fT为350 GHz的InAlN/GaN HFET高频器件研究

采用再生长n+ GaN非合金欧姆接触工艺研制了具有高电流增益截止频率(fT)的InAlN/GaN异质结场效应晶体管 (HFETs),器件尺寸得到有效缩小,源漏间距减小至600 nm.通过优化干法刻蚀和n+ GaN外延工艺,欧姆接触总电阻值达到0.16 Ω·mm,该值为目前金属有机化学气相沉积(MOCVD)方法制备的最低值.采用自对准电子束曝光工艺实现34 nm直栅.器件尺寸的缩小以及欧姆接触的改善,器件电学特性,尤其是射频特性得到大幅提升.器件的开态电阻(Ron)仅为0.41 Ω·mm,栅压1 V下,漏源饱和电流达到2.14 A/mm.此外,器件的电流增益截止频率(fT)达到350 GHz,该值为目前GaN基HFET器件国内报道最高值.     

f_T为350 GHz的InAlN/GaN HFET高频器件研究（英文）

采用再生长n~+GaN非合金欧姆接触工艺研制了具有高电流增益截止频率(f_T)的InAlN/GaN异质结场效应晶体管(HFETs),器件尺寸得到有效缩小,源漏间距减小至600 nm.通过优化干法刻蚀和n~+GaN外延工艺,欧姆接触总电阻值达到0.16Ω·mm,该值为目前金属有机化学气相沉积(MOCVD)方法制备的最低值.采用自对准电子束曝光工艺实现34 nm直栅.器件尺寸的缩小以及欧姆接触的改善,器件电学特性,尤其是射频特性得到大幅提升.器件的开态电阻(R_(on))仅为0.41Ω·mm,栅压1 V下,漏源饱和电流达到2.14 A/mm.此外,器件的电流增益截止频率(f_T)达到350 GHz,该值为目前GaN基HFET器件国内报道最高值.     

电流增益截止频率为236GHz的InAIN/GaN高频HEMT

研制了高电流增益截止频率(fT)的InAlN/GaN高电子迁移率晶体管(HEMT).采用金属有机化学气相沉积(MOCVD)再生长n+GaN非合金欧姆接触工艺将器件源漏间距缩小至600 nm,降低了源、漏寄生电阻,有利于改善器件的寄生效应;使用低压化学气相沉积(LPCVD)生长SiN作为栅下介质,降低了InAlN/GaN HEMT栅漏电;利用电子束光刻实现了栅长为50 nm的T型栅.此外,还讨论了寄生效应对器件fT的影响.测试结果表明,器件的栅漏电为3.8 μA/mm,饱和电流密度为2.5 A/mm,fT达到236 GHz.延时分析表明,器件的寄生延时为0.13 ps,在总延时中所占的比例为19％,优于合金欧姆接触工艺的结果.     

基于60 nm T型栅fT & fmax为170 & 210 GHz 的InAlN/GaN HFETs 器件

基于蓝宝石衬底InAlN/GaN异质结材料研制具有高电流增益截止频率(fT)和最大振荡频率(fmax)的InAlN/GaN异质结场效应晶体管 (HFETs)。基于再生长n GaN欧姆接触工艺实现了器件尺寸的缩小,有效源漏间距(Lsd)缩小至600 nm。此外,采用自对准栅工艺制备60 nm T型栅。由于器件尺寸的缩小,在Vgs= 1 V下,器件最大饱和电流(Ids)达到1.89 A/mm,峰值跨导达到462 mS/mm。根据小信号测试结果,外推得到器件的fT和fmax分别为170 GHz和210 GHz,该频率特性为国内InAlN/GaN HFETs器件频率的最高值。     

基于再生长欧姆接触工艺的220 GHz InAlN/GaN场效应晶体管（英文）

在蓝宝石衬底上研制了具有高电流增益截止频率(f_T)的InAlN/GaN异质结场效应晶体管(HFETs).基于MOCVD外延n+-GaN欧姆接触工艺实现了器件尺寸的缩小,有效源漏间距(Lsd)缩小至600 nm.此外,采用自对准工艺制备了50 nm直栅.由于器件尺寸的缩小,Vgs=1 V下器件最大饱和电流(I_(ds))达到2.11 A/mm,峰值跨导达到609 mS/mm.根据小信号测试结果,外推得到器件的fT和最大振荡频率(fmax)分别为220 GHz和48 GHz.据我们所知,该f_T值是目前国内InAlN/GaN HFETs器件报道的最高结果.     

SiC衬底上栅长70 nm fT / fmax >160 GHz的InAlN/GaN HEMTs器件

在SiC衬底上制备了InAlN/GaN 高电子迁移率晶体管（HEMTs）,并进行了表征。为提高器件性能,综合采用了多种技术,包括高电子浓度,70 nm T型栅,小的欧姆接触电阻和小源漏间距。制备的InAlN/GaN器件在栅偏压为1 V时得到的最大饱和漏电流密度为1.65 A/mm,最大峰值跨导为382 mS/mm。70 nm栅长器件的电流增益截止频率fT和最大振荡频率fmax分别为162 GHz和176 GHz。     

基于MOCVD再生长n_+ GaN欧姆接触工艺f_T/f_(max)>150/210 GHz的AlGaN/GaN HFETs器件研究（英文）

基于SiC衬底AlGaN/GaN异质结材料研制具有高电流增益截止频率(fT)和最大振荡频率(fmax)的AlGaN/GaN异质结场效应晶体管(HFETs).基于MOCVD外延n+GaN欧姆接触工艺实现了器件尺寸的缩小,有效源漏间距(Lsd)缩小至600 nm.此外,采用自对准工艺制备了60 nm T型栅.由于器件尺寸的缩小,在Vgs=2 V下,器件最大饱和电流(Ids)达到2.0 A/mm,该值为AlGaN/GaN HFETs器件直流测试下的最高值,器件峰值跨导达到608 mS/mm.小信号测试表明,器件fT和fmax最高值分别达到152 GHz和219 GHz.     

基于MOCVD再生长n+ GaN 欧姆接触工艺fT/fmax＞150/210 GHz的AlGaN/GaN HFETs器件研究

基于SiC衬底AlGaN/GaN异质结材料研制具有高电流增益截止频率(fT)和最大振荡频率(fmax)的AlGaN/GaN异质结场效应晶体管(HFETs).基于MOCVD外延n+ GaN 欧姆接触工艺实现了器件尺寸的缩小, 有效源漏间距(Lsd)缩小至600 nm.此外, 采用自对准工艺制备了60 nm T型栅.由于器件尺寸的缩小, 在Vgs=2 V下, 器件最大饱和电流(Ids)达到2.0 A/mm, 该值为AlGaN/GaN HFETs器件直流测试下的最高值, 器件峰值跨导达到608 mS/mm.小信号测试表明, 器件fT和fmax最高值分别达到152 GHz和219 GHz.     

fT为102 GHz的蓝宝石衬底AlGaN/GaN高电子迁移率晶体管

研究了一款高性能的AlGaN/GaN高电子迁移率晶体管器件(HEMT),器件基于在蓝宝石衬底上外延生长的AlGaN/GaN异质结构HEMT材料,器件栅长为86 nm,源漏间距为0.8μm。电子束光刻实现T型栅和源漏,保证了器件小的栅长和高的对准精度。制备的器件显示了良好的直流特性和射频特性,在栅偏压为0 V时漏电流密度为995 mA/mm,在栅源电压Vgs为-4.5 V时,最大峰值跨导为225 mS/mm;器件的电流增益截止频率fT和最大振荡频率fmax分别为102和147 GHz。高fT值一方面得益于小栅长,另一方面由于小源漏间距减小了源漏沟道电阻。     

低导通电阻和栅漏电的高性能InAlN/GaN HEMT

本文制备了100nm栅长的InAlN/GaN HEMT。通过氧处理和优化欧姆接触获得了高性能的InAlN/GaN HEMT。所制备的器件在栅压偏置为2V时,漏端输出电流密度达到2.18A/mm。器件的导通电阻为1.49Ω*mm。与常规器件相比,器件的栅漏电下降了两个数量级。器件也获得良好的射频特性,电流截止频率和最高震荡频率分别为81GHz和138GHz。根据现有的报道,这是国内较早报道GaN基HEMT电流密度超过2A/mm。     

An Al0.3Ga0.7N/GaN undoped channelheterostructure field effect transistor with Fmax of 107 GHz

An Al_0.3Ga_0.7N/GaN heterostructure field effect transistor (HFET) grown on semi-insulating SiC with an 0.2-μm gate length is reported. A source-drain ohmic contact resistance of 0.15-Ω-mm was achieved through the use of high Al content and high n-type doping (1E19 cm^-3) in the AlGaN donor layer and optimized metallization procedures. We obtained a maximum transconductance of 260 mS/mm, a saturated current density of 1.2 A/mm, and a maximum oscillation frequency in excess of 107 GHz in the devices. The results are one of the best achieved up to now, and they will open up the potential for the applications of AlGaN/GaN HFET's in high-power microwave radar, remote sensing, and communications     

Nonalloyed ohmic contacts in AlGaN/GaN HEMTs by ion implantation with reduced activation annealing temperature

This letter reports AlGaN/GaN high-electron mobility transistors with capless activation annealing of implanted Si for nonalloyed ohmic contacts. Source and drain areas were implanted with an Si dose of 1/spl times/10/sup 16/ cm/sup -2/ and were activated at /spl sim/1260/spl deg/C in a metal-organic chemical vapor deposition system in ammonia and nitrogen at atmospheric pressure. Nonalloyed ohmic contacts to ion-implanted devices showed a contact resistance of 0.96 /spl Omega//spl middot/mm to the channel. An output power density of 5 W/mm was measured at 4 GHz, with 58% power-added efficiency and a gain of 11.7 dB at a drain bias of 30 V.     

Delta-doped AlGaN/AlN/GaN microwave HFETs grown by metalorganicchemical vapour deposition

The performance of an innovative delta-doped AlGaN/AlN/GaN heterojunction field-effect transistor (HFET) structure is reported. The epitaxial heterostructures were grown on semi-insulating SiC substrates by low-pressure metalorganic chemical vapour deposition. These structures exhibit a maximum carrier mobility of 1058 cm²/V s and a sheet carrier density of 2.35×10¹³ cm^-2 at room temperature, corresponding to a large n_s μ_n product of 2.49×10¹⁶ V s. HFET devices with 0.25 μm gate length were fabricated and exhibited a maximum current density as high as 1.5 A/mm (at V_G=+1 V) and a peak transconductance of g_m=240 mS/mm. High-frequency device measurements yielded a cutoff frequency of f_t≃50 GHz and maximum oscillation frequency f_max≃130 GHz     

High-Temperature Operation of AlGaN/GaN HFET With a Low on-State Resistance, High Breakdown Voltage, and Fast Switching

Improved characteristics of an AlGaN/GaN HFET are reported. In this paper, the authors introduce a new ohmic electrode of Ti/AlSi/Mo and a low refractive index SiN_x to decrease the contact resistance and gate leakage current. The AlGaN/GaN HFET showed a low specific resistance of 6.3 mOmega middot cm² and a high breakdown voltage of 750 V. The switching characteristics of an AlGaN/GaN HFET are investigated. The small turn-on delay of 7.2 ns, which was one-tenth of Si MOSFETs, was measured. The switching operation of the HFET showed no significant degradation up to 225 degC     

AlGaN/GaN metal oxide semiconductor heterostructure field effecttransistor

We report on the AlGaN/GaN metal oxide semiconductor heterostructure field effect transistor (MOS-HFET) and present the results of the comparative studies of this device and a base line AlGaN/GaN heterostructure field effect transistor (HFET). For a 5-μ source-to-drain opening, the maximum current was close to 600 mA/mm for both devices. The gate leakage current for the MOS-HFET was more than six orders of magnitude smaller than for the HFET     

AlGaN/GaN异质结构欧姆接触的研制

研究了 Ga N高温宽禁带半导体外延层上欧姆接触的制备工艺 ,讨论了几种测试方法的优缺点 ,并根据器件制作的工艺兼容性 ,在 n-Ga N样品上获得了 4× 1 0 - 6 Ω·cm2的欧姆接触 ,在 Al Ga N/Ga N异质结构样品上获得了 4× 1 0 - 4Ω· cm2 的欧姆接触。实验结果表明 ,Al Ga N/Ga N上低阻欧姆接触的制备及其工艺兼容性是Ga N HFET器件研制的技术难点     

氧等离子体表面处理对AlGaN/GaN HEMT欧姆接触的影响

采用电感耦合等离子体(ICP)刻蚀系统,研究了氧等离子体表面处理对AlGaN/GaN HEMT欧姆接触电阻的影响。利用能量色散X射线光谱仪、光致发光谱和原子力显微镜以及电学测试设备对处理前后样品进行表征分析。结果表明,在最佳的氧等离子体处理条件(ICP功率250 W,射频功率60 W,压强0.8 Pa,氧气流量30 cm³/min,时间5 min)下,欧姆接触电阻为0.41Ω·mm,比参照样品接触电阻降低了约69%。分析认为经过氧等离子体处理后,在近表面处产生了一定数量的N空位缺陷,这些N空位表现为浅能级施主掺杂,有利于欧姆接触的形成。通过采用氧等离子体表面处理工艺制备的AlGaN/GaN HEMT,在+2 V的栅极偏压下获得了0.77 A/mm的最大漏极饱和电流。     

蓝宝石衬底AlGaNöGaN 功率HEM Ts 研制

基于蓝宝石衬底的高微波特性 Al Ga N/Ga N HEMTs功率器件 ,器件采用了新的欧姆接触和新型空气桥方案。测试表明 ,器件电流密度 0 .784A/mm,跨导 1 97m S/mm,关态击穿电压 >80 V,截止态漏电很小 ,栅宽 1 mm的器件的单位截止频率 ( f T)达到 2 0 GHz,最大振荡频率 ( fmax) 2 8GHz,2 GHz脉冲测试下 ,栅宽 0 .75 mm器件 ,功率增益1 1 .8d B,输出功率 3 1 .2 d Bm,功率密度 1 .75 W/mm。