AlGaN/GaN基HEMT器件的研究进展(英文)

由于AlGaN具有高的击穿电场(3 MV/cm,是GaAs的7.5倍),且在AlGaN/GaN异质结处存在高浓度的极化诱导二维电子气,AlGaN基高电子迁移率晶体管是目前最适合应用于微波大功率放大领域的器件。着重对影响高频大功率AlGaN/GaN性能的材料结构和器件制作进行了阐述。     

AlGaN/GaN材料HEMT器件优化分析与I-V特性

在考虑Al Ga N / Ga N异质结中的压电极化和自发极化效应的基础上,自洽求解了垂直于沟道方向的薛定谔方程和泊松方程.通过模拟计算,研究了Al Ga N / Ga N HEMT器件掺杂层Al的组分、厚度、施主掺杂浓度以及栅偏压对二维电子气特性的影响.用准二维物理模型计算了Al Ga N/ Ga N HEMT器件的输出特性,给出了相应的饱和电压和阈值电压,并对计算结果和Al Ga N/ Ga N HEMT器件的结构优化进行了分析.     

AlN阻挡层对AlGaN/GaN HEMT器件的影响

利用低压MOCVD技术在蓝宝石衬底上生长了AlGaN/GaN异质结和AlGaN/AlN/GaN异质结二维电子气材料,采用相同器件工艺制造出了AlGaN/GaN HEMT器件和AlGaN/AlN/GaN HEMT器件.通过对两种不同器件的比较和讨论,研究了AlN阻挡层的增加对AlGaN/GaN HEMT器件性能的影响.     

AlGaN/GaN材料HEMT器件优化分析与I-V特性

在考虑AlGaN/GaN异质结中的压电极化和自发极化效应的基础上,自洽求解了垂直于沟道方向的薛定谔方程和泊松方程.通过模拟计算,研究了AlGaN/GaN HEMT器件掺杂层Al的组分、厚度、施主掺杂浓度以及栅偏压对二维电子气特性的影响.用准二维物理模型计算了AlGaN/GaN HEMT器件的输出特性,给出了相应的饱和电压和阈值电压,并对计算结果和AlGaN/GaN HEMT器件的结构优化进行了分析.     

GaN基HEMT器件的优化设计北大核心CSCD

针对氮化镓(GaN)高电子迁移率晶体管(HEMT)器件自热效应以及电流崩塌效应导致器件性能退化和失效的问题,研究了通过合理改变器件参数尺寸优化GaN基HEMT器件的设计,提高器件性能。通过仿真软件模拟了器件各参数对于GaN器件电学性能的影响,分析了不同衬底构成对GaN HEMT器件自热效应的影响,系统研究了GaN HEMT器件相关参数改变对自热效应及器件电学性能的影响。结果表明:Si及金刚石组成的衬底中减小Si层的厚度有利于减小器件的自热效应,降低有源区最高温度。为提高器件性能以及进一步优化GaN基HEMT器件设计提供了一定的理论参考。     

高跨导AlGaN/GaN HEMT器件

报道了生长在蓝宝石衬底上的AlGaN/GaN HEMT器件的制造工艺以及在室温下器件的性能.器件的栅长为1.0μm,源漏间距为4.0μm.器件的最大电流密度达到1000mA/mm,最大跨导高达198mS/mm,转移特性曲线表现出增益带宽较宽的特点.同时由所测得的S参数推出栅长为1.0μm器件的截止频率(fT)和最高振荡频率(fmax)分别为18.7GHz和19.1GHz.     

高跨导AlGaN/GaN HEMT器件

报道了生长在蓝宝石衬底上的AlGaN/GaNHEMT器件的制造工艺以及在室温下器件的性能.器件的栅长为1 0 μm ,源漏间距为4 0 μm .器件的最大电流密度达到1 0 0 0mA/mm ,最大跨导高达1 98mS/mm ,转移特性曲线表现出增益带宽较宽的特点.同时由所测得的S参数推出栅长为1 0 μm器件的截止频率(fT)和最高振荡频率(fmax)分别为1 8 7GHz和1 9 1GHz.     

AIGaN／GaN HEMT高温特性的研究进展

回顾了在高温条件下AIGaN／GaN HEMT器件特性的研究进展。发现2DEG的高温特性是影响器件高温性能的根本内在因素，且外延材料的缺陷、衬底及其器件的封装形式也影响器件的高温特性。最后总结了适合高温下工作的AIGaN／GaN HEMT的改进方法。     

基于蓝宝石衬底的高性能AlGaN/GaN二维电子气材料与HEMT器件

利用低压MOCVD技术在蓝宝石衬底上生长了高性能的Al Ga N/Ga N二维电子气(2 DEG)材料,室温和77K温度下的电子迁移率分别为94 6和2 5 78cm2 /(V·s) ,室温和77K温度下2 DEG面密度分别为1.3×10 1 3和1.2 7×10 1 3cm- 2 .并利用Al Ga N/Ga N二维电子气材料制造出了高性能的HEMT器件,栅长为1μm,源漏间距为4 μm,最大电流密度为4 85 m A/mm(VG=1V) ,最大非本征跨导为170 m S/mm(VG=0 V) ,截止频率和最高振荡频率分别为6 .7和2 4 GHz     

Performance of commercial foundry-level AlGaN/GaN HEMTs after hot electron stressing

The performance degradation of commercial foundry level GaN HEMTs placed under a constant-power drain voltage step-stress test has been studied. By utilizing electroluminescence measurement techniques to optimize hot electron stress testing conditions (Meneghini, 2012), no significant permanent changes in saturation current (I_dss), transconductance (Gm), and threshold voltage (V_th) can be seen after stress testing of drain voltages from 30 V up to 200 V. We observe little permanent degradation due to hot electron effects in GaN HEMTs at these extreme operating conditions and it is inferred that other considerations, such as key dimensions in channel or peak electric field (Chynoweth, 1958; Zhang and Singh, 2001) [2,3], are more relevant to physics of failure than drain bias alone.     

AlGaN/GaN HEMT的B+注入隔离

报道了利用B+注入实现AlGaN/GaN HEMT的有源层隔离。通过优化离子注入的能量和剂量,获得了1011Ω/□的隔离电阻,隔离的高阻特性在700°C下保持稳定。分别制作了用B+注入和台面实现隔离的AlGaN/GaN HEMT,测试表明B+注入隔离的器件击穿电压大于70V,相比于台面隔离器件40V的击穿电压有很大提高;B+注入隔离器件电流增益截止频率fT和最大振荡频率fmax分别达到15GHz和38GHz,相比台面隔离器件的12GHz和31GHz有一定程度提高。     

An improved temperature-dependent large signal model of microwave GaN HEMTs

Accurate modeling of the electrothermal effects of GaN electronic devices is critical for reliability design and assessment. In this paper, an improved temperature-dependent model for large signal equivalent circuit modeling of GaN HEMTs is proposed. To accurately describe the thermal effects, a modified nonlinear thermal sub-circuit which is related not only to power dissipation, but also ambient temperature is used to calculate the variations of channel temperature of the device; the temperature-dependent parasitic and intrinsic elements are also taken into account in this model. The parameters of the thermal sub-circuit are extracted by using the numerical finite element method. The results show that better performance can be achieved by using the proposed large signal model in the range of -55 to 125℃ compared with the conventional model with a linear thermal sub-circuit.     

大功率氮化镓基白光LED模组的散热设计

散热设计是大功率发光二极管(LED)模组结构设计的重要环节.首先利用计算流体力学方法对自然对流条件下大功率LED模组的温度场进行了模拟,提出并优化了模组可采用的散热片结构,进而对影响模组散热的其他关键因素进行了分析,结果表明,提高关键封装材料如银胶的热导率能够有效地降低芯片温度,提高芯片温度均匀性;多芯片封装时芯片的整体温度及均匀性相对于单芯片封装皆有改善.优化后的封装结构在5 W电功率注入条件下,芯片结温约60 ℃.     

钝化前表面预处理对AlGaN/GaN HEMTs性能的影响

提出一种新的钝化技术--采用盐酸和氢氟酸混合预处理溶液(HF:HCI:H2O=1:4:20)对AIGaN/GaNHEMTs进行表面预处理后冉淀积Si3N4钝化,研究了新型钝化技术对AlGaN/GaN HEMTs性能的影响并分析其机理.与用常规方法钝化的器件相比,经过表面顶处理再钝化,成功地抑制了 AIGaN/GaN HEMTs肖特基特性的恶化,有效地增强抑制电流崩塌效应的能力,将GaN基HEMTs的输出功率密度提高到5.2W/mm,并展现良好的电学可靠性.通过X射线光电子谱(XPS)检测预处理前后的AIGaN表面,观察到经过预处理后的AIGaN表面氧元素的含量大幅度下降.表面氧元素的含量下降,能有效地降低表面态密度和表面电荷陷阱密度,被认为是提高AIGaN/GaN HEMTs性能的主要原因.     

Al_2O_3/AlGaN/GaN MOSH结构的制备和性能研究

采用激光脉冲沉积法(PLD)在AlGaN/GaN半导体异质结构衬底上沉积Al2O3栅介质层,并对该异质结构的电学性能进行研究。结果表明,Al2O3栅介质层改善了异质结构的界面质量,增强了器件结构的抗击穿电场强度。研究了沉积氧分压对异质结构性能的影响,电流-电压(I-V)测试结果表明,适当氧分压(0.1 Pa)有利于降低栅漏电流。Hall测量和电容-电压(C-V)模拟结果表明,不同的氧分压会改变Al2O3/AlGaN界面处的正电荷密度,从而改变半导体内的二维电子气(2DEG)密度。     

GaN高电子迁移率晶体管高频噪声特性的研究

基于FUKUI噪声模型,分析了GaN高电子迁移率晶体管(HEMT)器件的高频噪声特性,结果表明,由于GaN HEMT具有更高的临界电场和更大的电子饱和速度,与第2代半导体器件(GaAs HEMT等)相比具有更优越的噪声性能.对近10多年来国内外在GaN HEMT低噪声器件及其低噪声功率放大器单片集成电路(MMIC)方面的研究进行了综述,并分析了GaN HEMT在低噪声应用领域目前存在的主要问题及其发展趋势.     

Development and characterization of the thermal behavior of packaged cascode GaN HEMTs

This study investigates the heat generation behavior of packaged normally-on multi-finger AlGaN/GaN high electron mobility transistors (HEMTs) that are cascoded with a low-voltage MOSFET (LVMOS) and a SiC Schottky barrier diode (SBD). By foremost carrying out electro-thermal simulation and related thermal measurements with infrared thermography and Raman spectroscopy for basic 5 mm GaN HEMTs, the location of hot spot in operating device can be obtained. Based on the outcome, further packaged cascode GaN HEMT is analyzed. A hybrid integration of the GaN-HEMT, LVMOS, and SiC SBD are assembled on a directly bonded copper (DBC) substrate in the four-pin metal case TO-257 package. The metal plate is used as both the source terminal and heat sink. The analytical results of thermal investigation are confirmed by comparing them with the infrared thermographic measurements and numerical results obtained from a simulation using Ansys Icepak. For a power dissipation of less than 11.8 W, the peak temperature of the GaN HEMTs is 118.7 °C, obtained from thermal measurements.     

GaN HEMT的温度特性及其应用

对0.25 μm双场板结构GaN HEMT器件的温度特性进行了研究.负载牵引测试结果显示,GaN HEMT增益的温度系数为-0.02 dB/°C、饱和输出功率系数为-0.004 dB/°C.大的增益温度系数结合GaN HEMT 自热效应引起的高温升对实际应用特别是功率MMIC的设计带来了挑战.按常温设计的GaN功率MM...     

Fabrication and characterization of AlGaN/GaN HEMTs with high power gain and efficiency at 8 GHz

State-of-the-art AlGaN/GaN high electron mobility structures were grown on semi-insulating 4H-SiC substrates by MOCVD and X-band microwave power high electron mobility transistors were fabricated and characterized.Hall mobility of 2291.1 cm2/(V·s) and two-dimensional electron gas density of 9.954 × 1012 cm-2 were achieved at 300 K.The HEMT devices with a 0.45-μm gate length exhibited maximum drain current density as high as 1039.6 mA/mm and peak extrinsic transconduct-ance of 229.7 mS/mm.The fT of 30.89 GHz and fmax of 38.71 GHz were measured on the device.Load-pull measurements were performed and analyzed under (-3.5,28) V,(-3.5,34) V and (-3.5,40) V gate/drain direct current bias in class-AB,respectively.The uncooled device showed high linear power gain of 17.04 dB and high power-added efficiency of 50.56％ at 8 GHz when drain biased at (-3.5,28) V.In addition,when drain biased at (-3.5,40) V,the device exhibited a saturation output power dens-ity up to 6.21 W/mm at 8 GHz,with a power gain of 11.94 dB and a power-added efficiency of 39.56％.Furthermore,the low fmax/fT ratio and the variation of the power sweep of the device at 8 GHz with drain bias voltage were analyzed.