GaAs基单片集成InGaP/AlGaAs/InGaAs增强/耗尽型PHEMTs

提出了一种新结构单片集成增强/耗尽型(E/D)InGaP/AlGaAs/InGaAs赝配高电子迁移率晶体管(PHEMTs).外延层材料通过分子束外延技术生长,在室温下,其电子迁移率和二维电子气浓度分别为5410cm2/(V·s)和1.34×1012cm-2.首次提出了普通光学接触曝光分步制作增强与耗尽型的栅技术方法.研制出了单片集成E/D型PHEMTs,获得良好的直流和交流特性,最大饱和漏电流密度分别为300和340mA/mm,跨导为350和300mS/mm,阈值电压为0.2和-0.4V,增强型的fT和fmax为10.3和12.4GHz,耗尽型的fT和fmax为12.8和14.7GHz.增强/耗尽型PHEMTs的栅漏反向击穿电压都为-14V.     

Monolithic Integration of InGaP/AlGaAs/InGaAs Enhancement/Depletion-Mode PHEMTs

提出了一种新结构单片集成增强/耗尽型(E/D)InGaP/AlGaAs/InGaAs赝配高电子迁移率晶体管(PHEMTs).外延层材料通过分子束外延技术生长,在室温下,其电子迁移率和二维电子气浓度分别为5410cm2/(V·s)和1.34×1012cm-2.首次提出了普通光学接触曝光分步制作增强与耗尽型的栅技术方法.研制出了单片集成E/D型PHEMTs,获得良好的直流和交流特性,最大饱和漏电流密度分别为300和340mA/mm,跨导为350和300mS/mm,阈值电压为0.2和-0.4V,增强型的fT和fmax为10.3和12.4GHz,耗尽型的fT和fmax为12.8和14.7GHz.增强/耗尽型PHEMTs的栅漏反向击穿电压都为-14V.     

单片集成0.8μm栅长GaAs基InGaP/AlGaAs/InGaAs增强/耗尽型赝配高电子迁移率晶体管

优化了GaAs基InGaP/AlGaAs/InGaAs赝配高电子迁移率晶体管(PHEMT)的外延结构,有利于获得增强型PHEMT的正向阈值电压.采用光学接触式光刻方式,实现了单片集成0.8μm栅长GaAs基InGaP/AlGaAs/InGaAs增强/耗尽型PHEMT.直流和高频测试结果显示:增强型(耗尽型)PHEMT的阈值电压、非本征跨导、最大饱和漏电流密度、电流增益截止频率、最高振荡频率分别为0.1V(-0.5V),330mS/mm(260mS/mm),245mA/mm(255mA/mm),14.9GHz(14.5GHz)和18GHz(20GHz).利用单片集成增强/耗尽型PHEMT实现了直接耦合场效应晶体管逻辑反相器,电源电压为1V,输入0.15V电压时,输出电压为0.98V;输入0.3V电压时,输出电压为0.18V.     

单片集成0.8μm栅长GaAs基InGaP/AlGaAs/InGaAs增强/耗尽型赝配高电子迁移率晶体管

优化了GaAs基InGaP/AlGaAs/InGaAs赝配高电子迁移率晶体管(PHEMT)的外延结构,有利于获得增强型PHEMT的正向阈值电压.采用光学接触式光刻方式,实现了单片集成0.8μm栅长GaAs基InGaP/AlGaAs/InGaAs增强/耗尽型PHEMT.直流和高频测试结果显示:增强型(耗尽型)PHEMT的阈值电压、非本征跨导、最大饱和漏电流密度、电流增益截止频率、最高振荡频率分别为0.1V(-0.5V),330mS/mm(260mS/mm),245mA/mm(255mA/mm),14.9GHz(14.5GHz)和18GHz(20GHz).利用单片集成增强/耗尽型PHEMT实现了直接耦合场效应晶体管逻辑反相器,电源电压为1V,输入0.15V电压时,输出电压为0.98V;输入0.3V电压时,输出电压为0.18V.     

最大振荡频率640 GHz的70 nm栅长InAs PHEMTs器件

由于高的电子迁移率和二维电子气浓度,InP基赝配高电子迁移率晶体管（PHEMTs）器件成为制作太赫兹器件最有前途的三端器件之一。为提高器件的工作频率,采用InAs复合沟道,使得二维电子气的电子迁移率达到13000 cm2/（Vs）。成功研制出70 nm栅长的InP基赝配高电子迁移率晶体管,器件采用双指,总栅宽为30 m,源漏间距为2 m。为降低器件的寄生电容,设计T型栅的栅根高度达到210 nm。器件的最大漏端电流为1440 mA/mm （VGS=0.4 V）,最大峰值跨导为2230 mS/mm。截止频率fT和最大振荡频率fmax分别为280 GHz和640 GHz。这些性能显示该器件适于毫米波和太赫兹波应用。     

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。     

1.0μm栅长GaAs基MHEMT器件及SPDT开关MMIC

利用MBE外延材料和接触式光学光刻方式,成功制备出1.0μm栅长GaAs基MHEMT器件,分别蒸发Pt/Ti/Pt/Au和Ti/Pt/Au作为栅电极金属.获得了优越的DC和RF性能,Pt/Ti/Pt/Au和Ti/Pt/Au MHEMT器件的gm为502(503)mS/mm,JDss为382(530)mA/mm,VT为0.1(-0.5)V,fT和fmax分别为13.4(14.8),17.0(17.5)GHz.利用单片集成增强/耗尽型GaAs基MHEMT器件制备出九阶环型振荡器,直流电压为1.2V时,振荡频率达到777.6MHz,门延迟时间为71.4ps.利用Ti/Pt/Au MHEMT器件设计并制备出了DC-100Hz单刀双掷(SPDT)关MMIC,其插入损耗、隔离度、输入输出回波损耗分别优于2.93,23.34和20dB.     

1.0μm栅长GaAs基MHEMT器件及SPDT开关MMIC

利用MBE外延材料和接触式光学光刻方式,成功制备出1.0μm栅长GaAs基MHEMT器件,分别蒸发Pt/Ti/Pt/Au和Ti/Pt/Au作为栅电极金属.获得了优越的DC和RF性能,Pt/Ti/Pt/Au和Ti/Pt/Au MHEMT器件的gm为502(503)mS/mm,JDss为382(530)mA/mm,VT为0.1(-0.5)V,fT和fmax分别为13.4(14.8),17.0(17.5)GHz.利用单片集成增强/耗尽型GaAs基MHEMT器件制备出九阶环型振荡器,直流电压为1.2V时,振荡频率达到777.6MHz,门延迟时间为71.4ps.利用Ti/Pt/Au MHEMT器件设计并制备出了DC-100Hz单刀双掷(SPDT)关MMIC,其插入损耗、隔离度、输入输出回波损耗分别优于2.93,23.34和20dB.     

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。     

最大振荡频率为200 GHz的蓝宝石衬底AlGaN/GaN HEMT

本文报道了fmax为200GHz的基于蓝宝石衬底的AlGaN/GaN 高电子迁移率晶体管（HEMT）。外延材料结构采用了InGaN背势垒层来减小短沟道效应,器件采用了凹栅槽和T型栅结合的工艺,实现了Ka波段AlGaN/GaN HEMT。器件饱和电流达到1.1A/mm,跨导为421mS/mm,截止频率（fT）为30GHz,最大振荡频率（fmax）为105GHz。采用了湿法腐蚀工艺将器件的Si3N4钝化层去除后,器件的Cgs和Cgd减小,器件截止频率提高到50GHz,最大振荡频率提高到200GHz。     

Morphological and electrical characterization of SixCryCzBv thin films

Si_xCr_yC_zB_v thin films with several compositions have been studied for integration of high precision resistors in 0.8 μm BICMOS technology. These resistors, integrated in the back-end of line, have the advantage to provide high level of integration and attractive electrical behavior in temperature, for analog devices. The film morphology and the structure have been investigated through transmission electron microscopy analysis and have been then related to the electrical properties on the base of the percolation theory. According to this theory, and in agreement with experimental results, negative thermal coefficient of resistance (TCR) has been obtained for samples with low Cr content, corresponding to a crystalline volume fraction below the percolation threshold.Samples with higher Cr content exhibit, instead, a variation of the TCR as a function of film thickness: negative TCR values are obtained for thickness lower than 5 nm, corresponding to a crystalline volume fraction below the percolation threshold; positive TCR are obtained for larger thickness, indicating the establishment of a continuous conductive path between the Cr rich grains. This property seems to be determinant in order to assure the possibility to obtain thin film resistors almost independent on the temperature.     

Performance improvement in tensile-strained In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As metamorphic HEMT

This paper proposes a In/sub 0.5/Al/sub 0.5/As/In/sub x/Ga/sub 1-x/As/In/sub 0.5/Al/sub 0.5/As (x=0.3-0.5-0.3) metamorphic high-electron mobility transistor with tensile-strained channel. The tensile-strained channel structure exhibits significant improvements in dc and RF characteristics, including extrinsic transconductance, current driving capability, thermal stability, unity-gain cutoff frequency, maximum oscillation frequency, output power, power gain, and power added efficiency.     

Comparison between Pt/TiO2/Pt and Pt/TaOX/TaOY/Pt based bipolar resistive switching devices

Nonvolatile memories have emerged in recent years and have become a leading candidate towards replacing dynamic and static random-access memory devices. In this article, the performances of TiO₂ and TaO₂ nonvolatile memristive devices were compared and the factors that make TaO₂ memristive devices better than TiO₂ memristive devices were studied. TaO₂ memristive devices have shown better endurance performances (10⁸ times more switching cycles) and faster switching speed (5 times) than TiO₂ memristive devices. Electroforming of TaO₂ memristive devices requires~4.5 times less energy than TiO₂ memristive devices of a similar size. The retention period of TaO₂ memristive devices is expected to exceed 10 years with sufficient experimental evidence. In addition to comparing device performances, this article also explains the differences in physical device structure, switching mechanism, and resistance switching performances of TiO₂ and TaO₂ memristive devices. This article summarizes the reasons that give TaO₂ memristive devices the advantage over TiO₂ memristive devices, in terms of electroformation, switching speed, and endurance.     

Very low-noise Al/sub 0.3/Ga/sub 0.7/As/Ga/sub 0.65/In/sub 0.35/As/GaAs single quantum-well pseudomorphic HEMTs

AlGaAs/GaInAs/GaAs pseudomorphic HEMTs with an InAs mole fraction as high as 35% in the channel has been successfully fabricated. The device exhibits a maximum extrinsic transconductance of 700 mS/mm. At 18 GHz, a minimum noise figure of 0.55 dB with 15.0 dB associated gain was measured. At 60 GHz, a minimum noise figure as low as 1.6 dB with 7.6 dB associated gain was also obtained. This is the best noise performance yet reported for GaAs-based HEMTs.<>     

A 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode array

We report a 12 /spl times/ 12 In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode (APD) array. The mean breakdown voltage of the APD was 57.9 V and the standard deviation was less than 0.1 V. The mean dark current was /spl sim/2 and /spl sim/300 nA, and the standard deviation was /spl sim/0.19 and /spl sim/60 nA at unity gain (V/sub bias/ = 13.5 V) and at 90% of the breakdown voltage, respectively. External quantum efficiency was above 40% in the wavelength range from 1.0 to 1.6 /spl mu/m. It was /spl sim/57% and /spl sim/45% at 1.3 and 1.55 /spl mu/m, respectively. A bandwidth of 13 GHz was achieved at low gain.     

Lanthanum diffusion in the TiN/LaOx/HfSiO/SiO2/Si stack

Band edge Complementary Metal Oxide Semiconductor (CMOS) devices are obtained by insertion of a thin LaO_x layer between the high-k (HfSiO) and metal gate (TiN). High temperature post deposition anneal induces Lanthanum diffusion across the HfSiO towards the SiO₂ interfacial layer, as shown by Time of Flight Secondary Ions Mass Spectroscopy (ToF-SIMS) and Atom Probe Tomography (APT). Fourier Transform Infrared Spectroscopy in Attenuated Total Reflexion mode (ATR-FTIR) shows the formation of La-O-Si bonds at the high-k/SiO₂ interface. Soft X-ray Photoelectron Spectroscopy (S-XPS) is performed after partial removal of the TiN gate. Results confirm La diffusion and changes in the La chemical environment.     

The C-V-f and G/ω-V-f characteristics of Al/SiO2/p-Si (MIS) structures

The frequency dependence of capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the Al/SiO₂/p-Si metal-insulator-semiconductor (MIS) structures has been investigated taking into account the effect of the series resistance (R_s) and interface states (N_ss) at room temperature. The C-V and G/ω-V measurements have been carried out in the frequency range of 1 kHz to 1 MHz. The frequency dispersion in capacitance and conductance can be interpreted only in terms of interface states and series resistance. The N_ss can follow the ac signal and yield an excess capacitance especially at low frequencies. In low frequencies, the values of measured C and G/ω decrease in depletion and accumulation regions with increasing frequencies due to a continuous density distribution of interface states. The C-V plots exhibit anomalous peaks due to the N_ss and R_s effect. It has been experimentally determined that the peak positions in the C-V plot shift towards lower voltages and the peak value of the capacitance decreases with increasing frequency. The effect of series resistance on the capacitance is found appreciable at higher frequencies due to the interface state capacitance decreasing with increasing frequency. In addition, the high-frequency capacitance (C_m) and conductance (G_m/ω) values measured under both reverse and forward bias were corrected for the effect of series resistance to obtain the real diode capacitance. Experimental results show that the locations of N_ss and R_s have a significant effect on electrical characteristics of MIS structures.     

Highly linear Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMTs

We report an Al/sub 0.3/Ga/sub 0.7/N-Al/sub 0.05/Ga/sub 0.95/N-GaN composite-channel HEMT with enhanced linearity. By engineering the channel region, i.e., inserting a 6-nm-thick AlGaN layer with 5% Al composition in the channel region, a composite-channel HEMT was demonstrated. Transconductance and cutoff frequencies of a 1 /spl times/100 /spl mu/m HEMT are kept near their peak values throughout the low- and high-current operating levels, a desirable feature for linear power amplifiers. The composite-channel HEMT exhibits a peak transconductance of 150 mS/mm, a peak current gain cutoff frequency (f/sub T/) of 12 GHz and a peak power gain cutoff frequency (f/sub max/) of 30 GHz. For devices grown on sapphire substrate, maximum power density of 3.38 W/mm, power-added efficiency of 45% are obtained at 2 GHz. The output third-order intercept point (OIP3) is 33.2 dBm from two-tone measurement at 2 GHz.     

Al/sub 0.3/Ga/sub 0.7/As/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) doped-channel field-effect transistors (DCFET's)

The properties of both lattice-matched and strained doped-channel field-effect transistors (DCFET's) have been investigated in AlGaAs/In/sub x/Ga/sub 1-x/As (0/spl les/x/spl les/0.25) heterostructures with various indium mole fractions. Through electrical characterization of grown layers in conjunction with the dc and microwave device characteristics, we observed that the introduction of a 150-/spl Aring/ thick strained In/sub 0.15/Ga/sub 0.85/As channel can enhance device performance, compared to the lattice-matched one. However, a degradation of device performance was observed for larger indium mole fractions, up to x=0.25, which is associated with strain relaxation in this highly strained channel. DCFET's also preserved a more reliable performance after biased-stress testings.<>