Effects of high temperature annealing on the device characteristics of Ga0.52In0.48P/GaAs and Al0.52In0.48P/GaAs heterojunction bipolar transistors

GaInP/GaAs and AlInP/GaAs heterojunction bipolar transistor (HBT) structures were grown by low pressure metalorganic vapor phase epitaxy and annealed at various temperatures up to 675°C for 15 min. Subsequent comparisons with HBTs fabricated on both annealed and unannealed control samples showed no effects for annealing up to and including 575°C, but significant changes in the electrical characteristics were observed at an annealing temperature of 675°C. For the GaInP/GaAs devices, the base current increased by a significant amount, reducing the gain and increasing the base current ideality factor from 1.07 to 1.9. Photoluminescence and electrical measurements on the structures indicated that both the emitter and base were affected by an increase in the recombination times in those regions. These effects were attributed to an out-diffusion of hydrogen from the base during annealing. The emitter of the AlInP/GaAs HBT was affected less by the hydrogen diffusion because of the larger bandgap. These observations have important implications for device performance dependence on the details of the temperature/time profile subsequent to the base growth.     

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.     

Very high electron mobility In0.8Ga0.2As heterostructure grown by molecular beam epitaxy

A very high electron mobility pseudomorphic In_0.8Ga_0.2As heterostructure is successfully grown on InP both by the elimination of the overshoot of flux densities and by the precise control of the flux ratio through a new calibration technique of RHEED oscillations in an MBE system. The critical layer thickness for the pseudomorphic growth of InGaAs on InP is found to follow the energy balance model, and a very high 2DEG mobility of over 1.5 and 16 m²/Vs at 293 and 10 K, respectively, is obtained.     

Highly strained ln0.35Ga0.65As/GaAs layers grown by molecular beam epitaxy for high hole mobility transistors

We have grown highly strained In_0.35Ga_0.65As layers on GaAs substrates by molecular beam epitaxy to improve the performance of high hole mobility transistors (HHMTs). The mobility and sheet hole concentration of double side doped pseudomorphic HHMT structures at room temperature reached 314 cm2/V-s and 1.19 × 10¹² cm⁻², respectively. Photoluminescence measurements at room temperature show good crystalline quality of the In^0.35Ga_0.65As layers. This study suggests that the performance of HHMTs can be improved by using high-quality In_0.35Ga_0.65As layers for the channel of double side doped heterostructures pseudomorphically grown on GaAs substrates.     

应变In0.20 Ga0.80As／GaAs单量子阱结构的光谱研究

报道了用光致发光光谱，吸收光谱和光电流谱研究具有相同组伊阱宽，不同覆盖层厚度的应变Ｉｎ０．２０Ｇａ０．８０Ａｓ／ＧａＡｓ单量子阱结构的实验结果，结果理论计算，观察到ＧａＡｓ覆盖层厚度对单量子阱结构的材料质量，应力驰豫和发光淬灭机制的影响，确定了各样品应变值和导带不连续因子Ｑｃ，并讨论了这种结构发光机制。     

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).     

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-gain Al0.48In0.52As/Ga0.53As vertical n-p-n heterojunction bipolar transistors grown by molecular-beam epitaxy

We report the first vertical n-p-n heterojunction bipolar transistors formed in the (Al,In)As/(Ga,In)As alloy system. The structures grown by molecular-beam epitaxy (MBE) use a wide band-gap (Eg = 1.44 eV) Al0.48In0.52As emitter on a lower band gap (Eg = 0.73 eV) Ga0.47In0.53As base 2500 Å in width. Transistors with both abrupt and graded heterojunction emitters were demonstrated with dc current gains of 140 and 280, respectively, at a collector current of 15 mA. The (Al,In)As/(Ga,In)As heterojunction transistors offer the attractive possibility of optical integration with long wavelength lasers and photodetectors.     

LPE growth of In0.48Ga0.52As0.01P0.99 lattice-matched to GaAs from an In melt rich in P

High-quality quaternary In0.48Ga0.52As0.01P0.99 crystals lattice-matched to GaAs substrates were grown by liquid phase epitaxy from an In melt rich in P. The peak wave-length and spectral width of the photoluminescence were 652.5 nm and 13.4 nm at room temperature, respectively.     

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.     

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.     

T形栅In0.52Al0.48As/In0.6Ga0.4As MHEMTs功率器件

利用电子束光刻技术制备了200nm栅长GaAs基T型栅InAlAs/lnGaAs MHEMT器件.该GaAs基MHEMT器件具有优越的直流、高频和功率性能,跨导、饱和漏电流密度、阈值电压、电流增益截止频率和最大振荡频率分别达到510mS/mm,605mA/mm,-1.8V,138GHz和78GHz.在8GHz下,输人功率为-0.88(2.11)dBm时,输出功率、增益、PAE、输出功率密度分别为14.05(13.79)dBm,14.9(11.68)dB,67.74(75.1)%,254(239)mW/mm,为进一步研究高性能GaAs基MHEMT功率器件奠定了基础.     

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.     

Highly confined two-dimensional electron gas in an In0.52AI0.48As/In0.52Ga0.47As modulation-doped structure with a strained InAs quantum well

This paper examines a detailed analysis by Shubnikov-de Haas measurements of the effective mass of two-dimensinal electron gas (2DEG) in an In_0.52Al_0.48As/ In_0.53Ga_0.47As modulation-doped (MD) structure with an InAs quantum well inserted into the InGaAs channel (InAs-inserted channel). The measured effec-tive mass of 2DEG in the InAs-inserted-channel MD structure is in good agreement with the calculated one of the strained InAs layer on In_0.53Ga_0.47As. This indicates that almost all of the 2DEG forms in the strained InAs quantum well. These results show that the InAs-inserted-channel MD structure improves the electron confinement, since the 2DEG is confined in the InAs quantum well with the thickness of 4 nm.     

Very high purity In0.53Ga0.47As grown by molecular beam epitaxy

Very high purity In0_0.53Ga_0.47As layers were grown by molecular beam epitaxy (MBE). Origins ofn-type impurities in undoped In_0.53Ga_0.47As grown on an InP:Fe substrate were systematically examined. The most possible origins were impurities diffusing from the InP:Fe substrate and those contained in As molecular beam. These impurities were dramatically reduced by using an InAlAs buffer layer and a growth condition of high substrate temperature and low As pressure. The lowest electron concentration of the In0_0.53Ga_0.47As layer wasn = 1.8 × 10¹³ cm_-3 with mobilitiesμ = 15200 cm²/Vs at 300 K andμ = 104000 cm²/Vs at 77 K.     

(In,Ga)As/InP n-p-n heterojunction bipolar transistors grown by liquid phase epitaxy with high DC current gain

Experimental results on heterojunction bipolar transistors made in liquid phase epitaxial (In,Ga)As and InP layers on InP substrates are described. The (In,Ga)As base layer was doped with manganese during growth and contacts were made to it by beryllium ion implantation. The maximum measured dc current gain β of these devices was in excess of 500. These devices also demonstrate for the first time in an InP-based system, the inverted emitter-down heterojunction transistor structure with a base contact, which yields a minimized collector-base junction area and should significantly improve high-frequency performance.     

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.     

Hall and photoluminescence studies of effects of the thickness of an additional In0.3Ga0.7As layer in the center of In0.15Ga0.85As/Al0.25Ga0.75As/GaAs high electron mobility transistors

In order to reduce the noise and carrier–donor scattering and thereby increase the carrier mobility of the pseudomorphic AlGaAs/InGaAs high electron mobility transistors (pHEMTs), we have grown Al_0.25Ga_0.75As/In_0.15Ga_0.85As/In_0.3Ga_0.7As/GaAs pHEMTs with varied In_0.3Ga_0.7As thickness, and studied the effects of the In_0.3Ga_0.7As thickness on the electron mobility and sheet density by Hall measurements and photoluminescence measurements. We calculated the electron and hole subbands and obtained good agreement between calculated and measured PL energies. It was found that the additional In_0.3Ga_0.7As layer could be used to reduce the carrier–donor scattering, but due to the increased interface roughness as the In_0.3Ga_0.7As layer becomes thicker, the interface scattering reduced the electron mobility. An optimal thickness of the In_0.3Ga_0.7As was found to be 2 nm.     

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.