太赫兹InP基InAlAs/InGaAs PHEMTs的研制

研制了一种T型栅长为90 nm的InP基In0.52Al0.48As/In0.65Ga0.35As赝配高电子迁移率晶体管(PHEMTs).该器件的总栅宽为2×25 μm,展现了极好的DC直流和RF射频特性,其最大饱和电流密度和最大有效跨导分别为894 mA/mm和1640 mS/mm.采用LRM+ (Line-Reflect-Reflect -Match)校准方法实现系统在1~110 GHz全频段内一次性校准,减小了传统的分段测试多次校准带来的误差, 且测试数据的连续性较好.在国内完成了器件的1~110 GHz全频段在片测试,基于1~110 GHz在片测试的S参数外推获得的截止频率ft和最大振荡频率fmax分别为252 GHz和394 GHz.与传统的测试到40 GHz外推相比,本文外推获得的fmax更加准确.这些结果的获得是由于栅长的缩短,寄生效应的减小以及1~110 GHz全频段在片测试的实现.器件的欧姆接触电阻率减小为0.035 Ω·mm.     

基于70nm GaAs MHEMT工艺的W波段低噪声放大器

报道了一种采用电子束直写70nm"Y"型栅工艺制备的GaAs MHEMT器件及W波段低噪声放大器。器件的最大跨导可达到1 050mS/mm,最大电流密度可达650mA/mm。通过小信号S参数测试,可外推其电流增益截至频率fT及最大振荡频率fmax分别达350GHz及470GHz。采用该工艺制备的W波段低噪声放大器,在86~96GHz频段可实现噪声系数小于3dB,增益大于20dB。     

太赫兹InP基InAlAs/InGaAs PHEMTs的研制（英文）

研制了一种T型栅长为90 nm的InP基In_(0.52)Al_(0.48)As/In_(0.65)Ga_(0.35)As赝配高电子迁移率晶体管(PHEMTs).该器件的总栅宽为2×25μm,展现了极好的DC直流和RF射频特性,其最大饱和电流密度和最大有效跨导分别为894 m A/mm和1 640 m S/mm.采用LRM+(Line-Reflect-Reflect-Match)校准方法实现系统在1~110 GHz全频段内一次性校准,减小了传统的分段测试多次校准带来的误差,且测试数据的连续性较好.在国内完成了器件的1~110 GHz全频段在片测试,基于1~110 GHz在片测试的S参数外推获得的截止频率ft和最大振荡频率f_(max)分别为252 GHz和394 GHz.与传统的测试到40 GHz外推相比,本文外推获得的f_(max)更加准确.这些结果的获得是由于栅长的缩短,寄生效应的减小以及1~110 GHz全频段在片测试的实现.器件的欧姆接触电阻率减小为0.035Ω·mm.     

基于AlN/GaN异质结的Ka波段GaN低噪声放大器研制

报道了基于AlN/GaN异质结的Ka波段低噪声放大器的研制结果。在SiC衬底上生长AlN/GaN异质结材料结构,采用电子束直写工艺制备了栅长70 nm的"T"型栅结构。器件最大电流密度为1.50 A/mm,最大跨导为650 mS/mm,通过S参数测试外推特征频率和最大频率分别为105 GHz和235 GHz。基于70 nm工艺制备的自偏压三级低噪声放大器,在33~40 GHz小信号增益大于27 dB,典型噪声系数为1.5 dB。     

电子束实现210 nm栅长115 GHz GaAs基mHEMT器件

为了获得T型栅应变高电子迁移率晶体管(mHEMT)器件,利用电子束(Electron beam,E-beam)光刻技术制备了210 nm栅长,减小mHEMT器件栅极的寄生电容和寄生电阻。采用PMMA A4/ PMMA-MMA/PMMA A2三层胶电子束直写的方法定义了210 nm栅长T型栅极。InAlAs/ InGaAs异质结GaAs-mHEMT器件的直流特性和高频特性分别通过Agilent B1500半导体参数分析仪和Agilent 360 B矢量网络分析仪测试。直流测试结果显示,210 nm栅长InAlAs/InGaAs沟道GaAs-mHEMT单指器件的最大有效输出跨导(gm:max)为195 mS/mm,器件最大沟道电流160 mA/mm。射频测试结果显示,电流增益截至频率(fT)和最高振荡频率(fmax)分别为46 GHz和115 GHz。同时欧姆电极特性和栅极漏电特性也被表征,其中栅极最大饱和漏电流密度小于1×10-8 A/μm。     

具有136GHz的0.18m GaAs Metamorphic HEMT器件

应用电子束直写技术成功制作了栅长0.18μm的高性能In0.52Al0.48As/In0.53Ga0.47As MHEMT。从工艺角度,结合器件的小信号等效电路的理论分析,优化了器件结构,特别是T形栅结构,从而减小了器件寄生参数,达到了较好的器件性能。最终制作的In0.52Al0.48As/In0.53Ga0.47As MHEMT饱和电流达到275mA/mm,夹断电压-0.8V,在Vgs为-0.15V时的最大非本征跨导gm为650mS/mm,截止频率ft达到136GHz,最大振荡频率fmax大于120GHz。     

Ka波段GaN单片低噪声放大器研制

报道了Ka波段GaN自偏压低噪声三级放大电路的研制结果。在高Al含量的AlGaN/GaN HEMT外延结构上,采用电子束直写工艺制备了栅长100nm的"T"型栅结构。器件直流测试最大电流密度为1.55A/mm,最大跨导为490mS/mm;小信号测试外推其fT和fmax分别为95GHz及230GHz。采用该工艺制备的自偏压三级放大电路工作电压7V,在33~47GHz小信号增益大于20dB,噪声系数均值在2dB左右,单频点噪声系数可达1.6dB,噪声水平达到GaN器件在该频段的高水平。此外,该单片电路的功耗在560mW左右,带内连续波测试输出P-1>15dBm。     

具有136 GHz的0.18μm GaAs Metamorphic HEMT器件

应用电子束直写技术成功制作了栅长0.18μm的高性能In0.52Al0.48As/In0.53Ga0.47As MHEMT.从工艺角度,结合器件的小信号等效电路的理论分析,优化了器件结构,特别是T形栅结构.从而减小了器件寄生参数,达到了较好的器件性能.最终制作的In0.52Al0.48As/In0.53Ga0.47As MHEMT饱和电流达到275 mA/mm,夹断电压-0.8 V,在Uga为-0.15 V时的最大非本征跨导gm为650 mS/mm,截止频率ft达到136 GHz,最大振荡频率fmax大于120 GHz.     

100nm GaAs MHEMT器件研制

应用电子束直写技术成功制作了栅长100nm的高性能In0.52Al0.48As/In0.53Ga0.47As GaAs MHEMT(渐变组分高电子迁移率晶体管)。从工艺角度,结合器件的小信号等效电路的理论分析,优化了器件T形栅尺寸与工艺,从而减小了器件寄生参数,达到了较好的器件性能。最终制作的In0.52Al0.48As/In0.53Ga0.47As MHEMT饱和电流达到460mA/mm,夹断电压-0.8V,在Vgs为-0.23V时的最大非本征跨导gm为940mS/mm,截止频率ft达到220GHz,最大振荡频率fmax大于200GHz。     

W波段GaN单片功率放大器研制

报道了W波段GaN三级放大电路的研制结果。采用电子束直写工艺在AlGaN/GaN HEMT外延结构上制备了栅长100nm的"T"型栅结构。器件直流测试最大电流密度为1.3A/mm,最大跨导为430mS/mm;小信号测试外推其fT和fmax分别为90GHz及210GHz。采用该器件设计了三级放大电路,在75~110GHz频段内最大小信号增益为21dB。该单片在90GHz处的最大输出功率可达1.117W,PAE为13%,功率增益为11dB,输出功率密度为2.33 W/mm。     

Enhanced characteristics in gate-recessed and sidewall-recessed AlGaAs/InGaAs PHEMTs by citric-based selective wet etching

Improved device performance in Al_0.2Ga_0.8As/In_0.15Ga_0.85As gate-recessed enhancement-mode pseudomorphic high electron mobility transistors (E-PHEMTs) and sidewall-recessed depletion-mode PHEMTs (D-PHEMTs) using a newly developed citric buffer etchant are reported. The innovated etchant near room temperature (23°C) possesses a high GaAs/Al_0.2Ga_0.8As or In_0.15Ga_0.85As/Al_0.2Ga_0.8As etching selectivity (>250) applied to an etched stop surface. For E-PHEMTs, the transconductance (G_m) of 315?mS/mm and high linearity of 0.46?V-wide gate voltage swing (drop of 10% peak G_m), corresponding to 143?mA/mm-wide I_DS, even at a gate length of 1?µm is obtained. For microwave operation, this 1?µm-gate E-PHEMT shows the f_max (maximum operation frequency) of 29.2?GHz and the f_T (cut-off frequency) of 11.2?GHz, respectively. The measured minimum noise figure (NF_min), under V_DS?=?3?V and I_DS?=?7.5?mA, is 0.56?dB at 1?GHz with the associated gain of 10.86?dB. The NF_min is less than 1.5?dB in the frequency range from 1 to 4?GHz. In addition, an effective and simple method of selective gate sidewall recess is utilized to etch the low barrier in In_0.15Ga_0.85As channel at mesa sidewalls for D-PHEMTs. For D-PHEMTs with 1?×?100?µm² exhibit a very low gate leakage current of 2.4?μA/mm even at V_GD?=??10?V and high gate breakdown voltage over 25?V. As compared to that of no sidewall recess, nearly two orders of reduction in magnitude of gate leakage current and 100% improvement in gate breakdown voltage are achieved.     

In0.48Ga0.52P/In0.20Ga0.80As/GaAs pseudomorphic high electron mobility transistors grown by solid-source molecular-beam epitaxy using a valved phosphorus cracker cell

In_0.48Ga_0.52P/In_0.20Ga_0.80As/GaAs pseudomorphic high electron mobility transistor (p-HEMT) structures were grown by solid-source molecular beam epitaxy (SSMBE) using a valved phosphorus cracker cell. The sheet carrier density at room temperature was 3.3 × 10¹²cm^?2. A peak transconductance (G _m) of 267 mS mm^?1 and peak drain current density (I _ds) of 360 mA mm^?1 were measured for a p-HEMT device with 1.25 µm gate length. A high gate-drain breakdown voltage (BV _gd) of 33V was measured. This value is more than doubled compared with that of a conventional Al_0.30Ga_0.70As/In_0.20Ga_0.80As/GaAs device. The drain-source breakdown voltage (BV _ds) was 12.5V. Devices with a mushroom gate of 0.25 µm gate length and 80 µm gate width achieved a peak transconductance (G _m) of 420 mS mm^?1 and drain current density of nearly 500mA mm^?1. A high cutoff frequency (f _T) of 58GHz and maximum oscillation frequency (f _max) of 120 GHz were obtained. The results showed that the In_0.48Ga_0.52P/In_0.20Ga_0.80As/GaAs material system grown by SSMBE using the valved phosphorus cracker cell for the In^0.48Ga^0.52P Schottky and spacer layers is a viable technology for high frequency p-HEMT device applications.     

Pseudomorphic AlGaAs/InGaAs/GaAs High Electron Mobility Transistors with Super Low Noise Performances of 0.41 dB at 18 GHz

Fully passivated low noise AlGaAs/InGaAs/GaAs pseudomorphic (PM) HEMT with wide head T-shaped gates were fabricated by dose split electron beam lithography (DSL). The dimensions of gate head and footprint were optimized by controlling the splitted pattern size, dose, and spaces of each pattern. We obtained stable T-shaped gate of 0.15 μm gate length with 1.35 μm-wide head. The maximum extrinsic transconductance was 560 mS/mm. The minimum noise figure measured at 18 GHz at V_ds = 2 V and I_ds = 17 mA was 0.41 dB with associated gain of 8.19 dB. At 12 GHz, the minimum noise figure and an associated gain were 0.26 and 10.25 dB, respectively. These noise figures are the lowest values ever reported for GaAs-based HEMTs. These results are attributed to the extremely low gate resistance of wide head T-shaped gate having a ratio of the head to footprint dimensions larger than 9.     

Improvement on the noise performance of InAs-based HEMTs with gate sinking technology

Improvement on the RF and noise performance for 80 nm InAs/In_0.7Ga_0.3As high-electron mobility transistor (HEMT) through gate sinking technology is presented. After gate sinking at 250 °C for 3 min, the device exhibited a high transconductance of 1900 mS/mm at a drain bias of 0.5 V with 1066 mA/mm drain-source saturation current. A current-gain cutoff frequency (f_T) of 113 GHz and a maximum oscillation frequency (f_max) of 110 GHz were achieved at extremely low drain bias of 0.1 V. The 0.08 × 40 μm² device with gate sinking demonstrated 0.82 dB minimum noise figure and 14 dB associated gain at 17 GHz with only 1.14 mW DC power consumption. Significant improvement in RF and noise performance was mainly attributed to the reduction of gate-to-channel distance together with the parasitic source resistance through gate sinking technology.     

Simulation of InGaAs subchannel DG-HEMTs for analogue/RF applications

The paper reports on the influence of a barrier thickness and gate length on the various device parameters of double gate high electron mobility transistors (DG-HEMTs). The DC and RF performance of the device have been studied by varying the barrier thickness from 1 to 5 nm and gate length from 10 to 150 nm, respectively. As the gate length is reduced below 50 nm regime, the barrier thickness plays an important role in device performance. Scaling the gate length leads to higher transconductance and high frequency operations with the expense of poor short channel effects. The authors claim that the 30-nm gate length, mole fractions tuned In_0.53Ga_0.47As/In_0.7Ga_0.3As/In_0.53Ga_0.47As subchannel DG-HEMT with optimised device structure of 2 nm In_0.48Al_0.52As barrier layer show a peak g_m of 3.09 mS/µm, V_T of 0.29 V, I_ON/I_OFF ratio of 2.24 × 10⁵, subthreshold slope ~73 mV/decade and drain induced barrier lowering ~68 mV/V with f_T and f_max of 776 and 905 GHz at V_ds = 0.5 V is achieved. These superior performances are achieved by using double-gate architecture with reduced gate to channel distance.     

Comparative assessment of InGaAs sub-channel and InAs composite channel double gate (DG)-HEMT for sub-millimeter wave applications

This work analyses the impact of channel material, channel thickness (T_CH) and gate length (L_g) on the various performance device metrics of Double-gate (DG) High Electron Mobility Transistor (HEMT) by using 2D Sentaurus TCAD simulation. A comparison between In_0.53Ga_0.47As/In_0.7Ga_0.3As/In_0.53Ga_0.47As sub-channel and In_0.7Ga_0.3As/InAs/In_0.7Ga_0.3As composite channel DG-HEMT along with SG-HEMT is made by characterizing the device with structural and geometrical parameters suitable for applications requiring high frequency operations. The DG-In_0.53Ga_0.7As/In_0.7Ga_0.3As/In_0.53Ga_0.7As sub-channel/DG-In_0.7Ga_0.3As/InAs/In_0.7Ga_0.3As composite channel HEMT with channel thickness of 13 nm and barrier thickness (T_B) of 2 nm with L_g = 30 nm are seen offering a positive threshold voltage (V_T) of 0.298/0.21 V, transconductance (g_m) of 3.09/3.3 mS/µm, with cut-off frequency (f_T) and maximum oscillation frequency (f_max) of 776/788 GHz and 905/978 GHz, respectively at V_ds = 0.5 V is obtained. If the channel thickness of the DG-InAs composite channel device is scaled and reduced to 10 nm, the RF performances are further enhanced to 809 GHz (f_T) and 1030 GHz (f_max). Compared to DG-InGaAs sub-channel device, the device with thin DG-InAs composite channel device shows a better performance in terms of drain current (I_ds), analog/RF performance thereby making it preferable for future THz applications.     

GaAs-based metal-oxide semiconductor field-effect transistors with Al2O3 gate dielectrics grown by atomic layer deposition

We demonstrate GaAs-based, metal-oxide-semiconductor field-effect transistors (MOSFETs) with excellent performance using an Al₂O₃ gate dielectric, deposited by atomic layer deposition (ALD). This achievement is very significant because Al₂O₃ possesses highly desirable physical and electrical properties as a gate dielectric. These MOSFET devices exhibit extremely low gate-leakage current, high transconductance, and high dielectric breakdown strength. A short-circuit, current-gain, cutoff frequency (f_T) of 14 GHz and a maximum oscillation frequency (f_max) of 25.2 GHz have been achieved from a 0.65-μm gate-length device. The interface trap density (D_it) of Al₂O₃/GaAs is evaluated by the hysteresis of drain-source current, I_ds, versus gate-source bias, V_gs, and the frequency dispersion of transconductance, g_m.     

基于再生长欧姆接触工艺的220 GHz InAlN/GaN 场效应晶体管

本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(L_sd)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,V_gs= 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。小信号测试表明,器件f_T达到220 GHz、最大振荡频率(f_max)达到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。     

20-nm enhancement-mode metamorphic GaAs HEMT with highly doped InGaAs source/drain regions for high-frequency applications

In this article, the DC and RF performance of a SiN passivated 20-nm gate length metamorphic high electron mobility transistor (MHEMT) on GaAs substrate with highly doped InGaAs source/drain (S/D) regions have investigated using the Synopsys TCAD tool. The 20-nm enhancement-mode (E-mode) MHEMT device also features δ-doped sheets on either side of the In_0.53Ga_0.47As/InAs/In_0.53Ga_0.47As channel which exhibits a transconductance of 3100 mS/mm, cut-off frequency (f_T) of 740 GHz and a maximum oscillation frequency (f_max) of 1040 GHz. The threshold voltage of the device is found to be 0.07 V. The room temperature Hall mobilities of the 2-dimensional sheet charge density are measured to be over 12,600 cm²/Vs with a sheet charge density larger than 3.6 × 10¹² cm^?2. These high-performance E-mode MHEMTs are attractive candidates for sub-millimetre wave applications such as high-resolution radars for space research, remote atmospheric sensing, imaging systems and also for low noise wide bandwidth amplifier for future communication systems.     

120nm栅长In0.7Ga0.3As/In0.52Al0.48As HEMTs 器件

利用新型的PMMA/PMGI/ZEP520/PMGI四层胶T形栅电子束光刻技术制备出120nm栅长InP基雁配In0.7Ga0.3As/In0.52Al0.48As 高电子迁移率晶体管。制作出的InP基HEMT器件获得了良好的直流和高频性能,跨导、饱和漏电流密度、阈值电压、电流增益截止频率和最大单向功率增益频率分别达到520 mS/mm, 446 mA/mm, -1.0 V, 141 GHz 及 120 GHz。文中的材料结构和所有器件制备均为本研究小组自主研究开发。