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.     

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.     

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.     

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.     

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.     

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.     

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.     

InP MESFET with In0.53Ga0.47As/InP heterostructure contacts

Source and drain contacts for an InP MESFET were prepared by an Au/Ni/In0.53Ga0.47As/InP layered structure, without a metal alloying process. A highly conductive In0.53Ga0.47As layer grown on an InP active layer reduced the gate-source resistance. A maximum DC transconductance of 16 mS has been obtained for an InP MESFET with 1.2×190 ?m gate dimensions and a pinch-off voltage of ?0.7 V.     

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...     

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).     

A study of alloyed AuGeNi/Ag/Au based ohmic contacts on the Al0.48In0.52As/Ga0.47In0.53As system

Very low resistance alloyed NiGeAuAgAu ohmic contacts have been fabricated to the Al_0.48In_0.52As/Ga_0.47In_0.53As heterosystem. A thin capping layer of GalnAs was used to inhibit Al oxidation at the surface. Unlike NiGeAgAu ohmic metallization containing ≈;25% Ag commonly used for contacting GaAs based semiconductors at Cornell, the Ag concentraiton was reduced to ≈;10%. AES/sputtering depth profiles indicated that this allowed controlled dissolution of the nonconducting AlInAs top layer by the metallization which eventually interacted with the GalnAs without depleting it of In due to the strong Ag-In affinity. The stoichiometry of the conducting GalnAs, in contact with the reacted metals, was thus maintained and this yielded specific transfer resistances ≈;0.06 ohm · mm, the lowest to date.     

High-performance Al/sub 0.48/In/sub 0.52/As/Ga/sub 0.47/In/sub 0.53/As MSM-HEMT receiver OEIC grown by MOCVD on patterned InP substrates

Reports the first demonstration of a new long-wavelength receiver OEIC comprising an AlInAs/GaInAs MSM detector and an AlInAs/GaInAs HEMT preamplifier. The layer structure was grown by LP-MOCVD on patterned InP substrates, which allowed independent optimisation of the MSM detector and HEMT preamplifier. The MSM detector showed the lowest leakage current yet reported and the HEMT exhibited a transconductance of 260 mS/mm. An excellent receiver response to 1.7 Gbit/s NRZ signals has been obtained.<>     

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.     

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.     

In0.53Ga0.47As/InP红外探测器材料与线列器件

采用LPMOCVD技术生长了In0.53Ga0.47As红外探测器器件结构材料,其晶格失配为2.19×10-4.利用锌扩散制备探测器单元和1×256线列器件,光谱响应范围为O.90～1.70 μm,量子效率为73%,在零偏压下,暗电流为1.62×10-8A,动态零压电阻为2.72×105Ω.单元探测器波段探测率为1.71×1012cmHz1/2W-1.     

Long-wavelength In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As large-area avalanche photodiodes and arrays

Large-area (500-/spl mu/m diameter) mesa-structure In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiodes (APDs) are reported. The dark current density was /spl sim/2.5/spl times/10/sup -2/ nA//spl mu/m/sup 2/ at 90% of breakdown; low surface leakage current density (/spl sim/4.2 pA//spl mu/m) was achieved with wet chemical etching and SiO/sub 2/ passivation. An 18 /spl times/ 18 APD array with uniform distributions of breakdown voltage, dark current, and multiplication gain has also been demonstrated. The APDs in the array achieved 3-dB bandwidth of /spl sim/8 GHz at low gain and a gain-bandwidth product of /spl sim/120 GHz.     

Optical tuning of monolithic In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As/InP modulation-doped field-effect transistor oscillators at X and R band

The authors have experimentally studied the optical control and optical tuning characteristics of monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As modulation-doped field-effect transistor (MODFET) oscillators operating in the X and R bands. For a 20 mu W intrinsic photoexcitation on the device, the maximum frequency shift for the X- and R-band oscillators was 8.7 and 11.7 MHz, respectively.<>     

Direct optical injection locking of monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As MODFET oscillators

The authors have fabricated monolithically integrated In/sub 0.53/Ga/sub 0.47/As/In/sub 0.52/Al/sub 0.48/As 0.25 mu m gate modulation-doped field effect transistor (MODFET) oscillators. The results of direct optical subharmonic injection locking of these oscillator circuits at 10.159 and 19.033 GHz are presented.<>     

Geiger mode operation of an In/sub 0.53/Ga/sub 0.47/As-In/sub 0.52/Al/sub 0.48/As avalanche photodiode

Low-temperature photon counting with gated mode quenching is demonstrated with separate absorption, charge, and multiplication avalanche photodiodes that have an In/sub 0.52/Al/sub 0.48/As multiplication layer. A minimum of ten dark counts per second and single-photon detection efficiency of 16% were achieved at 130 K.