In this paper,drain current transient characteristics ofβ-Ga2O3 high electron mobility transistor(HEMT)are studied to access current collapse and recovery time due to dynamic population and de-population of deep leve...In this paper,drain current transient characteristics ofβ-Ga2O3 high electron mobility transistor(HEMT)are studied to access current collapse and recovery time due to dynamic population and de-population of deep level traps and interface traps.An approximately 10 min,and 1 h of recovery time to steady-state drain current value is measured under 1 ms of stress on the gate and drain electrodes due to iron(Fe)–dopedβ-Ga2O3 substrate and germanium(Ge)–dopedβ-Ga2O3 epitaxial layer respectively.On-state current lag is more severe due to widely reported defect trap EC–0.82 e V over EC–0.78 e V,-0.75 e V present in Iron(Fe)-dopedβ-Ga2O3 bulk crystals.A negligible amount of current degradation is observed in the latter case due to the trap level at EC–0.98 e V.It is found that occupancy of ionized trap density varied mostly under the gate and gate–source area.This investigation of reversible current collapse phenomenon and assessment of recovery time inβ-Ga2O3 HEMT is carried out through 2 D device simulations using appropriate velocity and charge transport models.This work can further help in the proper characterization ofβ-Ga2O3 devices to understand temporary and permanent device degradation.展开更多
SiNx is commonly used as a passivation material for AlGaN/GaN high electron mobility transistors (HEMTs). In this paper, the effects of SiNx passivation film on both two-dimensional electron gas characteristics and ...SiNx is commonly used as a passivation material for AlGaN/GaN high electron mobility transistors (HEMTs). In this paper, the effects of SiNx passivation film on both two-dimensional electron gas characteristics and current collapse of A1GaN/GaN HEMTs are investigated. The SiNx films are deposited by high- and low-frequency plasma-enhanced chemical vapour deposition, and they display different strains on the AlGaN/GaN heterostructure, which can explain the experiment results.展开更多
In this paper, two-dimensional (2D) transient simulations of an A1GaN/GaN high-electron-mobility transistor (HEMT) are carded out and analyzed to investigate the current collapse due to trapping effects. The coupl...In this paper, two-dimensional (2D) transient simulations of an A1GaN/GaN high-electron-mobility transistor (HEMT) are carded out and analyzed to investigate the current collapse due to trapping effects. The coupling effect of the trapping and thermal effects are taken into account in our simulation. The turn-on pulse gate-lag transient responses with different quiescent biases are obtained, and the pulsed current-voltage (l-V) curves are extracted from the transients. The experimental results of both gate-lag transient current and pulsed I-V curves are reproduced by the simulation, and the current collapse due to the trapping effect is explained from the view of physics based on the simulation results. In addition, the results show that bulk acceptor traps can influence the gate-lag transient characteristics of A1GaN/GaN HEMTs besides surface traps and that the thermal effect can accelerate the emission of captured electrons for traps. Pulse transient simulation is meaningful in analyzing the mechanism of dynamic current collapse, and the work in this paper will benefit the reliability study and model development of GaN-based devices.展开更多
This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation ca...This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiNx passivation located in the gate-drain region. As the thickness of SiNx passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.展开更多
Current collapses were studied, which were observed in A1GaN/GaN high electron mobility transistors (HEMTs) with and without InGaN back barrier (BB) as a result of short-term bias stress. More serious drain curren...Current collapses were studied, which were observed in A1GaN/GaN high electron mobility transistors (HEMTs) with and without InGaN back barrier (BB) as a result of short-term bias stress. More serious drain current collapses were observed in InGaN BB A1GaN/GaN HEMTs compared with the traditional HEMTs. The results indicate that the defects and surface states induced by the InGaN BB layer may enhance the current collapse. The surface states may be the primary mechanism of the origination of current collapse in A1GaN/GaN HEMTs for short-term direct current stress.展开更多
The breakdown and the current collapse characteristics of high electron mobility transistors (HEMTs) with a low power F-plasma treatment process are investigated. With the increase of F-plasma treatment time, the sa...The breakdown and the current collapse characteristics of high electron mobility transistors (HEMTs) with a low power F-plasma treatment process are investigated. With the increase of F-plasma treatment time, the saturation current decreases, and the threshold voltage shifts to the positive slightly. Through analysis of the Schottky characteristics of the devices with different F-plasma treatment times, it was found that an optimal F-plasma treatment time of 120 s obviously reduced the gate reverse leakage current and improved the breakdown voltage of the devices, but longer F-plasma treatment time than 120 s did not reduce gate reverse leakage current due to plasma damage. The current collapse characteristics of the HEMTs with F-plasma treatment were evaluated by dual pulse measurement at different bias voltages and no obvious deterioration of current collapse were found after low power F-plasma treatment.展开更多
Direct current (DC) and pulsed measurements are performed to determine the degradation mechanisms of A1GaN/GaN high electron mobility transistors (HEMTs) under high temperature. The degradation of the DC character...Direct current (DC) and pulsed measurements are performed to determine the degradation mechanisms of A1GaN/GaN high electron mobility transistors (HEMTs) under high temperature. The degradation of the DC characteristics is mainly attributed to the reduction in the density and the mobility of the two-dimensional electron gas (2DEG). The pulsed measurements indicate that the trap assisted tunneling is the dominant gate leakage mechanism in the temperature range of interest. The traps in the barrier layer become active as the temperature increases, which is conducive to the electron tunneling between the gate and the channel. The enhancement of the tunneling results in the weakening of the current collapse effects, as the electrons trapped by the barrier traps can escape more easily at the higher temperature.展开更多
We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilay...We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilayer SiN with 20-nm Si-rich SiN and 100-nm Si_(3)N_(4) was deposited by plasma-enhanced chemical vapor deposition(PECVD)after removing 20-nm SiO_(2)pre-deposition layer.Compared to traditional Si_(3)N_(4) passivation for thin-barrier AlGaN/GaN HEMTs,Si-rich SiN bilayer passivation can suppress the current collapse ratio from 18.54%to 8.40%.However,Si-rich bilayer passivation leads to a severer surface leakage current,so that it has a low breakdown voltage.The 20-nm SiO_(2)pre-deposition layer can protect the surface of HEMTs in fabrication process and decrease Ga–O bonds,resulting in a lower surface leakage current.In contrast to passivating Si-rich SiN directly,devices with the novel Si-rich SiN bilayer passivation increase the breakdown voltage from 29 V to 85 V.Radio frequency(RF)small-signal characteristics show that HEMTs with the novel bilayer SiN passivation leads to f_(T)/f_(max) of 68 GHz/102 GHz.At 30 GHz and V_(DS)=20 V,devices achieve a maximum P_(out) of 5.2 W/mm and a peak power-added efficiency(PAE)of 42.2%.These results indicate that HEMTs with the novel bilayer SiN passivation can have potential applications in the millimeter-wave range.展开更多
This paper studies the drain current collapse of A1GaN/GaN metal insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbA10 dielectric by applying dual-pulsed stress to the gate and drain of t...This paper studies the drain current collapse of A1GaN/GaN metal insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbA10 dielectric by applying dual-pulsed stress to the gate and drain of the device. For NbA10 MIS-HEMT, smaller current collapse is found thorough study of the gate-drain conductance dispersion especially when the gate static voltage is -8 V. Through a it is found that the growth of NbA10 can reduce the trap density of the AlGaN surface. Therefore, fewer traps can be filled by gate electrons, and hence the depletion effect in the channel is suppressed effectively. It is proved that the NbAIO gate dielectric can not only decrease gate leakage current but also passivate the A1GaN surface effectively, and weaken the current collapse effect accordingly.展开更多
Trapping of hot electron behavior by trap centres located in buffer layer of a wurtzite phase GaN MESFET has been simulated using an ensemble Monte Carlo simulation. The simulated results show the trap centres are res...Trapping of hot electron behavior by trap centres located in buffer layer of a wurtzite phase GaN MESFET has been simulated using an ensemble Monte Carlo simulation. The simulated results show the trap centres are responsible for current collapse in GaN MESFET at low temperatures. These electrical traps degrade the performance of the device at low temperature. On the opposite, a light-induced increase in the trap-limited drain current results from the photoionization of trapped carriers and their return to the channel under the influence of the built in electric field associated with the trapped charge distribution. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted drain current and other electrical characteristics for the simulated device including trapping centre effects show close agreement with the available experimantal data.展开更多
The relationship between A1GaN/GaN HEMT gate field plate (FP) and surface-state-related gate lag phenomena is investigated by two-dimensional numerical transient simulations to study the mechanism of the influence o...The relationship between A1GaN/GaN HEMT gate field plate (FP) and surface-state-related gate lag phenomena is investigated by two-dimensional numerical transient simulations to study the mechanism of the influence of FPs on current collapse. The simulations reveal that adding a field plate has a noticeable impact on the extent of current collapse while it has no influence on lapsed time. The FP is found to suppress current collapse through reducing the ionization probability of surface states by enhancing free hole accumulation next to the AIGaN surface between gate and drain.展开更多
基金an outcome of the collaborative R&D work undertaken in the project under the Visvesvaraya PhD Scheme of Ministry of Electronics&Information Technology,Govt.of India,being implemented by Digital India Corporation。
文摘In this paper,drain current transient characteristics ofβ-Ga2O3 high electron mobility transistor(HEMT)are studied to access current collapse and recovery time due to dynamic population and de-population of deep level traps and interface traps.An approximately 10 min,and 1 h of recovery time to steady-state drain current value is measured under 1 ms of stress on the gate and drain electrodes due to iron(Fe)–dopedβ-Ga2O3 substrate and germanium(Ge)–dopedβ-Ga2O3 epitaxial layer respectively.On-state current lag is more severe due to widely reported defect trap EC–0.82 e V over EC–0.78 e V,-0.75 e V present in Iron(Fe)-dopedβ-Ga2O3 bulk crystals.A negligible amount of current degradation is observed in the latter case due to the trap level at EC–0.98 e V.It is found that occupancy of ionized trap density varied mostly under the gate and gate–source area.This investigation of reversible current collapse phenomenon and assessment of recovery time inβ-Ga2O3 HEMT is carried out through 2 D device simulations using appropriate velocity and charge transport models.This work can further help in the proper characterization ofβ-Ga2O3 devices to understand temporary and permanent device degradation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60536020 and 60723002)the National Basic Research Program of China (Grant Nos. 2006CB302800 and 2006CB921106)+1 种基金the National High Technology Research and Development Program for Advanced Materials of China (Grant No. 2006AA03A105)the Major Project of Beijing Municipal Science and Technology Commission, China (Grant No. D0404003040321)
文摘SiNx is commonly used as a passivation material for AlGaN/GaN high electron mobility transistors (HEMTs). In this paper, the effects of SiNx passivation film on both two-dimensional electron gas characteristics and current collapse of A1GaN/GaN HEMTs are investigated. The SiNx films are deposited by high- and low-frequency plasma-enhanced chemical vapour deposition, and they display different strains on the AlGaN/GaN heterostructure, which can explain the experiment results.
基金Project supported by the National Natural Science Foundation of China(Grant No.61306113)
文摘In this paper, two-dimensional (2D) transient simulations of an A1GaN/GaN high-electron-mobility transistor (HEMT) are carded out and analyzed to investigate the current collapse due to trapping effects. The coupling effect of the trapping and thermal effects are taken into account in our simulation. The turn-on pulse gate-lag transient responses with different quiescent biases are obtained, and the pulsed current-voltage (l-V) curves are extracted from the transients. The experimental results of both gate-lag transient current and pulsed I-V curves are reproduced by the simulation, and the current collapse due to the trapping effect is explained from the view of physics based on the simulation results. In addition, the results show that bulk acceptor traps can influence the gate-lag transient characteristics of A1GaN/GaN HEMTs besides surface traps and that the thermal effect can accelerate the emission of captured electrons for traps. Pulse transient simulation is meaningful in analyzing the mechanism of dynamic current collapse, and the work in this paper will benefit the reliability study and model development of GaN-based devices.
基金Project supported by the State Key Program of National Natural Science Foundation of China (Grant No. 60736033)
文摘This paper investigates the impact of electrical degradation and current collapse on different thickness SiNx passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiNx passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiNx passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiNx passivation located in the gate-drain region. As the thickness of SiNx passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse.
基金supported by the Knowledge Innovation Engineering of the Chinese Academy of Sciences(No.YYY-0701-02)the National Natural Science Foundation of China(Nos.60890193,61106014)+1 种基金the State Key Development Program for Basic Research of China(No.2010CB327503)the National Science and Technology Major Project
文摘Current collapses were studied, which were observed in A1GaN/GaN high electron mobility transistors (HEMTs) with and without InGaN back barrier (BB) as a result of short-term bias stress. More serious drain current collapses were observed in InGaN BB A1GaN/GaN HEMTs compared with the traditional HEMTs. The results indicate that the defects and surface states induced by the InGaN BB layer may enhance the current collapse. The surface states may be the primary mechanism of the origination of current collapse in A1GaN/GaN HEMTs for short-term direct current stress.
基金supported by the National Natural Science Foundation of China(No.61106106)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(No.ZHD201206)the Fundamental Research Funds for the Central Universities(Nos.K5051325004,K5051325002)
文摘The breakdown and the current collapse characteristics of high electron mobility transistors (HEMTs) with a low power F-plasma treatment process are investigated. With the increase of F-plasma treatment time, the saturation current decreases, and the threshold voltage shifts to the positive slightly. Through analysis of the Schottky characteristics of the devices with different F-plasma treatment times, it was found that an optimal F-plasma treatment time of 120 s obviously reduced the gate reverse leakage current and improved the breakdown voltage of the devices, but longer F-plasma treatment time than 120 s did not reduce gate reverse leakage current due to plasma damage. The current collapse characteristics of the HEMTs with F-plasma treatment were evaluated by dual pulse measurement at different bias voltages and no obvious deterioration of current collapse were found after low power F-plasma treatment.
基金supported by the National Natural Science Foundation of China(Grant No.60736033)
文摘Direct current (DC) and pulsed measurements are performed to determine the degradation mechanisms of A1GaN/GaN high electron mobility transistors (HEMTs) under high temperature. The degradation of the DC characteristics is mainly attributed to the reduction in the density and the mobility of the two-dimensional electron gas (2DEG). The pulsed measurements indicate that the trap assisted tunneling is the dominant gate leakage mechanism in the temperature range of interest. The traps in the barrier layer become active as the temperature increases, which is conducive to the electron tunneling between the gate and the channel. The enhancement of the tunneling results in the weakening of the current collapse effects, as the electrons trapped by the barrier traps can escape more easily at the higher temperature.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFB1804902)the National Natural Science Foundation of China(Grant Nos.61904135,62090014,and 11690042)+4 种基金the Fundamental Research Funds for the Central Universities,the Innovation Fund of Xidian University(Grant No.YJS2213)the China Postdoctoral Science Foundation(Grant Nos.2018M640957 and BX20200262)the Key Research and Development Program of Guangzhou(Grant No.202103020002)Wuhu and Xidian University Special Fund for Industry–University-Research Cooperation(Grant No.XWYCXY-012021014HT)the Fundamental Research Funds for the Central Universities,China(Grant No.XJS221110)。
文摘We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilayer SiN with 20-nm Si-rich SiN and 100-nm Si_(3)N_(4) was deposited by plasma-enhanced chemical vapor deposition(PECVD)after removing 20-nm SiO_(2)pre-deposition layer.Compared to traditional Si_(3)N_(4) passivation for thin-barrier AlGaN/GaN HEMTs,Si-rich SiN bilayer passivation can suppress the current collapse ratio from 18.54%to 8.40%.However,Si-rich bilayer passivation leads to a severer surface leakage current,so that it has a low breakdown voltage.The 20-nm SiO_(2)pre-deposition layer can protect the surface of HEMTs in fabrication process and decrease Ga–O bonds,resulting in a lower surface leakage current.In contrast to passivating Si-rich SiN directly,devices with the novel Si-rich SiN bilayer passivation increase the breakdown voltage from 29 V to 85 V.Radio frequency(RF)small-signal characteristics show that HEMTs with the novel bilayer SiN passivation leads to f_(T)/f_(max) of 68 GHz/102 GHz.At 30 GHz and V_(DS)=20 V,devices achieve a maximum P_(out) of 5.2 W/mm and a peak power-added efficiency(PAE)of 42.2%.These results indicate that HEMTs with the novel bilayer SiN passivation can have potential applications in the millimeter-wave range.
基金Project supported by the State Key Program and Major Program of the National Natural Science Foundation of China (Grant Nos. 60736033 and 60890191)the Fundamental Research Funds for the Central Universities (Grant Nos. JY10000925002 and JY10000904009)
文摘This paper studies the drain current collapse of A1GaN/GaN metal insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbA10 dielectric by applying dual-pulsed stress to the gate and drain of the device. For NbA10 MIS-HEMT, smaller current collapse is found thorough study of the gate-drain conductance dispersion especially when the gate static voltage is -8 V. Through a it is found that the growth of NbA10 can reduce the trap density of the AlGaN surface. Therefore, fewer traps can be filled by gate electrons, and hence the depletion effect in the channel is suppressed effectively. It is proved that the NbAIO gate dielectric can not only decrease gate leakage current but also passivate the A1GaN surface effectively, and weaken the current collapse effect accordingly.
文摘Trapping of hot electron behavior by trap centres located in buffer layer of a wurtzite phase GaN MESFET has been simulated using an ensemble Monte Carlo simulation. The simulated results show the trap centres are responsible for current collapse in GaN MESFET at low temperatures. These electrical traps degrade the performance of the device at low temperature. On the opposite, a light-induced increase in the trap-limited drain current results from the photoionization of trapped carriers and their return to the channel under the influence of the built in electric field associated with the trapped charge distribution. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible, and the predicted drain current and other electrical characteristics for the simulated device including trapping centre effects show close agreement with the available experimantal data.
文摘The relationship between A1GaN/GaN HEMT gate field plate (FP) and surface-state-related gate lag phenomena is investigated by two-dimensional numerical transient simulations to study the mechanism of the influence of FPs on current collapse. The simulations reveal that adding a field plate has a noticeable impact on the extent of current collapse while it has no influence on lapsed time. The FP is found to suppress current collapse through reducing the ionization probability of surface states by enhancing free hole accumulation next to the AIGaN surface between gate and drain.