截止频率为218GHz的超高速晶格匹配In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管

报道了截止频率为218GHz的晶格匹配的In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管.这是迄今为止国内报道的截止频率最高的高电子迁移率晶体管.器件直流特性也很优异:跨导为980mS/mm,最大电流密度为870mA/mm.文中的材料结构和所有器件制备工艺均为本研究小组自主研制开发.     

功率增益截止频率为183GHz的In0.53Ga0.47As/In0.52Al0.48As HEMTs

通过合理的外延层材料结构设计和改进的器件制备工艺,制备出功率增益截止频率(fmax)为183GHz的晶格匹配InP基In0.53Ga0.47As-In0.52Al0.48As HEMT.该fmax为国内HEMT器件最高值.还报道了器件的结构、制备工艺以及器件的直流和高频特性.     

功率增益截止频率为183GHz的In0.53Ga0.47As/In0.52Al0.48As HEMTs

通过合理的外延层材料结构设计和改进的器件制备工艺,制备出功率增益截止频率（fmax）为183GHz的晶格匹配InP基In0.53Ga0.47As-In0.52Al0.48As HEMT。该fmax为国内HEMT器件最高值,还报道了器件的结构、制备工艺以及器件的直流和高频特性。     

Super-flat interfaces in In0.53Ga0.47As/In0.52Al0.48As quantum wells grown on (411)A InP substrates by molecular beam epitaxy

Effectively atomically flat interfaces over a macroscopic area (“(411)A super-flat interfaces”) were successfully achieved in In_0.53Ga_0.47As/In_0.52Al_0.48As quantum wells (QWs) grown on (411)A InP substrates by molecular beam epitaxy (MBE) at a substrate temperature of 570°C and V/III=6. Surface morphology of the In_0.53Ga_0.47As/In_0.52Al_0.48As QWs was smooth and featureless, while a rough surface of those simultaneously grown on a (100) InP substrate was observed. Photoluminescence (PL) linewidths at 4.2 K from the (411)A QWs with well width of 0.6–12 nm were 20–30 % narrower than those grown on a (100) InP substrate and also they are almost as narrow as each of split PL peaks for those of growth-interrupted QWs on a (100) InP substrate. In the case of the (411)A QWs, only one PL peak with very narrow linewidth was observed from each QW over a large distance (7 mm) on a wafer.     

截止频率为218GHz的超高速晶格匹配In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管

报道了截止频率为218GHz的晶格匹配的In0.53Ga0.47As/In0.52Al0.48As高电子迁移率晶体管,这是迄今为止国内报道的截止频率最高的高电子迁移率晶体管,器件直流特性也很优异：跨导为980mS/mm,最大电流密度为870mA/mm,文中的材料结构和所有器件制备工艺均为本研究小组自主研制开发。     

Photoluminescence and raman scattering characterization of silicon-doped In0.52Al0.48As grown on InP (100) substrates by molecular beam epitaxy

Growth of In_0.52Al_0.48As epilayers on InP (100) substrates by molecular beam epitaxy at different silicon doping levels is carried out. The doped samples show an inverted S-shaped dependence of the PL peak energy variation with the temperature which weakens at high doping levels due to a possible reduction in the donor binding energy. There is a reduction in both the AlAs-like and InAs-like longitudinal-optic (LO) phonon frequencies and a broadening of the LO phonon line shape as the doping level is increased. The PL intensity also showed in increasing degrees at higher doping levels, a temperature dependence which is characteristic of disordered and amorphous materials.     

有效跨导为1052 mS/mm的高性能InP基In0.52Al0.48As/In0.53Ga0.47As HEMTs

我们成功研制了栅长为0.15 μm、栅宽为2?50 μm、源漏间距为2 μm 的InP 基In_0.52Al_0.48As/In_0.53Ga_0.47As高电子迁移率器件。室温下,当器件V_DS为1.7 V,V_GS为0.1 V时,其有效跨导达到了1052 mS/mm。传输线方法(TLM)测试显示器件的接触电阻为0.032 Ω.mm,器件欧姆接触电阻率为1.03?10_-7Ω.cm_-2. 正是良好的欧姆接触及其短的源漏间距减小了源电阻,进而使得有效跨导比较大。器件还有比较好的射频特性：当V_DS＝1.5 V, V_GS ＝0.1 V 时,f_T和f_max分别为151 GHz,303 GHz。文章报道的HEMT器件非常适合毫米波段集成电路的研制。     

非对称In0.53Ga0.47As/In0.52Al0.48As量子阱的零场自旋分裂能与高场g因子

我们研究了非对称In_0.53Ga_0.47As/In_0.52Al_0.48As量子阱中二维电子气的磁输运性质,所测量的样品的径向磁阻Rxx的Shubinikov-de Haas振荡没有呈现出拍频的特征。通过测量样品的弱局域效应提取了其零场自旋分裂能并通过对自旋分裂的Rxx双峰间距随倾斜角度theta的依赖关系的拟合提取了高场下的有效g因子。样品的Dingle plot图呈现非线性和特征,这可以归因于来自样品衬底附近的掺杂Be原子的长程势散射效应。     

Persistent photoconductivity and electron mobility in In0.52Al0.48As/In0.53Ga0.47As/In0.52Al0.48As/InP quantum-well structures

The influence of the width of the quantum well L and doping on the band structure, scattering, and electron mobility in nanoheterostructures with an isomorphic In_0.52Al_0.48As/In_0.53Ga_0.47As/In_0.52Al_0.48As quantum well grown on an InP substrate are investigated. The quantum and transport mobilities of electrons in the dimensionally quantized subbands are determined using Shubnikov-de Haas effect measurements. These mobilities are also calculated for the case of ionized-impurity scattering taking into account intersub-band electron transitions. It is shown that ionized-impurity scattering is the dominant mechanism of electron scattering. At temperatures T < 170 K, persistent photoconductivity is observed, which is explained by the spatial separation of photoexcited charge carriers.     

120-nm gate-length In0.7Ga0.3As/In0.52Al0.48As InP-based HEMT

120 nm gate-length In_(0.7)Ga_(0.3)As/In_(0.52)Al_(0.48) As InP-based high electron mobility transitions(HEMTs) are fabricated by a new T-shaped gate electron beam lithograph(EBL) technology,which is achieved by the use of a PMMA/PMGI/ZEP520/PMGI four-layer photoresistor stack.These devices also demonstrate excellent DC and RF characteristics:the transconductance,maximum saturation drain-to-source current,threshold voltage,maximum current gain frequency,and maximum power-gain cutoff frequency of InGaAs/I...     

In0.53Ga0.47As/In0.52Al0.48As量子阱二维电子气中的零场自旋分裂与塞曼分裂

利用变角度磁输运方法研究了高迁移率、高浓度、宽度为20 nm、单边δ掺杂的In0.53Ga0.47As/In0.52Al0.48As量子阱,根据量子阱平面与磁场不同夹角时SdH振荡的拍频节点移动,提取了其自旋分裂能Δ0和有效g因子|g*|,发现Δ0随浓度增加而增大,|g*|随浓度增加而减小.进一步的分析和计算表明,|g*|减小是由量子阱能带结构的非抛物性作用引起的.     

Thermal characteristics of InP, InAlAs, and AlGaAsSb metamorphic buffer layers used in In0.52Al0.48As/In0.53Ga0.47As heterojunction bipolar transistors grown on GaAs substrates

In_0.52Al_0.48As/In_0.53Ga_0.47As heterojunction bipolar transistors (HBTs) were grown metamorphically on GaAs substrates by molecular beam epitaxy. In these growths, InAlAs, AlGaAsSb, and InP metamorphic buffer layers were investigated. The InAlAs and AlGaAsSb buffer layers had linear compositional grading while the InP buffer layer used direct binary deposition. The transistors grown on these three layers showed similar characteristics. Bulk thermal conductivities of 10.5, 8.4, and 16.1 W/m K were measured for the InAlAs, AlGaAsSb, and InP buffer layers, as compared to the 69 W/m K bulk thermal conductivity of bulk InP. Calculations of the resulting HBT junction temperature strongly suggest that InP metamorphic buffer layers should be employed for metamorphic HBTs operating at high power densities.     

DC and microwave characteristics of an In0.53Ga0.47As/In0.52Al0.48As modulation-doped quasi-MISFET

The DC and microwave performance of a modulation-doped InGaAs/InAlAs quasi-MISFET structure, grown by molecular beam epitaxy, is reported. Improved performance is obtained with the incorporation of Ti in the source-drain metallisation with which contact resistances as low as 0.1 ?mm are measured. An extrinsic transconductance of 310mS/mm and a best value of fT=32 GHz in a 1.0 ?-gate device are measured at 300 K.     

200nm栅长In0.52Al0.48As/In0.6Ga0.4As MHEMTs器件

利用电子束光刻技术制备出200nm栅长GaAs基InAlAs/InGaAs MHEMT器件.Ti/Pt/Au蒸发作为栅极金属.同时为了减少栅寄生电容和寄生电阻,采用3层胶工艺,实现了T型栅.GaAs基MHEMT 器件获得了优越的直流和高频性能,跨导、饱和漏电流密度、域值电压、电流增益截止频率和最大振荡频率分别达到510mS/mm,605mA/mm,-1.8V,110GHz及72GHz,为进一步研究高性能GaAs基MHEMT器件奠定了基础.     

Femtosecond optical response of low temperature grown In0.53Ga0.47As

A femtosecond, tunable color center laser was used to conduct degenerate pump-probe transmission spectroscopy of thin film low temperature grown molecular beam epitaxy In_0.53Ga_0.47As samples. Low temperature molecular beam epitaxy In_0.53Ga_0.47As exhibits a growth-temperature dependent femtosecond optical response when probed near the conduction band edge. Below T_g=250°C, the optical response time of the material is subpicosecond in duration, and we observed induced absorption, which we suggest is due to the formation of a quasi-“three-level system”.     

InP衬底AlAs/In0.53Ga0.47As RTD的研制

报道了InP衬底AlAs/In0.53Ga0.47As/AlAs两垒一阱结构共振隧穿二极管(RTD)器件的研制.结构材料由分子束外延制备,衬底片为(001)半绝缘InP单晶片,器件制作选用台面结构.测得室温下的峰值电流密度为1.06×105 A/cm2,峰-谷电流比为7.4,是国内报道的首例InP材料体系RTD器件.     

Required grading length to eliminate the heterojunction spike in npn In0.52Al0.48As/In0.53Ga0.47As/InP bipolar transistors

Energy-band diagrams have been studied for n-In0.52Al0.48As/p-In0.53Ga0.47As heterojunctions employing different compositional gradings for heterojunction bipolar transistor applications, and the minimum grading widths were calculated for eliminating the conduction-band spike barrier.     

GaAs基InAs/AlSb二维电子气结构的生长优化

采用分子束外延设备 (MBE) , 外延生长了InAs/AlSb二维电子气结构样品.样品制备过程中, 通过优化AlGaSb缓冲层厚度和InAs/AlSb界面厚度、改变AlSb隔离层厚度, 分别对比了材料二维电子气特性的变化, 并在隔离层厚度为5nm时, 获得了室温电子迁移率为20500cm2/V·s, 面电荷密度为2.0×1012/cm2的InAs/AlSb二维电子气结构样品, 为InAs/AlSb高电子迁移率晶体管的研究和制备提供了参考依据.     

InP材料体系RTD的研制

报道了InP衬底AlAs /In0.53Ga0.47As/AlAs结构共振隧穿二极管(RTD)的研制过程.衬底片选用(001)半绝缘InP单晶片,结构材料使用分子束外延(MBE)技术制备,并用PL谱对外延片进行测试,器件采用台面结构.测得RTD器件室温下的峰谷电流比(PVCR)为7.4,峰值电流密度(Jp)为1.06×105A/cm-2,是国内首例成功的InP材料体系RTD.     

High Performance (fT~500GHZ) In0.52Al0.48As/In0.53Ga0.47As/InP Quantum Wire MODFETs Employing Asymmetric Coupled-Well Channels

A coupled-well InAlAs/InGaAs quantum wire MODFET structure is proposed, for which simulations predict improved frequency performance (>500 GHz), over a wider range of V_g, as compared to well/wire devices with a standard MODFET heterointerface. A comparison of several transverse potential well profiles, obtained by varying the placement of a thin barrier within a 100 Å finite well, is presented. In all cases, the quantum wires consist of a 0.1 μm long channel and a 150 Å finite-square-well lateral profile. It has been found that the peak of the electron distribution for the first confined state, as measured from the heterointerface, changes dramatically depending on the location of the thin barrier. For quantum wire structures, realized in the lattice matched system of In_0.52Al_0.48As/In_0.53Ga_0.47As/InP, a change in the barrier location of 25 Å is accompanied by a shift in the carrier peak of more than 40 Å (~20 Å closer to or farther from the spacer-well interface than in the standard MODFET profile). Implications of this are reflected in the current-voltage characteristics (I_d-V_d) and frequency responses (f_T-V_g) of the proposed structures.