Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)...Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)Te_(3)focus on band and microstructure engineering.However,a clear understanding of the modulation of band structure and scattering through such engineering remains still challenging,because the minority carriers compensate partially the overall transport properties for the narrow-gap Bi_(2)Te_(3)at room temperature(known as the bipolar effect).The purpose of this work is to model the transport properties near and far away from the bipolar effect region for Bi_(2)Te_(3)-based thermoelectric material by a two-band model taking contributions of both majority and minority carriers into account.This is endowed by shifting the Fermi level from the conduction band to the valence band during the modeling.A large amount of data of Bi_(2)Te_(3)-based materials is collected from various studies for the comparison between experimental and predicted properties.The fundamental parameters,such as the density of states effective masses and deformation potential coefficients,of Bi_(2)Te_(3)-based materials are quantified.The analysis can help find out the impact factors(e.g.the mobility ratio between conduction and valence bands)for the improvement of thermoelectric properties for Bi_(2)Te_(3)-based alloys.This work provides a convenient tool for analyzing and predicting the transport performance even in the presence of bipolar effect,which can facilitate the development of the narrow-gap thermoelectric semiconductors.展开更多
Good performance SiGe power amplifiers applicable to wireless communications are demonstrated.The output power can reach more than 30dBm in class B mode.And in class AB mode,the output power at 1dB compression point (...Good performance SiGe power amplifiers applicable to wireless communications are demonstrated.The output power can reach more than 30dBm in class B mode.And in class AB mode,the output power at 1dB compression point ( P 1dB ) is 24dBm,the output third order intercept (TOI) power is 39dBm under V cc of 4V.The highest power added efficiency (PAE) and PAE at 1dB compression point are 34% and 25%,respectively.The adjacent channel power rejection for CDMA signal is more than 42dBc,which complies with IS95 specification.展开更多
A monolithic microwave integrated circuit （MMIC） power amplifier （PA） is proposed. It adopts a new on-chip bias circuit, which not only avoids the instability of the direct current bias caused by the change in the...A monolithic microwave integrated circuit （MMIC） power amplifier （PA） is proposed. It adopts a new on-chip bias circuit, which not only avoids the instability of the direct current bias caused by the change in the power supply and temperature, but also compensates deviations caused by the increase in input power. The bias circuit is a current-mirror configuration, and the feedback circuit helps to maintain bias voltage at a constant level. The gain of the feedback circuit is improved by the addition of a non-inverting amplifier within the feedback circuit. A shunt capacitor at the base node of the active bias transistor enhances the linearity of the PA. The chip is fabricated in an InGaP/GaAs heterojunction bipolar transistor （HBT） process. Measured results exhibit a 26. 6-dBm output compression point, 33.6% power-added efficiency （PAE） and - 40.2 dBc adjacent channel power ratio （ACPR） for wide-band code division multiple access （W-CDMA） applications.展开更多
An emitter self-aligned InP-based single heterojunction bipolar transistor with a cutoff frequency （fT） of 162GHz is reported. The emitter size is 0.8μm × 12μm, the maximum DC gain is 120, the offset voltage ...An emitter self-aligned InP-based single heterojunction bipolar transistor with a cutoff frequency （fT） of 162GHz is reported. The emitter size is 0.8μm × 12μm, the maximum DC gain is 120, the offset voltage is 0.10V,and the typical breakdown voltage at Ic = 0. 1μA is 3.8V. This device is suitable for high-speed low-power applications,such as OEIC receivers and analog-to-digital converters.展开更多
An InP-based single-heterojunction bipolar transistor （SHBT） with base μ-bndge and emitter air-bridge is reported. Because those bridges reduce parasitic capacitance greatly, the cutoff frequency fT of the 2μm ...An InP-based single-heterojunction bipolar transistor （SHBT） with base μ-bndge and emitter air-bridge is reported. Because those bridges reduce parasitic capacitance greatly, the cutoff frequency fT of the 2μm ×12.5μm InP SHBT without de-embedding reaches 178GHz. It is critical in high-speed low power applications,such as OEIC receivers and analog-to-digital converters.展开更多
Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and ...Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and low knee voltage (<0 5V).Over 14V of the collector base breakdown voltage BV CBO and over 9V of the collector emitter breakdown voltage BV CEO are obtained.For a self aligned InGaP/GaAs HBT with 2μm×10μm emitter area,the f T is extrapolated to 92GHz and f max is extrapolated to 105GHz.These great values are obtained due to the hexagonal emitter and laterally etched undercut (LEU) of collector,indicating the great potential of InGaP/GaAs HBTs for high speed digital circuit and microwave power applications.展开更多
The alloy temperature dependence of Voffset and Rcontact is studied, and an optimal alloy temperature range for the best trade-off between Voffset and Rcontact, is given for thin base HBTs. In addition,the reason for ...The alloy temperature dependence of Voffset and Rcontact is studied, and an optimal alloy temperature range for the best trade-off between Voffset and Rcontact, is given for thin base HBTs. In addition,the reason for the high Voffset at high alloy temperature is interpreted using Schottky clamped theory. The lower Voffset of our U-shaped emitter HBT than that of traditional strip emitter HBTs is explained.展开更多
This paper describes the bipolar field-effect transistor （BiFET） and its theory. Analytical solution is ob- tained from partitioning the two-dimensional transistor into two one-dimensional transistors. The analysis ...This paper describes the bipolar field-effect transistor （BiFET） and its theory. Analytical solution is ob- tained from partitioning the two-dimensional transistor into two one-dimensional transistors. The analysis employs the parametric surface-electric-potential and the electrochemical （quasi-Fermi） potential-gradient driving force to compute the current. Output and transfer D. C. current and conductance versus voltage are presented over practi- cal ranges of terminal D. C. voltages and device parameters. Electron and hole surface channel currents are pres- ent simultaneously, a new feature which could provide circuit functions in one physical transistor such as the CMOS inverter and SRAM memory.展开更多
This paper describes the drift-diffusion theory of the bipolar field-effect transistor （BiFET） with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin-pure-base. Analytical solution is obt...This paper describes the drift-diffusion theory of the bipolar field-effect transistor （BiFET） with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin-pure-base. Analytical solution is obtained by partitioning the two-dimensional transistor into two one-dimensional problems coupled by the parametric sur- face-electric-potential. Total and component output and transfer currents and conductances versus D. C. voltages from the drift-diffusion theory, and their deviations from the electrochemical （quasi-Fermi） potential-gradient theory,are presented over practical ranges of thicknesses of the silicon base and gate oxide. A substantial contri- bution from the longitudinal gradient of the square of the transverse electric field is shown.展开更多
A new photodetector--bipolar junction photogate transistor is presented for CMOS image sensor and its analytical model is also established.With the technical parameter of the 0.6μm CMOS process,the bipolar junction p...A new photodetector--bipolar junction photogate transistor is presented for CMOS image sensor and its analytical model is also established.With the technical parameter of the 0.6μm CMOS process,the bipolar junction photogate transistor is analyzed and simulated.The simulated results illustrate that the bipolar junction photogate transistor has the similar characteristics of the traditional photogate transistor.The photocurrent density of the bipolar junction photogate transistor increases exponentially with the incidence light power due to introducing the injection p+n junction.Its characteristic of blue response is rather improved compared to the traditional photogate transistor that benefits to increase the color photograph made up of the red,the green,and the blue.展开更多
基金supported in part by NIH grants R01 AA016015,K01 DA029643,R21 AA021380 and R21 AA020319the National Alliance for Research on Schizophrenia and Depression(NARSAD)Award 17616the ABMRF/The Foundation for Alcohol Research grant award
基金National Natural Science Foundation of China(T2125008,92263108,92163203,52102292,52003198)Shanghai Rising-Star Program(23QA1409300)Innovation Program of Shanghai Municipal Education Commission(2021-01-07-00-07-E00096)。
文摘Based on Peltier effect,Bi_(2)Te_(3)-based alloy is widely used in commercial solid-state refrigeration at room temperature.The mainstream strategies for enhancing room-temperature thermoelectric performance in Bi_(2)Te_(3)focus on band and microstructure engineering.However,a clear understanding of the modulation of band structure and scattering through such engineering remains still challenging,because the minority carriers compensate partially the overall transport properties for the narrow-gap Bi_(2)Te_(3)at room temperature(known as the bipolar effect).The purpose of this work is to model the transport properties near and far away from the bipolar effect region for Bi_(2)Te_(3)-based thermoelectric material by a two-band model taking contributions of both majority and minority carriers into account.This is endowed by shifting the Fermi level from the conduction band to the valence band during the modeling.A large amount of data of Bi_(2)Te_(3)-based materials is collected from various studies for the comparison between experimental and predicted properties.The fundamental parameters,such as the density of states effective masses and deformation potential coefficients,of Bi_(2)Te_(3)-based materials are quantified.The analysis can help find out the impact factors(e.g.the mobility ratio between conduction and valence bands)for the improvement of thermoelectric properties for Bi_(2)Te_(3)-based alloys.This work provides a convenient tool for analyzing and predicting the transport performance even in the presence of bipolar effect,which can facilitate the development of the narrow-gap thermoelectric semiconductors.
文摘Good performance SiGe power amplifiers applicable to wireless communications are demonstrated.The output power can reach more than 30dBm in class B mode.And in class AB mode,the output power at 1dB compression point ( P 1dB ) is 24dBm,the output third order intercept (TOI) power is 39dBm under V cc of 4V.The highest power added efficiency (PAE) and PAE at 1dB compression point are 34% and 25%,respectively.The adjacent channel power rejection for CDMA signal is more than 42dBc,which complies with IS95 specification.
基金The National High Technology Research and Development Program of China(863 Program)(No.2009AA01Z260)
文摘A monolithic microwave integrated circuit （MMIC） power amplifier （PA） is proposed. It adopts a new on-chip bias circuit, which not only avoids the instability of the direct current bias caused by the change in the power supply and temperature, but also compensates deviations caused by the increase in input power. The bias circuit is a current-mirror configuration, and the feedback circuit helps to maintain bias voltage at a constant level. The gain of the feedback circuit is improved by the addition of a non-inverting amplifier within the feedback circuit. A shunt capacitor at the base node of the active bias transistor enhances the linearity of the PA. The chip is fabricated in an InGaP/GaAs heterojunction bipolar transistor （HBT） process. Measured results exhibit a 26. 6-dBm output compression point, 33.6% power-added efficiency （PAE） and - 40.2 dBc adjacent channel power ratio （ACPR） for wide-band code division multiple access （W-CDMA） applications.
文摘An emitter self-aligned InP-based single heterojunction bipolar transistor with a cutoff frequency （fT） of 162GHz is reported. The emitter size is 0.8μm × 12μm, the maximum DC gain is 120, the offset voltage is 0.10V,and the typical breakdown voltage at Ic = 0. 1μA is 3.8V. This device is suitable for high-speed low-power applications,such as OEIC receivers and analog-to-digital converters.
文摘An InP-based single-heterojunction bipolar transistor （SHBT） with base μ-bndge and emitter air-bridge is reported. Because those bridges reduce parasitic capacitance greatly, the cutoff frequency fT of the 2μm ×12.5μm InP SHBT without de-embedding reaches 178GHz. It is critical in high-speed low power applications,such as OEIC receivers and analog-to-digital converters.
文摘Super performance InGaP/GaAs heterojunction bipolar transistors (HBTs) with hexagonal emitter are described.The fabricated HBT shows excellent DC characteristics with low V CE offset voltage (<0 15V) and low knee voltage (<0 5V).Over 14V of the collector base breakdown voltage BV CBO and over 9V of the collector emitter breakdown voltage BV CEO are obtained.For a self aligned InGaP/GaAs HBT with 2μm×10μm emitter area,the f T is extrapolated to 92GHz and f max is extrapolated to 105GHz.These great values are obtained due to the hexagonal emitter and laterally etched undercut (LEU) of collector,indicating the great potential of InGaP/GaAs HBTs for high speed digital circuit and microwave power applications.
文摘The alloy temperature dependence of Voffset and Rcontact is studied, and an optimal alloy temperature range for the best trade-off between Voffset and Rcontact, is given for thin base HBTs. In addition,the reason for the high Voffset at high alloy temperature is interpreted using Schottky clamped theory. The lower Voffset of our U-shaped emitter HBT than that of traditional strip emitter HBTs is explained.
文摘This paper describes the bipolar field-effect transistor （BiFET） and its theory. Analytical solution is ob- tained from partitioning the two-dimensional transistor into two one-dimensional transistors. The analysis employs the parametric surface-electric-potential and the electrochemical （quasi-Fermi） potential-gradient driving force to compute the current. Output and transfer D. C. current and conductance versus voltage are presented over practi- cal ranges of terminal D. C. voltages and device parameters. Electron and hole surface channel currents are pres- ent simultaneously, a new feature which could provide circuit functions in one physical transistor such as the CMOS inverter and SRAM memory.
文摘This paper describes the drift-diffusion theory of the bipolar field-effect transistor （BiFET） with two identical and connected metal-oxide-silicon-gates （MOS-gates） on a thin-pure-base. Analytical solution is obtained by partitioning the two-dimensional transistor into two one-dimensional problems coupled by the parametric sur- face-electric-potential. Total and component output and transfer currents and conductances versus D. C. voltages from the drift-diffusion theory, and their deviations from the electrochemical （quasi-Fermi） potential-gradient theory,are presented over practical ranges of thicknesses of the silicon base and gate oxide. A substantial contri- bution from the longitudinal gradient of the square of the transverse electric field is shown.
文摘A new photodetector--bipolar junction photogate transistor is presented for CMOS image sensor and its analytical model is also established.With the technical parameter of the 0.6μm CMOS process,the bipolar junction photogate transistor is analyzed and simulated.The simulated results illustrate that the bipolar junction photogate transistor has the similar characteristics of the traditional photogate transistor.The photocurrent density of the bipolar junction photogate transistor increases exponentially with the incidence light power due to introducing the injection p+n junction.Its characteristic of blue response is rather improved compared to the traditional photogate transistor that benefits to increase the color photograph made up of the red,the green,and the blue.
