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Effects of post-annealed floating gate on the performance of AlGaN/GaN heterostructure field-effect transistors
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作者 崔鹏 +2 位作者 付晨 刘艳 吕元杰 《中国物理B:英文版》 SCIE EI CAS CSCD 2017年第12期456-461,共6页
Influence of the AlGaN barrier thickness on polarization Coulomb field scattering in an AlGaN/AlN/GaN heterostructure field-effect transistor
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作者 吕元杰 冯志红 +8 位作者 顾国栋 尹甲运 房玉龙 王元刚 谭鑫 周幸叶 冀子武 蔡树 《中国物理B:英文版》 SCIE EI CAS CSCD 2015年第8期534-538,共5页
In this study rectangular AlGaN/AlN/GaN heterostructure field-effect transistors(HFETs) with 22-nm and 12-nm AlGaN barrier layers are fabricated, respectively. Using the measured capacitance–voltage and current–volt... In this study rectangular AlGaN/AlN/GaN heterostructure field-effect transistors(HFETs) with 22-nm and 12-nm AlGaN barrier layers are fabricated, respectively. Using the measured capacitance–voltage and current–voltage characteristics of the prepared devices with different Schottky areas, it is found that after processing the device, the polarization Coulomb field(PCF) scattering is induced and has an important influence on the two-dimensional electron gas electron mobility.Moreover, the influence of PCF scattering on the electron mobility is enhanced by reducing the AlGaN barrier thickness.This leads to the quite different variation of the electron mobility with gate bias when compared with the AlGaN barrier thickness. This mainly happens because the thinner AlGaN barrier layer suffers from a much stronger electrical field when applying a gate bias, which gives rise to a stronger converse piezoelectric effect. 展开更多
关键词 ALGAN/ALN/GAN barrier layer thickness electron mobility POLARIZATION COULOMB field SCATTERING
Improvement of switching characteristics by substrate bias in AlGaN/AlN/GaN heterostructure field effect transistors
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作者 杨铭 +4 位作者 赵景涛 王玉堂 李志远 吕元杰 冯志红 《中国物理B:英文版》 SCIE EI CAS CSCD 2015年第11期406-409,共4页
A simple and effective approach to improve the switching characteristics of Al Ga N/Al N/Ga N heterostructure field effect transistors(HFETs) by applying a voltage bias on the substrate is presented. With the increase... A simple and effective approach to improve the switching characteristics of Al Ga N/Al N/Ga N heterostructure field effect transistors(HFETs) by applying a voltage bias on the substrate is presented. With the increase of the substrate bias,the OFF-state drain current is much reduced and the ON-state current keeps constant. Both the ON/OFF current ratio and the subthreshold swing are demonstrated to be greatly improved. With the thinned substrate, the improvement of the switching characteristics with the substrate bias is found to be even greater. The above improvements of the switching characteristics are attributed to the interaction between the substrate bias induced electrical field and the bulk traps in the Ga N buffer layer, which reduces the conductivity of the Ga N buffer layer. 展开更多
关键词 异质结场效应晶体管 衬底偏压 开关特性 偏置 HFET 相互作用 流状态 电流比
Comparison of electrical characteristic between AIN/GaN and AIGaN/GaN heterostructure Schottky diodes
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作者 吕元杰 冯志红 +5 位作者 顾国栋 敦少博 尹甲运 韩婷婷 蔡树 《中国物理B:英文版》 SCIE EI CAS CSCD 2014年第2期421-425,共5页
Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated.Based on the measured current–voltage and capacitance–voltage curves,the electrical characteristics of AlN/GaN Schottky diode,such as ... Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated.Based on the measured current–voltage and capacitance–voltage curves,the electrical characteristics of AlN/GaN Schottky diode,such as Schottky barrier height,turn-on voltage,reverse breakdown voltage,ideal factor,and the current-transport mechanism,are analyzed and then compared with those of an AlGaN/GaN diode by self-consistently solving Schrdinger’s and Poisson’s equations.It is found that the dislocation-governed tunneling is dominant for both AlN/GaN and AlGaN/GaN Schottky diodes.However,more dislocation defects and a thinner barrier layer for AlN/GaN heterostructure results in a larger tunneling probability,and causes a larger leakage current and lower reverse breakdown voltage,even though the Schottky barrier height of AlN/GaN Schottky diode is calculated to be higher that of an AlGaN/GaN diode. 展开更多
关键词 肖特基二极管 AlGaN 电特性 异质 AIN 反向击穿电压 电压曲线 势垒高度
Different influences of Schottky metal on the strain and relative permittivity of barrier layer between AIN/GaN and AIGaN/GaN heterostructure Schottky diodes
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作者 吕元杰 冯志红 +9 位作者 顾国栋 敦少博 尹甲运 王元刚 徐鹏 韩婷婷 宋旭波 蔡树 栾崇彪 《中国物理B:英文版》 SCIE EI CAS CSCD 2014年第2期426-430,共5页
Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated.Based on the measured current–voltage and capacitance-voltage curves,the polarization sheet charge density and relative permittivity ar... Ni/Au Schottky contacts on AlN/GaN and AlGaN/GaN heterostructures are fabricated.Based on the measured current–voltage and capacitance-voltage curves,the polarization sheet charge density and relative permittivity are analyzed and calculated by self-consistently solving Schrdinger’s and Poisson’s equations.It is found that the values of relative permittivity and polarization sheet charge density of AlN/GaN diode are both much smaller than the ones of AlGaN/GaN diode,and also much lower than the theoretical values.Moreover,by fitting the measured forward I–V curves,the extracted dislocations existing in the barrier layer of the AlN/GaN diode are found to be much more than those of the AlGaN/GaN diode.As a result,the conclusion can be made that compared with AlGaN/GaN diode the Schottky metal has an enhanced influence on the strain of the extremely thinner AlN barrier layer,which is attributed to the more dislocations. 展开更多
关键词 肖特基二极管 AlGaN 相对介电常数 阻挡层 基金属 应变 异质 AIN
Influence of the channel electric field distribution on the polarization Coulomb field scattering in In0.18Al0.82N/AIN/GaN heterostructure field-effect transistors
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作者 吕元杰 冯志红 +7 位作者 郭红雨 顾国栋 尹甲运 王元刚 徐鹏 宋旭波 蔡树 《中国物理B:英文版》 SCIE EI CAS CSCD 2014年第4期517-520,共4页
By making use of the quasi-two-dimensional(quasi-2D) model, the current–voltage(I–V) characteristics of In0.18Al0.82N/AlN/GaN heterostructure field-effect transistors(HFETs) with different gate lengths are simulated... By making use of the quasi-two-dimensional(quasi-2D) model, the current–voltage(I–V) characteristics of In0.18Al0.82N/AlN/GaN heterostructure field-effect transistors(HFETs) with different gate lengths are simulated based on the measured capacitance–voltage(C–V) characteristics and I–V characteristics. By analyzing the variation of the electron mobility for the two-dimensional electron gas(2DEG) with electric field, it is found that the different polarization charge distributions generated by the different channel electric field distributions can result in different polarization Coulomb field scatterings. The difference between the electron mobilities primarily caused by the polarization Coulomb field scatterings can reach up to 1522.9 cm2/V·s for the prepared In0.18Al0.82N/AlN/GaN HFETs. In addition, when the 2DEG sheet density is modulated by the drain–source bias, the electron mobility presents a peak with the variation of the 2DEG sheet density,the gate length is smaller, and the 2DEG sheet density corresponding to the peak point is higher. 展开更多
关键词 异质结场效应晶体管 电场分布 库仑场 散射 偏振 电子迁移率 二维电子气 2DEG
Comparison for the carrier mobility between the III-V nitrides and AIGaAs/GaAs heterostructure field-effect transistors
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作者 栾崇彪 +4 位作者 吕元杰 冯志红 赵景涛 周阳 杨铭 《半导体学报:英文版》 EI CAS CSCD 2014年第9期65-70,共6页
Using the measured capacitance–voltage curves of Ni/Au Schottky contacts with different areas and the current–voltage characteristics for the AlGaAs/GaAs, AlGaN/AlN/GaN and In0.18Al0.82N/AlN/GaN heterostructure fiel... Using the measured capacitance–voltage curves of Ni/Au Schottky contacts with different areas and the current–voltage characteristics for the AlGaAs/GaAs, AlGaN/AlN/GaN and In0.18Al0.82N/AlN/GaN heterostructure field-effect transistors (HFETs) at low drain–source voltage,the two-dimensional electron gas (2DEG) electron mobility for the prepared HFETs was calculated and analyzed. It was found that there is an obvious difference for the variation trend of the mobility curves between the III–V nitride HFETs and the AlGaAs/GaAs HFETs. In the III–V nitride HFETs, the variation trend for the curves of the 2DEG electron mobility with the gate bias is closely related to the ratio of the gate length to the drain-to-source distance. While the ratio of the gate length to the drainto-source distance has no effect on the variation trend for the curves of the 2DEG electron mobility with the gate bias in the AlGaAs/GaAs HFETs. The reason is attributed to the polarization Coulomb field scattering in the III–V nitride HFETs. 展开更多
关键词 异质结场效应晶体管 氮化物 砷化镓 载流子迁移 电子迁移率 ALGAN 电压曲线 2DEG
Effect of the side-Ohmic contact processing on the polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors
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作者 赵景涛 +4 位作者 栾崇彪 杨铭 周阳 吕元杰 冯志红 《半导体学报:英文版》 EI CAS CSCD 2014年第12期28-31,共4页
Using the measured capacitance–voltage and current–voltage characteristics of the rectangular AlN/GaN heterostructure field-effect transistors(HFETs) with the side-Ohmic contacts, it was found that the polarization ... Using the measured capacitance–voltage and current–voltage characteristics of the rectangular AlN/GaN heterostructure field-effect transistors(HFETs) with the side-Ohmic contacts, it was found that the polarization Coulomb field scattering in the AlN/GaN HFETs was greatly weakened after the side-Ohmic contact processing, however, it still could not be ignored. It was also found that, with side-Ohmic contacts, the polarization Coulomb field scattering was much stronger in AlN/GaN HFETs than in Al GaN/AlN/GaN and In0:17Al0:83N/AlN/GaN HFETs, which was attributed to the extremely thinner barrier layer and the stronger polarization of the AlN/GaN heterostructure. 展开更多
关键词 场效应晶体管 欧姆接触 接触处理 ALN GAN 库仑场 散射 偏振
The influence of the channel electric field distribution on the polarization Coulomb field scattering in AlN/GaN heterostructure field-effect transistors
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作者 于英霞 +4 位作者 吕元杰 冯志红 栾崇彪 杨铭 王玉堂 《半导体学报:英文版》 EI CAS CSCD 2014年第12期48-52,共5页
Based on the measured capacitance–voltage(C–V) curves and current–voltage(I–V) curves for the prepared differently-sized AlN/GaN heterostructure field-effect transistors(HFETs), the I–V characteristics of the AlN... Based on the measured capacitance–voltage(C–V) curves and current–voltage(I–V) curves for the prepared differently-sized AlN/GaN heterostructure field-effect transistors(HFETs), the I–V characteristics of the AlN/GaN HFETs were simulated using the quasi-two-dimensional(quasi-2D) model. By analyzing the variation in the electron mobility for the two-dimensional electron gas(2DEG) with the channel electric field, it is found that the different polarization charge distribution generated by the different channel electric field distribution can result in different polarization Coulomb field(PCF) scattering. The 2DEG electron mobility difference is mostly caused by the PCF scattering which can reach up to 899.6 cm2/(V·s)(sample a), 1307.4 cm2/(V·s)(sample b),1561.7 cm2/(V s)(sample c) and 678.1 cm2/(V·s)(sample d), respectively. When the 2DEG sheet density is modulated by the drain–source bias, the electron mobility for samples a, b and c appear to peak with the variation of the 2DEG sheet density, but for sample d, no peak appears and the electron mobility rises with the increase in the2 DEG sheet density. 展开更多
关键词 场效应晶体管 电场分布 ALN GAN 库仑场 散射 信道 偏振
Effects of GaN cap layer thickness on an AlN/GaN heterostructure
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作者 赵景涛 +3 位作者 栾崇彪 吕元杰 冯志宏 杨铭 《中国物理B:英文版》 SCIE EI CAS CSCD 2014年第12期404-407,共4页
In this study, we investigate the effects of Ga N cap layer thickness on the two-dimensional electron gas(2DEG)electron density and 2DEG electron mobility of Al N/Ga N heterostructures by using the temperature-depende... In this study, we investigate the effects of Ga N cap layer thickness on the two-dimensional electron gas(2DEG)electron density and 2DEG electron mobility of Al N/Ga N heterostructures by using the temperature-dependent Hall measurement and theoretical fitting method. The results of our analysis clearly indicate that the Ga N cap layer thickness of an Al N/Ga N heterostructure has influences on the 2DEG electron density and the electron mobility. For the Al N/Ga N heterostructures with a 3-nm Al N barrier layer, the optimized thickness of the Ga N cap layer is around 4 nm and the strained a-axis lattice constant of the Al N barrier layer is less than that of Ga N. 展开更多
关键词 覆盖层厚度 异质结构 ALN GAN 电子迁移率 2DEG 电子密度 温度依赖性
Influence of drain bias on the electron mobility in AIGaN/AIN/GaN heterostructure field-effect transistors
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作者 吕元杰 冯志红 +8 位作者 蔡树 敦少博 刘波 尹甲运 张雄文 房玉龙 孟令国 栾崇彪 《中国物理B:英文版》 SCIE EI CAS CSCD 2013年第6期518-521,共4页
Using measured capacitance-voltage curves and current-voltage characteristics for the AlGaN/AlN/GaN heterostructure field-effect transistors with different gate lengths and drain-to-source distances,the influence of d... Using measured capacitance-voltage curves and current-voltage characteristics for the AlGaN/AlN/GaN heterostructure field-effect transistors with different gate lengths and drain-to-source distances,the influence of drain bias on the electron mobility is investigated.It is found that below the knee voltage the longitudinal optical(LO) phonon scattering and interface roughness scattering are dominant for the sample with a large ratio of gate length to drain-to-source distance(here 4/5),and the polarization Coulomb field scattering is dominant for the sample with a small ratio(here 1/5).However,the above polarization Coulomb field scattering is weakened in the sample with a small drain-to-source distance(here 20 μm) compared with the one with a large distance(here 100 μm).This is due to the induced strain in the AlGaN layer caused by the drain bias. 展开更多
Directly extracting both threshold voltage and series resistance from the conductance-voltage curve of an AlGaN/GaN Schottky diode
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作者 吕元杰 冯志红 +7 位作者 顾国栋 敦少博 尹甲运 韩婷婷 盛百城 蔡树 刘波 《中国物理B:英文版》 SCIE EI CAS CSCD 2013年第7期426-429,共4页
An Ni/Au Schottky contact on an AlGaN/GaN heterostructure has been prepared. By using the peak-conductance model, the threshold voltage and the series resistance of the AlGaN/GaN diode are simultaneously extracted fro... An Ni/Au Schottky contact on an AlGaN/GaN heterostructure has been prepared. By using the peak-conductance model, the threshold voltage and the series resistance of the AlGaN/GaN diode are simultaneously extracted from the conductance-voltage (G-V) curve and found to be in good agreement with the ones obtained by using the capacitance-voltage (C-V) curve integration and the plot of dV/d(ln I) versus current I. Thus, a method of directly and simultaneously extracting both the threshold voltage and the series resistance from the conductance-voltage curve for the AlGaN/GaN Schottky diode is developed. 展开更多
关键词 肖特基二极管 AlGaN 电压曲线 电导模型 串联电阻 阈值电压 解压 肖特基接触
Influence of Schottky drain contacts on the strained AlGaN barrier layer of AlGaN/AlN/GaN heterostructure field-effect transistors
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作者 曹芝芳 +2 位作者 吕元杰 栾崇彪 王占国 《中国物理B:英文版》 SCIE EI CAS CSCD 2013年第4期394-398,共5页
Rectangular Schottky drain AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate contact areas and conventional AlGaN/AlN/GaN HFETs as control were both fabricated with same size. It was f... Rectangular Schottky drain AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with different gate contact areas and conventional AlGaN/AlN/GaN HFETs as control were both fabricated with same size. It was found there is a significant difference between Schottky drain AlGaN/AlN/GaN HFETs and the control group both in drain series resistance and in two-dimensional electron gas (2DEG) electron mobility in the gate-drain channel. We attribute this to the different influence of Ohmic drain contacts and Schottky drain contacts on the strained AlGaN barrier layer. For conventional AlGaN/AlN/GaN HFETs, annealing drain Ohmic contacts gives rise to a strain variation in the AlGaN barrier layer between the gate contacts and the drain contacts, and results in strong polarization Coulomb field scattering in this region. In Schottky drain AlGaN/AlN/GaN HFETs, the strain in the AlGaN barrier layer is distributed more regularly. 展开更多
关键词 异质结场效应晶体管 ALGAN 应变变化 肖特基 势垒层 AlN HFET 欧姆接触
Electron mobility in the linear region of an AlGaN/AlN/GaN heterostructure field-effect transistor
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作者 于英霞 +3 位作者 栾崇彪 王玉堂 陈弘 王占国 《中国物理B:英文版》 SCIE EI CAS CSCD 2013年第6期530-535,共6页
We simulate the current-voltage(I-V) characteristics of AlGaN/AlN/GaN heterostructure field-effect transistors(HFETs) with different gate lengths using the quasi-two-dimensional(quasi-2D) model.The calculation results... We simulate the current-voltage(I-V) characteristics of AlGaN/AlN/GaN heterostructure field-effect transistors(HFETs) with different gate lengths using the quasi-two-dimensional(quasi-2D) model.The calculation results obtained using the modified mobility model are found to accord well with the experimental data.By analyzing the variation of the electron mobility for the two-dimensional electron gas(2DEG) with the electric field in the linear region of the AlGaN/AlN/GaN HFET I-V output characteristics,it is found that the polarization Coulomb field scattering still plays an important role in the electron mobility of AlGaN/AlN/GaN HFETs at the higher drain voltage and channel electric field.As drain voltage and channel electric field increase,the 2DEG density reduces and the polarization Coulomb field scattering increases,as a result,the 2DEG electron mobility decreases. 展开更多
A simple method of extracting the polarization charge density in the A1GaN/GaN heterostructure from current-voltage and capacitance-voltage characteristics
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作者 吕元杰 +4 位作者 于英霞 孟令国 曹芝芳 栾崇彪 王占国 《中国物理B:英文版》 SCIE EI CAS CSCD 2012年第9期436-439,共4页
An Ni Schottky contact on the AlGaN/GaN heterostructure is fabricated. The flat-band voltage for the Schottky contact on the AlGaN/GaN heterostructure is obtained from the forward current-voltage characteristics. With... An Ni Schottky contact on the AlGaN/GaN heterostructure is fabricated. The flat-band voltage for the Schottky contact on the AlGaN/GaN heterostructure is obtained from the forward current-voltage characteristics. With the measured capacitance-voltage curve and the flat-band voltage, the polarization charge density in the AlGaN/GaN heterostructure is investigated, and a simple formula for calculating the polarization charge density is obtained and analyzed. With the approach described in this paper, the obtained polarization charge density agrees well with the one calculated by self-consistently solving Schrodinger’s and Poisson’s equations. 展开更多
关键词 电荷密度 异质结构 电压特性 极化 电流 电容 肖特基接触 提取
Determination of the series resistance under the Schottky contacts of AlGaN/AlN/GaN Schottky barrier diodes
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作者 曹芝芳 +4 位作者 吕元杰 栾崇彪 于英霞 陈弘 王占国 《中国物理:英文版》 SCIE EI CAS CSCD 2012年第1期 414-418,共5页
Rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) were fabricated,and the gate and the source of the HFETs consisted of AlGaN/AlN/GaN Schottky barrier diodes (SBDs).Based on the measured forwa... Rectangular AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) were fabricated,and the gate and the source of the HFETs consisted of AlGaN/AlN/GaN Schottky barrier diodes (SBDs).Based on the measured forward current-voltage and the capacitance-voltage characteristics of the AlGaN/AlN/GaN SBDs,the series resistance under the Schottky contacts (RS) was calculated using the method of power consumption,which has been proved to be valid.Finally,the method of power consumption for calculating R S was successfully used to study the two-dimensional electron gas electron mobility for a series of circular AlGaN/AlN/GaN SBDs.It is shown that the series resistance under the Schottky contacts cannot be neglected and is important for analysing and characterizing the AlGaN/AlN/GaN SBDs and the AlGaN/AlN/GaN HFETs. 展开更多
关键词 肖特基接触 串联电阻 氮化镓 氮化铝 肖特基二极管 肖特基势垒二极管 ALGAN 测定
AlGaN/GaN HEMT势垒层厚度影响的模拟及优化
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作者 申艳芬 +3 位作者 李惠 张明华 魏晓珂 刘岩 《微纳电子技术》 CAS 北大核心 2011年第3期150-154,193共6页
完成了对AlGaN/GaN高电子迁移率晶体管(HEMT)的结构设计及器件物理特性的验证等工作。使用TCAD软件完成了该器件直流特性及微波特性等性能的模拟。建立该器件的极化效应模型是本项研究的重点。完成了对异质结条件下诸多模型参数的筛... 完成了对AlGaN/GaN高电子迁移率晶体管(HEMT)的结构设计及器件物理特性的验证等工作。使用TCAD软件完成了该器件直流特性及微波特性等性能的模拟。建立该器件的极化效应模型是本项研究的重点。完成了对异质结条件下诸多模型参数的筛选及修正,得到了符合理论的模拟结果。器件特性的验证与优化基于势垒层厚度h的变化展开,研究结果显示:漏极电流随h值的增加而增加,当h值超过40nm时,因二维电子气浓度上升缓慢而使漏极电流趋于饱和;跨导随h值的减小而增大,h每降低10nm,跨导约增大37mS/mm;势垒层厚度对高频特性的影响较小。 展开更多
关键词 ALGAN/GAN 高电子迁移率晶体管(HEMT) 二维电子气(2DEG) 极化效应 器件模型
影响AlGaN/GaN HFET器件二维电子气的若干因素
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作者 张明华 +3 位作者 李惠 申艳芬 魏晓珂 刘岩 《微纳电子技术》 CAS 北大核心 2011年第4期225-229,共5页
基于Sentaurus Workbench(SWB)TCAD可制造性设计平台进行AlGaN/GaN器件的结构设计和仿真,并对影响二维电子气的重要参数因素进行了研究及优化,诸如AlGaN势垒层中Al组分x、AlGaN势垒层厚度h、应变弛豫度r和栅偏压Vg等因素。参数相关性... 基于Sentaurus Workbench(SWB)TCAD可制造性设计平台进行AlGaN/GaN器件的结构设计和仿真,并对影响二维电子气的重要参数因素进行了研究及优化,诸如AlGaN势垒层中Al组分x、AlGaN势垒层厚度h、应变弛豫度r和栅偏压Vg等因素。参数相关性的制约结果,无疑会反映在对器件物理特性的制约及影响上。研究结果表明,在一定条件下增大势垒层中Al组分和势垒层厚度可以提高器件的电流传输特性。然而随着二者的不断增大将会引起应变弛豫的发生,而应变弛豫的发生会降低器件的性能。 展开更多
关键词 ALGAN/GAN 异质结场效应晶体管(HFET) 二维电子气(2DEG) 自发极化 压电极化
Influence of thermal stress on the relative permittivity of the AlGaN barrier layer in an AlGaN/GaN heterostructure Schottky contacts
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作者 吕元杰 +5 位作者 张宇 孟令国 曹芝芳 栾崇彪 陈弘 王占国 《中国物理:英文版》 SCIE EI CAS CSCD 2011年第9期 350-354,共5页
Ni Schottky contacts on AlGaN/GaN heterostructures were fabricated.Some samples were thermally treated in a furnace with N 2 ambience at 600 C for different times (0.5 h,4.5 h,10.5 h,18 h,33 h,48 h,and 72 h),the other... Ni Schottky contacts on AlGaN/GaN heterostructures were fabricated.Some samples were thermally treated in a furnace with N 2 ambience at 600 C for different times (0.5 h,4.5 h,10.5 h,18 h,33 h,48 h,and 72 h),the others were thermally treated for 0.5 h at different temperatures (500℃,600℃,700℃,and 800℃).With the measured current-voltage (I-V) and capacitance-voltage (C-V) curves and by self-consistently solving Schrodinger’s and Poisson’s equations,we found that the relative permittivity of the AlGaN barrier layer was related to the piezoelectric and the spontaneous polarization of the AlGaN barrier layer.The relative permittivity was in proportion to the strain of the AlGaN barrier layer.The relative permittivity and the strain reduced with the increased thermal stress time until the AlGaN barrier totally relaxed (after 18 h at 600℃ in the current study),and then the relative permittivity was almost a constant with the increased thermal stress time.When the sample was treated at 800℃ for 0.5 h,the relative permittivity was less than the constant due to the huge diffusion of the contact metal atoms.Considering the relation between the relative permittivity of the AlGaN barrier layer and the converse piezoelectric effect,the conclusion can be made that a moderate thermal stress can restrain the converse piezoelectric effect and can improve the stability of AlGaN/GaN heterostructure devices. 展开更多
关键词 相对介电常数 异质结器件 肖特基接触 热应力 屏障 逆压电效应 时间常数 泊松方程
Influence of thermal stress on the characteristic parameters of AlGaN/GaN heterostructure Schottky contacts
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作者 吕元杰 +5 位作者 张宇 孟令国 曹芝芳 栾崇彪 陈弘 王占国 《中国物理B:英文版》 SCIE EI CAS CSCD 2011年第4期430-434,共5页
Ni Schottky contacts on AlGaN/GaN heterostructures have been fabricated. The samples are then thermally treated in a furnace with N 2 ambient at 600 C for different times (0.5,4.5,10.5,18,33,48 and 72h). Current-volta... Ni Schottky contacts on AlGaN/GaN heterostructures have been fabricated. The samples are then thermally treated in a furnace with N 2 ambient at 600 C for different times (0.5,4.5,10.5,18,33,48 and 72h). Current-voltage (I-V ) and capacitance-voltage (C-V ) relationships are measured,and Schrodinger’s and Poisson’s equations are self-consistently solved to obtain the characteristic parameters related to AlGaN/GaN heterostructure Schottky contacts: the two-dimensional electron gas (2DEG) sheet density,the polarization sheet charge density,the 2DEG distribution in the triangle quantum well and the Schottky barrier height for each thermal stressing time. Most of the above parameters reduce with the increase of stressing time,only the parameter of the average distance of the 2DEG from the AlGaN/GaN interface increases with the increase of thermal stressing time. The changes of the characteristic parameters can be divided into two stages. In the first stage the strain in the AlGaN barrier layer is present. In this stage the characteristic parameters change rapidly compared with those in the second stage in which the AlGaN barrier layer is relaxed and no strain is present. 展开更多
关键词 ALGAN 肖特基接触 异质结构 特性参数 热应力 二维电子气 泊松方程 板材密度
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