only one single event transient(SET) that occurs at 93 K. Thus, the radiation hard ability of the device increases at cryogenic temperatures. The simulation results are found to be qualitatively consistent with the experimental results of 100-Me V protons. To further evaluate the tolerance of the device, the influence of proton on Si Ge HBT after gamma-ray(^(60)Coγ) irradiation is investigated. As a result, as the cumulative dose increases, the introduction of traps results in a significant reduction in both the peak value and duration of the transient currents.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12261141662, 12074311, and 12004310)。
文摘An in-depth understanding of the photoconductivity and photocarrier density at the interface is of great significance for improving the performance of optoelectronic devices. However, extraction of the photoconductivity and photocarrier density at the heterojunction interface remains elusive. Herein, we have obtained the photoconductivity and photocarrier density of 173 nm Sb2Se3/Si(type-Ⅰ heterojunction) and 90 nm Sb2Se3/Si(type-Ⅱ heterojunction) utilizing terahertz(THz) time-domain spectroscopy(THz-TDS) and a theoretical Drude model. Since type-Ⅰ heterojunctions accelerate carrier recombination and type-Ⅱ heterojunctions accelerate carrier separation, the photoconductivity and photocarrier density of the type-Ⅱ heterojunction(21.8×10^(4)S·m^(-1),1.5 × 10^(15)cm^(-3)) are higher than those of the type-Ⅰ heterojunction(11.8×10^(4)S·m^(-1),0.8×10^(15)cm^(-3)). These results demonstrate that a type-Ⅱ heterojunction is superior to a type-Ⅰ heterojunction for THz wave modulation. This work highlights THz-TDS as an effective tool for studying photoconductivity and photocarrier density at the heterojunction interface. In turn, the intriguing interfacial photoconductivity effect provides a way to improve the THz wave modulation performance.
基金supported by the National Natural Science Foundation of China(Grant No.60976013)
文摘The degradations in NPN silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) were fully studied in this work, by means of 25-MeV Si, 10-MeV C1, 20-MeV Br, and 10-MeV Br ion irradiation, respectively. Electrical parameters such as the base current (IB), current gain (β), neutral base recombination (NBR), and Early voltage (VA) were investigated and used to evaluate the tolerance to heavy ion irradiation. Experimental results demonstrate that device degradations are indeed radiation-source-dependent, and the larger the ion nuclear energy loss is, the more the displacement damages are, and thereby the more serious the performance degradation is. The maximum degradation was observed in the transistors irradiated by 10-MeV Br. For 20-MeV and 10-MeV Br ion irradiation, an unexpected degradation in Ic was observed and Early voltage decreased with increasing ion fluence, and NBR appeared to slow down at high ion fluence. The degradations in SiGe HBTs were mainly attributed to the displacement damages created by heavy ion irradiation in the transistors. The underlying physical mechanisms are analyzed and investigated in detail.
基金Project supported by the National Ministries and Commissions (Grant Nos. 51308040203 and 6139801)the Fundamental Research Funds for the Central Universities of China (Grant Nos. 72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China (Grant No. 2010JQ8008)
文摘Silicon germanium (SiGe) heterojunction bipolar transistor (HBT) on thin silicon-on-insulator (SOI) has recently been demonstrated and integrated into the latest SOI BiCMOS technology. The Early effect of the SOI SiGe HBT is analysed considering vertical and horizontal collector depletion, which is different from that of a bulk counterpart. A new compact formula of the Early voltage is presented and validated by an ISE TCAD simulation. The Early voltage shows a kink with the increase of the reverse base-collector bias. Large differences are observed between SOI devices and their bulk counterparts. The presented Early effect model can be employed for a fast evaluation of the Early voltage and is useful to the design, the simulation and the fabrication of high performance SOI SiCe devices and circuits.
基金Project supported by the National Ministries and Commissions(Grant Nos.51308040203,72105499,and6139801)
文摘The base-collector depletion capacitance for vertical SiGe npn heterojunction bipolar transistors (HBTs) on silicon on insulator (SOI) is split into vertical and lateral parts. This paper proposes a novel analytical depletion capacitance model of this structure for the first time. A large discrepancy is predicted when the present model is compared with the conventional depletion model, and it is shown that the capacitance decreases with the increase of the reverse collector- base bias-and shows a kink as the reverse collector-base bias reaches the effective vertical punch-through voltage while the voltage differs with the collector doping concentrations, which is consistent with measurement results. The model can be employed for a fast evaluation of the depletion capacitance of an SOI SiGe HBT and has useful applications on the design and simulation of high performance SiGe circuits and devices.
基金Project supported by National Ministries and Commissions(Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities,China(Grant Nos.72105499 and 72104089)the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2010JQ8008)
文摘An analytical expression for the co/lector resistance of a novel vertical SiGe heterojunction bipolar transistor (HBT) on thin film silicon-on-insulator (SOI) is obtained with the substrate bias effects being considered. The resistance is found to decrease slowly and then quickly and to have kinks with the increase of the substrate-collector bias, which is quite different from that of a conventional bulk HBT. The model is consistent with the simulation result and the reported data and is useful to the frequency characteristic design of 0.13 μtm millimeter-wave SiGe SOI BiCMOS devices.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61274106 and 61574171
文摘Silicon-germanium (SiGe) hereto-junction bipolar transistor current transients induced by pulse laser and heavy iron are measured using a real-time digital oscilloscope. These transients induced by pulse laser and heavy iron exhibit the same waveform and charge collection time except for the amplitude of peak current. Different laser energies and voltage biases under heavy ion irradiation also have impact on current transient, whereas the waveform remains unchanged. The position-correlated current transients suggest that the nature of the current transient is controlled by the behavior of the C/S junction.
基金Project supported by the National Ministries and Commissions,China (Grant Nos.51308040203 and 6139801)the Fundamental Research Funds for the Central Universities,China (Grant Nos.72105499 and 72104089)the Basic Natural Science Research Program in Shaanxi Province,China (Grant No.2010JQ8008)
文摘In this paper, we describe the saturation effect of a silicon germanium (SiGe) heterojunction bipolar transistor (HBT) fabricated on a thin silicon-on-insulator (SOI) with a step-by-step derivation of the model formulation. The collector injection width, the internal base-collector bias, and the hole density at the base-collector junction interface are analysed by considering the unique features of the internal and the external parts of the collector, as they are different from those of a bulk counterpart.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61604106,61774012,and 61901010)the Beijing Future Chip Technology High Precision Innovation Center Research Fund,China(Grant No.KYJJ2016008)+1 种基金the Beijing Municipal Natural Science Foundation,China(Grant No.4192014)the Municipal Natural Science Foundation of Shangdong Province,China(Grant No.ZR2014FL025).
文摘The effects of buried oxide(BOX)layer on the capacitance of SiGe heterojunction photo-transistor(HPT),including the collector-substrate capacitance,the base-collector capacitance,and the base-emitter capacitance,are studied by using a silicon-on-insulator(SOI)substrate as compared with the devices on native Si substrates.By introducing the BOX layer into Si-based SiGe HPT,the maximum photo-characteristic frequency ft,opt of SOI-based SiGe HPT reaches up to 24.51 GHz,which is 1.5 times higher than the value obtained from Si-based SiGe HPT.In addition,the maximum optical cut-off frequency fβ,opt,namely its 3-dB bandwidth,reaches up to 1.13 GHz,improved by 1.18 times.However,with the increase of optical power or collector current,this improvement on the frequency characteristic from BOX layer becomes less dominant as confirmed by reducing the 3-dB bandwidth of SOI-based SiGe HPT which approaches to the 3-dB bandwidth of Si-based SiGe HPT at higher injection conditions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775167,61574171,11575138,and 11835006)
文摘This paper presents an investigation into the impact of proton-induced alteration of carrier lifetime on the singleevent transient(SET) caused by heavy ions in silicon–germanium heterojunction bipolar transistor(SiGe HBT).The ioninduced current transients and integrated charge collections under different proton fluences are obtained based on technology computer-aided design(TCAD) simulation.The results indicate that the impact of carrier lifetime alteration is determined by the dominating charge collection mechanism at the ion incident position and only the long-time diffusion process is affected.With a proton fluence of 5 × 1013 cm-2, almost no change is found in the transient feature, and the charge collection of events happened in the region enclosed by deep trench isolation(DTI), where prompt funneling collection is the dominating mechanism.Meanwhile, for the events happening outside DTI where diffusion dominates the collection process, the peak value and the duration of the ion-induced current transient both decrease with increasing proton fluence, leading to a great decrease in charge collection.
基金supported by the Science Foundation of National Ministries and Commissions (Grant Nos. 51308040203 and 6139801)the Fundamental Research Funds for the Central Universities of China (Grant Nos. 72105499 and 72104089)the Natural Science Basic Research Program in Shaanxi Province of China (Grant No. 2010JQ8008)
文摘In this paper, we propose an analytical avalanche multiplication model for the next generation of SiGe silicon- on-insulator (SOI) heterojunction bipolar transistors (HBTs) and consider their vertical and lateral impact ionizations for the first time. Supported by experimental data, the analytical model predicts that the avalanche multiplication governed by impact ionization shows kinks and the impact ionization effect is small compared with that of the bulk HBT, resulting in a larger base-collector breakdown voltage. The model presented in the paper is significant and has useful applications in the design and simulation of the next generation of SiCe SOI BiCMOS technology.
基金Project supported by the National Natural Science Foundation of China (Grant No 60576044)
文摘The Si on SiC heterojunction is still poorly understood, although it has a number of potential applications in electronic and optoelectronic devices, for example, light-activated SiC power switches where Si may play the role of an light absorbing layer. This paper reports on Si films heteroepitaxially grown on the Si face of (0001) n-type 6H-SiC substrates and the use of B2H6 as a dopant for p-Si grown at temperatures in a range of 700-950℃. X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM) tests have demonstrated that the samples prepared at the temperatures ranged from 850℃ to 900℃ are characterized as monocrystalline silicon. The rocking XRD curves show a well symmetry with FWHM of 0.4339° Omega. Twin crystals and stacking faults observed in the epitaxial layers might be responsible for widening of the rocking curves. Dependence of the crystal structure and surface topography on growth temperature is discussed based on the experimental results. The energy band structure and rectifying characteristics of the Si/SiC heterojunctions are also preliminarily tested.
基金supported in part by the Strategic Priority Research Program of the Chinese Academy of Sciences (Project ID.XDA0330300)in part by Innovation Program for Quantum Science and Technology (Project ID.2021ZD0302301)in part by the Youth Innovation Promotion Association of CAS (Project ID.2020037)。
文摘Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60976013)
文摘A study on the single event transient (SET) induced by a pulsed laser in a silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) is presented in this work. The impacts of laser energy and collector load resistance on the SET are investigated in detail. The waveform, amplitude, and width of the SET pulse as well as collected charge are used to characterize the SET response. The experimental results are discussed in detail and it is demonstrated that the laser energy and load resistance significantly affect the SET in the SiGe HBT. Furthermore, the underlying physical mechanisms are analyzed and investigated, and a near-ideal exponential model is proposed for the first time to describe the discharge of laser-induced electrons via collector resistance to collector supply when both base-collector and collector-substrate junctions are reverse biased or weakly forward biased. Besides, it is found that an additional multi-path discharge would play an important role in the SET once the base-collector and collector-substrate junctions get strongly forward biased due to a strong transient step charge by the laser pulse.
基金supported by the National High Technology Research and Development Program of China(Grant No.2011AA050501)
文摘The indium-tin oxide (ITO) film as the antireflection layer and front electrodes is of key importance to obtaining high efficiency Si heterojunction (HJ) solar cells. To obtain high transmittance and low resistivity ITO films by direct-current (DC) magnetron sputtering, we studied the impacts of the ITO film deposition conditions, such as the oxygen flow rate, pressure, and sputter power, on the electrical and optical properties of the ITO films. ITO films of resistivity of 4 x 10-4 ~.m and average transmittance of 89% in the wavelength range of 380-780 nm were obtained under the optimized conditions: oxygen flow rate of 0.1 sccm, pressure of 0.8 Pa, and sputtering power of 110 W. These ITO films were used to fabricate the single-side HJ solar cell without an intrinsic a-Si:H layer. However, the best HJ solar cell was fabricated with a lower sputtering power of 95 W, which had an efficiency of 11.47%, an open circuit voltage (Voc) of 0.626 V, a filling factor (FF) of 0.50, and a short circuit current density (Jsc) of 36.4 mA/cm2. The decrease in the performance of the solar cell fabricated with high sputtering power of 110 W is attributed to the ion bombardment to the emitter. The Voc was improved to 0.673 V when a 5 nm thick intrinsic a-Si:H layer was inserted between the (p) a-Si:H and (n) c-Si layer. The higher Voc of 0.673 V for the single-side HJ solar cell implies the excellent c-Si surface passivation by a-Si:H.
基金Project supported by the Jiangxi Provincial Key Research and Development Foundation,China(Grant No.2016BBH80043)the Open Fund of Jiangsu Key Laboratory of Materials and Technology for Energy Conversion,China(Grant No.NJ20160032)the National Natural Science Foundation of China(Grant Nos.61741404,61464007,and 51561022)
文摘A novel structure of Ag gridlSiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:HlTCO/Ag grid was designed to increase the ef- ficiency of bifacial amorphous/crystalline silicon-based solar cells and reduce the rear material consumption and production cost. The simulation results show that the new structure obtains higher efficiency compared with the typical bifa- cial amorphous/crystalline silicon-based solar cell because of an increase in the short-circuit current (Jsc), while retaining the advantages of a high open-circuit voltage, low temperature coefficient, and good weak-light performance. Moreover, real cells composed of the novel structure with dimensions of 75 mm×75 mm were fabricated by a special fabrication recipe based on industrial processes. Without parameter optimization, the cell efficiency reached 21.1% with the Jsc of 41.7 mA/cm^2. In addition, the novel structure attained 28.55% potential conversion efficiency under an illumination of AM 1.5 G, 100 mW/cm^2. We conclude that the configuration of the Ag grid/SiNx/n+-c-Si/n-c-Si/i-a-Si:H/p+-a-Si:H/TCO/Ag grid is a promising structure for high efficiency and low cost.