Planar photodiodes made from vapour-phase epitaxial InxGa1?xAs

Planar photodiodes for the 1.0?1.3 ?m wavelength range have been fabricated by diffusing Zn into vapour-phase epitaxial InxGa1?xAs grown on a GaAs substrate. For compositions x=0?0.31, the dark current and spectral response are reported. The dark-current density for x=0.17 was as low as 5.4 × 10?6 A/cm2 at VB/2.     

Pulsed Laser Irradiation of GaAs-Based Light-Emitting Structures

Semiconductors - The effects of KrF excimer laser pulses on the crystalline and optical properties of structures with four InxGa1 – xAs/GaAs quantum wells (x ranging from 0.08 to 0.25) are...     

Effects of Doping of Bragg Reflector Layers on the Electrical Characteristics of InGaAs/GaAs Metamorphic Photovoltaic Converters

Semiconductors - The current–voltage characteristics of InxGa1 –xAs/GaAs metamorphic photovoltaic converters with built-in n-InGaAs/InAlAs Bragg reflectors are studied at an indium...     

Doping-Dependent Nonlinear Electron Mobility in GaAs|InxGa1 –xAs Coupled Quantum-Well Pseudo-Morphic MODFET Structure

Semiconductors - We analyze the asymmetric delta-doping dependence of nonlinear electron mobility μ of GaAs|InxGa1 –xAs double quantum-well pseudo-morphic modulation doped field-effect...     

InGaAs／GaAs自组织量子点光致发光特性研究

用PL谱测试研究了GaAs和不同In组份InxGa1-xAs(x=0.1,0.2,0.3)覆盖层对分子外延生长的InAs/GaAs自组织量子点发光特性的影响,用InxGa1-xAs外延层覆盖InAs/GaAs量子点,比用GaAs做 其发光峰能量向低有端移动,发光峰半高度变窄,量子点发光峰能量随温度的红移幅度较小,理论计算证实这是由于覆盖层InxGa1-xAs减小了InAs表面应力导致发光峰红移,而In元素有效抑制了InAs/GaAs界面组份的混杂,量子点的均匀性得到改善,PL谱半高宽变窄,用InGaAs覆盖的In0.5Ga0.5As/GaAs自组织量子点实现了1．3μm发光,室温下PL谱半高宽为19．2meV,是目前最好的实验结果。     

Growth conditions to achieve mobility enhancement in AlxGa1?xAs-GaAs heterojunctions by m.b.e.

Modulation doped Al0.25Ga0.75As-GaAs heterojunctions have been prepared by molecular beam epitaxy (m.b.e.). Al0.25Ga0.75As layers were doped with Si to a level of ~ 3 × 1017 cm?3, whereas the GaAs layers were either unintentionally doped, doped lightly n-type with Sn, or doped lightly p-type with Be. Heterojunction structures having single and multiple periods have shown enhanced mobility only with the AlxGa1?xAs layer at the surface and the GaAs layer underlying. These results represent the first report that electrons spill over only into the underlying GaAs layer from the top AlxGa1?xAs layer.     

GaAs-GaAlAs anti-Stokes light convertor

A multilayer heterojunction device has been manufactured and used for efficient anti-Stokes light conversion. The device consists of six layers: p GaAs, n GaAs, n GaxAl1?xAs, p GayAl1?yAs, p GaxAl1?xAs and p GaAs, essentially forming a GaAs photodiode coupled with a GaAlAs l.e.d. Avalanche multiplication of photoexcited carriers is used to increase the l.e.d. driving current.     

基于低温In_xGa_(1-x)P组分渐变缓冲层的InP/GaAs异质外延

采用低温GaAs与低温组分渐变InxGa1-xP作为缓冲层,利用低压金属有机化学气相外延(LP-MOCVD)技术,在GaAs(001)衬底上进行了InP/GaAs异质外延实验。实验中,InxGa1-xP缓冲层选用组分线性渐变生长模式(xIn0.49→1)。通过对InP/GaAs异质外延样品进行双晶X射线衍射(DCXRD)测试,并比较1.2μm厚InP外延层(004)晶面ω扫描及ω-2θ扫描的半高全宽(FWHM),确定了InxGa1-xP组分渐变缓冲层的最佳生长温度为450℃、渐变时间为500s。由透射电子显微镜(TEM)测试可知,InxGa1-xP组分渐变缓冲层的生长厚度约为250nm。在最佳生长条件下的InP/GaAs外延层中插入生长厚度为48nm的In0.53Ga0.47As,并对所得样品进行了室温光致发光(PL)谱测试,测试结果表明,中心波长为1643nm,FWHM为60meV。     

生长在In_xGa_（1－x）As（001）衬底上应变薄层GaAs的电子能带结构

采用经验的紧束缚方法对生长在ＩｎｘＧａ１－ｘＡｓ（００１）衬底上的应变薄层ＧａＡｓ的电子能带结构进行了计算。应变对能带结构的影响按标度定则进行计算，其中标度指数根据对畸变势常数的实验值进行拟合而确定。给出了ＧａＡｓ／ＩｎｘＧａ１－ｘＡｓ（００１）能带结构随衬底合金组分ｘ的变化关系，讨论了应变对能带色散关系的影响。     

MBE-Grown InxGa1 –xAs Nanowires with 50% Composition

Semiconductors - In a particular case of Au-catalyzed InxGa1 –xAs nanowires, wide compositional tuning has been obtained using metal organic vapor-phase epitaxy, which remains difficult for...     

Electroluminescent GaAs?GaxAl1?xAs heterostructure diodes with negative resistance at low temperatures

GaAs?GaxAl1?xAs 4-layer heterostructures can exhibit a negative resistance at low temperatures if the p-type layers are doped with Si and Ge, respectively. A region of high resistivity is formed because of freezeout of carriers on deep levels. The effect can be described by Lampert's model of double injection.     

Effect of d.c. bias level on the spectrum of GaAs lasers operated with short pulses

Experimental results on stripe-geometry GaAs/GaxAl1?xAs lasers show that the emission spectrum when operated with short pulses is very dependent on the d.c. bias level. If the bias is below threshold, many modes are excited and the spectral bandwidth is about 30 ?, but a bias just above threshold ensures virtually single-mode operation with about 1 ? bandwidth.     

Transition from an Exponential to Linear Increase in the Energy Density of the Spectral Component of Picosecond Stimulated Emission by GaAs upon Gain Saturation

Semiconductors - At the beginning of high-power optical picosecond pumping of the GaAs layer of the AlxGa1 – xAs–GaAs–AlxGa1 – xAs...     

V-DH laser: a laser with a V-shaped active region grown by metalorganic c.v.d.

A single mode c.w. AlxGa1?xAs/GaAs laser was made by metalorganic c.v.d. A double heterostructure with a V-shaped active region and a junction stripe geometry was grown on a groove-etched substrate. The minimum c.w. threshold current and the maximum differential quantum efficiency obtained were 15 mA and 65% (250 ?m length cavity). The laser's beam shape was nearly circular, with an aspect ratio from 1.3 to 1.4.     

High mobility GaAs-AlxGa1?xAs single period modulation-doped heterojunctions

Single period modulation-doped structures composed of an AlxGa1?xAs layer, part of which is doped with Si, on top of an undoped GaAs layer have been grown by molecular beam epitaxy. The films were characterised using Hall effect measurements carried out at temperatures between 10 and 300 K. With 50?75 ? thick undoped (Al, Ga)As layers near the interface, mobilities in excess of 115000 cm2/Vs at 10 K and 7450 cm2/Vs at 300 K have been achieved for an average doping concentration of ?5×1016 cm?3. These are some of the highest mobilities as yet obtained from modulation-doped structures, and represent an increase in mobility over equivalently doped GaAs by about a factor of 20 at 10 K and by a factor of 2 at 300 K.     

Characterization of GaNxAs1-x Alloy Grown on GaAs by Molecular Beam Epitaxy

Ga Nx As1 - x,the combination of small amount of nitrogen and Ga As,has beenexperimentally observed with the band gaps several hundreds me V lower than that ofGa As[1～ 4] .The alloy has attracted considerable attention in the applicat...     

Temporal resolution of an AlxGa1?xAs/GaAs bias-free photodetector

We report on the measurement of the temporal resolution limit of a recently reported AlxGa1?xAs/GaAs bias-free photodetector. When tested by dual synchronously pumped dye laser pulses with a repetition rate of 80 MHz and an attenuated energy per pulse of 30 pJ, the detector shows a resolution limit of ? 65 ps.     

Functional Dependences of the Maximum Energy Density of the Spectral Component of Stimulated Picosecond Emission by GaAs upon Gain Saturation. The Residual Characteristic Emission Relaxation Time

Semiconductors - During high-power optical picosecond pumping of the GaAs layer of an AlxGa1 – xAs–GaAs–AlxGa1 – xAs heterostructure, stimulated...     

Two-dimensional electron gas m.e.s.f.e.t. structure

The first m.e.s.f.e.t. structure is reported in which the channel near pinch-off is occupied by a two-dimensional electron gas accumulated at the interface of a GaAs(N)-AlxGa1?xAs(N) heterojunction. Experimental data are in good agreement with theoretical calculations.     

Electron transport through the MOCVD grown GaAs/AlGaAs/GaAs heterojunction barrier

We investigated the current/voltage characteristics of n+GaAs/undoped AlxGa1?xAs (200 A)/n+GaAs heterostructures grown by the metalorganic chemical vapour deposition (MOCVD) method between 77 K and 300 K. Both the voltage dependence and the temperature dependence of the current were in good agreement over a wide current range with the calculated results of the tunnelling and thermionic emission current.