Low resistance alloyed ohmic contacts to Al0.48In0.52As/n+-Ga0.47In0.53As

A low ohmic contact resistance metallurgy and associated alloy cycles have been developed for applications to Al0.48In0.52As/Ga0.47In0.53As MODFETs (HEMTs). The metallurgy involves sequentially evaporated Ni/Ge/Au/Ag/Au layers followed by transient thermal alloy cycles. This resulted in low transfer resistances ~0.06 ?mm to the underlying GalnAs layer for alloying temperatures to ~480°C.     

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.     

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.     

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.     

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.     

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。     

Sheet electron concentration at the heterointerface in Al0.48In0.52As/Ga0.47In0.53As modulation-doped structures

Sheet electron concentration at the heterointerface in Al0.48In0.52As/Ga0.47In0.53As modulation-doped structures has been calculated as a function of the spacer layer thickness, the doping concentration in Al0.48In0.52As and the lattice temperature. The calculated results were compared with those for Al0.3Ga0.7As/GaAs structures and also with the experimental data. It is shown that, compared with AlGaAs/GaAs about 1.5 times higher sheet electron concentration can be obtained in AlInAs/GaInAs at the same doping level, which is in good agreement with the experimental results.     

Room-temperature operation of Ga0.47In0.53As/AI0.48In0.52As resonant tunnelling diodes

The first room-temperature operation of Ga0.47In0.53As/Al0.48In0.52As resonant tunnelling (RT) diodes is reported. The peak/valley ratio of the current is as high as 4:1 at room temperature and is 15:1 at 80 K. These are the highest values of peak/valley ratio at the respective temperatures, reported so far, in this material system. The position of the peak in the current/voltage characteristic also showed good agreement with that obtained from an electron tunnelling transmission calculation.     

Thermal stability of Al0.48In0.52As/Ga0.47In0.53As/InP heterostructure and its improvement by phosphidization

A drastic decrease in the sheet carrier concentration of modulation-doped Al_0.48In_0.52As/Ga_0.47In_0.53As/InP heterostructures has been observed after O₂ plasma treatment followed by thermal treatment up to 350°C. The decrease in sheet carrier concentration, which is speculated to be caused by both plasma damage and impurities penetrating from the surface of the epilayer, can be suppressed substantially by using PH₃ plasma treatment prior to the O₂ plasma and thermal treatments.     

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。     

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。     

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.     

Dependence of electron mobility on spacer thickness and electron density in modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions

Modulation-doped Ga0.47In0.53As/Al0.48In0.52As heterojunctions were grown by molecular beam epitaxy. Electron mobilities were measured at room temperature and 77 K as a function of undoped Al0.48In0.52As spacer layer thickness and sheet carrier concentration. Enhanced mobilities were as high as 10 900 cm2V?1s?1 at room temperature and 55 500 cm2V?1s?1 at 77 K in these samples with sheet carrier concentrations at 1 33 × 1012 cm?2 (room temperature) and 1.26 × 1012 cm?12 (77 K).     

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.     

Mechanisms of negative resistivity and generation of terahertz radiation in a short-channel In0.53Ga0.47As/In0.52Al0.48As transistor

Semiconductors - The effect of negative resistivity observed at anomalously low voltages in output characteristics of modulation-doped In0.53Ga0.47As/In0.52Al0.48As field-effect transistors is...     

Ohmic contacts on p-type Ga0.47In0.53As/InP

Ohmic contacts of Au and Ag based Zn containing alloys on p-type Ga_0.47In_0.53As have been studied using intermediate layers of Ti and Ni, respectively. Low specific contact resistance in the order of 10⁻⁵ Ωcm² are achieved. In case of AuZn alloy, the Ti intermediate metal layer causes higher contact resistances together with a worse contact morphology in contrast to Ni intermediate layers. However for AgZn contacts Ti adherent layers improve the contact resistances, especially for lower alloying temperatures. Moreover these contacts exhibit significant smoother interfaces as revealed by TEM micrographs. Thus AgZn contacts apply best to low resistive contacting of very thin p-layers forming e.g. the base of a ballistic device.     

Analysis of 14nm technology node In0.53Ga0.47As nFinFET integrated with In0.52Al0.48As cap layer for high-speed circuits

CMOS (Complementary Metal-oxide-semiconductor) based high-speed applications in the sub-14 nm technology node using InGaAs Fin field-effect-transistors (FinFETs) confront with inevitable effect in form of interface traps upon integration of dielectric layer with InGaAs material. In this work, we have explored the impact of the traps on short channel effects (SCEs) and a technique of abating the effect of interface traps by introducing In_0.52Al0.₄₈As cap layer. Proposed work reforms the device by varying the cap layer thickness (Tcap), doping concentrations of cap layer and underlap region. The effect of traps on intrinsic delay, work function variation and SCEs was investigated to assess the trend on devices with In_0.52Al_0.48As cap layer. It has been observed that introduction of Tcap improves SCEs and helps to mitigate the effect of interface traps. SCEs can be additionally diminished by presenting underlap fin length at the cost of higher delay. The experimental results show the value of subthreshold swing = 149.54 mV/decade, drain-induced barrier lowering = 38.5 mV V^?1 and delay = 1.1 ps for T_cap = 4 nm without underlap fin length structure for traps concentration of 10¹² cm^?2eV^?1. Thus, significant improvement has been seen in SCEs and delay performance in FinFET structure with cap layer.     

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.     

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.