Monolithic integration of an AlGaAs/GaAs DH LED with a GaAs FET driver

An AlGaAs/GaAs double heterostructure light emitting diode (LED) and a GaAs field effect transistor (FET) have been monolithically integrated on a GaAs substrate using a combination of liquid phase and molecular beam epitaxies. The electrical isolation between LED and FET has been achieved by inserting a molecular beam-grown high resistivity AlGaAs layer. A linear gate voltage-to-light power transfer characteristic with a 13 ns time constant has been demonstrated.     

Integrated quantum well intersub-band photodetector and lightemitting diode

The authors propose and demonstrate the integration of a quantum well intersub-band photodetector (QWIP) and a light emitting diode (LED) for making large two-dimensional focal plane arrays for thermal imaging applications. The newly developed QWIP technology is combined with the well established LED technology both based on GaAs and related epitaxially grown alloys, such as AlGaAs and InGaAs     

新型光电子光源器件电场分布特性测试研究

本文介绍了应用连续波电光检测法（ＣＷＥＯＰ）对ＧａＡｓ／ＧａＡｌＡｓ双异质结激光器及其列阵和发光管列阵电场分布进行扫描测量的结果，研究了这三种光源器件不同部位的电场分布和电力分布特点及列阵器件的发光均匀性。     

Monolithic integration of GaAs/AlGaAs LED and Si driver circuit

A GaAs/AlGaAs LED has been monolithically integrated with a Si driver circuit composed of ten MOSFETs. The LED replaces the output pad of a 2- μm design rule, standard Si output buffer circuit, so that the overall area remains the same. By applying a stream of voltage pulses to the input of the driver circuit, the LED output has been modulated at rates exceeding 100 MHz     

Relaxation study of AlGaAs cladding layers in InGaAs/GaAs (111)B lasers designed for 1.0-1.1 μm operation

InGaAs/GaAs-based lasers require thick AlGaAs cladding layers to provide optical confinement. Although the lattice mismatch between GaAs and AlGaAs is very low, relaxation may occur due to the thickness requirement for an AlGaAs waveguide of the order of microns. We have studied the relaxation of InGaAs/GaAs lasers with AlGaAs waveguides grown on GaAs (111)B substrates. We have observed by transmission electron microscopy (TEM) that certain AlGaAs layers show a high density of threading dislocations (TDs), whilst other AlGaAs layers remain essentially dislocation free. To explain the experimental results a model based on dislocation multiplication has been developed. TDs in the AlGaAs cladding layers are observed when the critical layer thickness (CLT) for dislocation multiplication has been overcome. Consequently, a design rule based on a modified CLT model for AlGaAs/GaAs (111)B is proposed.     

17 GHz broadband amplifier with 25 dB gain using a 0.3 μmAlGaAs/GaAs/AlGaAs HEMT technology

A broadband amplifier chip based on AlGaAs/GaAs/AlGaAs quantum well FETs with 0.3 μm gate length has been designed and fabricated. The amplifier can be operated with single-ended or differential inputs with an input resistance of 50 Ω. The output signals are differential with both internal load resistances at 100 Ω, the chip area is 1×1 mm², and the power consumption is ~375 mW     

Performance comparison of AlGaAs,GaAs and InGaP tunnel junctions for concentrated multijunction solar cells

Four tunnel junction (TJ) designs for multijunction (MJ) solar cells under high concentration are studied to determine the peak tunnelling current and resistance change as a function of the doping concentration. These four TJ designs are: AlGaAs/AlGaAs, GaAs/GaAs, AlGaAs/InGaP and AlGaAs/GaAs. Time‐dependent and time‐average methods are used to experimentally characterize the entire current–voltage profile of TJ mesa structures. Experimentally calibrated numerical models are used to determine the minimum doping concentration required for each TJ design to operate within a MJ solar cell up to 2000‐suns concentration. The AlGaAs/GaAs TJ design is found to require the least doping concentration to reach a resistance of <10⁻⁴ Ω cm² followed by the GaAs/GaAs TJ and finally the AlGaAs/AlGaAs TJ. The AlGaAs/InGaP TJ is only able to obtain resistances of ≥5 × 10⁻⁴ Ω cm² within the range of doping concentrations studied. Copyright © 2010 John Wiley & Sons, Ltd.     

High-power laser diodes of wavelength 808 nm based on various types of asymmetric heterostructures with an ultrawide waveguide

The parameters of high-power multimode laser diodes featuring a radiation wavelength of 808 nm obtained on the basis of asymmetric heterostructures with an ultrawide waveguide in the systems of AlGaAs/GaAs and (Al)GaInP/GaInAsP/GaAs are compared. In the lasers based on an AlGaAs/GaAs system, the maximum optical power was limited by optical degradation of the SiO₂/Si mirrors and amounted to 4.7 W. In the lasers based on an (Al)GaInP/GaInAsP/GaAs system, the maximum optical power was limited by thermal saturation and equaled 7 W. The obtained results show that the (Al)GaInP/GaInAsP/GaAs system is more reliable from the standpoint of an increase in both the maximum optical power and operation life of lasers.     

9.5-14.5 GHz GaAs HBT 1W MMIC with 55% peak power added efficiency

A fully matched, broadband, high efficiency MMIC power amplifier using AlGaAs/GaAs HBTs has been designed and tested. At 7 V collector bias, this HBT amplifier produced 31 dBm CW peak output power with 9 dB gain and 55% peak power-added efficiency in the 9.5-14.5 GHz band. To the authors' knowledge, this is the highest efficiency ever achieved from a broadband MMIC power amplifier     

Etching behavior of GaAs/AlGaAs multilayer structure during laser beam scanning

The thermochemical etching behavior of GaAs/AlGaAs multilayer structure during laser beam scanning has been studied. The etch rate changes between GaAs and AlGaAs epilayers as the etching process proceeds through the layered sample. The phenomenon can be explained by the difference of thermal parameters of the heterojunction interface. The local temperature rise from laser irradiation has been calculated to investigate etching characteristics for GaAs and AlGaAs. It is concluded that the good thermal confinement at GaAs/AlGaAs interface produces the wider etch width of GaAs layer than that of AlGaAs layer in GaAs/AlGaAs multilayer. The maximum etch rate of the GaAs/AlGaAs multilayer was 32.5 μm/sec and the maximum etched width ratio of GaAs to AlGaAs was 1.7.     

Trap studies in GaInP/GaAs and AlGaAs/GaAs HEMT's by means oflow-frequency noise and transconductance dispersion characterizations

The presence of traps in GaInP/GaAs and AlGaAs/GaAs HEMT's was investigated by means of low frequency noise and frequency dispersion measurements. Low frequency noise measurements showed two deep traps (E _a1=0.58 eV, E_a2=0.27 eV) in AlGaAs/GaAs HEMT's. One of them (E_a2) is responsible for the channel current collapse at low temperature. A deep trap (E_a1'=0.52 eV) was observed in GaInP/GaAs HEMT's only at a much higher temperature (~350 K). These devices showed a transconductance dispersion of ~16% at 300 K which reduced to only ~2% at 200 K. The dispersion characteristics of AlGaAs/GaAs HEMT's were very similar at 300 K (~12%) but degraded at 200 K (~20%). The low frequency noise and the transconductance dispersion are enhanced at certain temperatures corresponding to trap level crossing by the Fermi-level. The transition frequency of 1/f noise is estimated at 180 MHz for GaInP/GaAs HEMT's and resembles that of AlGaAs/GaAs devices     

High-power InAlGaAs/GaAs and AlGaAs/GaAs semiconductor laser arrays emitting at 808 nm

Molecular beam epitaxy (MBE) growth, device fabrication, and reliable operation of high-power InAlGaAs/GaAs and GaAlAs/GaAs laser arrays are described. Both InAlGaAs/GaAs and AlGaAs/GaAs laser arrays reached maximum continuous wave output powers of 40 W at room temperature. The external quantum efficiency was 50% and 45% for the InAlGaAs/GaAs and AlGaAs/GaAs laser arrays, respectively. Threshold current density for InAlGaAs/GaAs and AlGaAs/GaAs lasers was 303 A/cm/sup 2/ and 379 A/cm/sup 2/, respectively. While the current of AlGaAs laser arrays went up significantly after 1000 h of operation at a constant power of 40 W, InAlGaAs laser arrays had an increase in the injection current of less than 4% after 3000 h at 40 W.     

LP－MOCVD生长InGaAs／GaAs量子阱

用低压ＭＯＣＶＤ（ＬＰ－ＭＯＣＶＤ）生长三种不同的ＩｎＧａＡｓ／ＧａＡｓ应变层量子阱材料，其中两种含ＡｌＧａＡｓ限制层。结果表明，ＡｌＧａＡｓ限制层对量子阱的发光强度影响很大，与没有ＡｌＧａＡｓ限制层的结果相比，带ＡｌＧａＡｓ限制层的结构的发光强度要强一个数量级以上。在低温（１８Ｋ）ＰＬ光谱图中，我们看到，除了存在主峰以外，在主峰两侧还各有一个子峰，这些子峰可能与量子阱的质量有关。     

GaAsSb for heterojunction bipolar transistors

The advantages of using GaAsSb in heterojunction bipolar transistors (HBT) are discussed with emphasis on two recent experimental results in the AlGaAs/GaAsSb material system. The performances of a prototype n-p-n AlGaAs/GaAsSb/GaAs double HBT (DHBT) that exhibits stable current gain with maximum collector current density of 5×10 ⁴ A/cm², and a p-n-p AlGaAs/GaAs HBT with a superlattice GaAsSb emitter ohmic contact which has a specific contact resistivity of 5±1×10^-7 Ω-cm² across the sample, are examined     

Analysis of AlGaAs/GaAs solar cell structures by opticalreflectance spectroscopy

The control of the thickness and composition of the GaAs cap and AlGaAs window layers is essential to the fabrication of high-efficiency AlGaAs/GaAs heteroface solar cells. The use of optical reflectance spectroscopy for the analysis of these structures is presented. The calculation of the reflectance of a system of thin films is described along with the computer program, REFIT, for the analysis of GaAs cell structures. Results are presented for structures at different stages in the solar cell fabrication process, and the method is applied to the analysis of the oxidation of high AlAs mole fraction AlGaAs layers     

Radiance of small-area high-current-density electroluminescent diodes

Optical power radiated into a solid angle per unit area of emitting surface (radiance) is a basic measure of the usefulness of an electroluminescent device to be used as a communications-system source. Dc radiance values from about 20 to more than 100 W/sr/cm²have been obtained for various small-area GaAs and AlGaAs diodes operated at current densities that yielded an operating half-life of at least several thousand hours. These radiance values are two to three orders of magnitude larger than those obtained with relatively large-area commercial light-emitting diode (LED) indicator lamps.     

Optical characteristics of InGaP/GaAs HPTs

In this paper, we examined the optical characteristics of InGaP/GaAs heterojunction phototransistor (HPT) directly compared with AlGaAs/GaAs HPT for the first time. Because of its inherent good electrical properties, the InGaP/GaAs HPT produced a high optical gain of about 61 at V_C=3 V, I_B=2 μA, for an input optical power of 1.23 μW. This is 2.5 times as high as that of the AlGaAs/GaAs HPT. In the transient response, the InGaP/GaAs HPT was a little inferior to the AlGaAs/GaAs HPT. This is due to the longer time delay caused by the photo-generated hole accumulation at the interface of heterojunction. The extended response time can be overcome by using a small load resistance in conjunction with the advantage of the superior optical gain     

Low 1/f noise characteristics of AlGaAs/GaAs heterojunction bipolartransistor with electrically abrupt emitter-base junction

It is shown that the use of an electrically abrupt emitter-base junction considerably reduces the 1/f noise of self-aligned AlGaAs/GaAs heterojunction bipolar transistor (HBT). Although this device does not have depleted AlGaAs ledge passivation layer, the low-frequency noise spectra show a very low 1/f noise corner frequency of less than 10 kHz, which is much lower than previously reported value of about 100 kHz from conventional passivated or unpassivated AlGaAs/GaAs HBT's. Except for a residual generation-recombination (g-r) noise component, the noise power is comparable to that of Si BJT. It is also found that the low-frequency noise power of the AlGaAs/GaAs HBT is proportional to the extrinsic GaAs base surface recombination current square. Unlike the other HBT's reported, the noise sources associated with interface state and emitter-base (E-B) space charge region recombination are not significant for our device     

Kinetics of red AlGaAs light-emitting diodes degradation

The kinetics of the gradual degradation of red AlGaAs light-emitting diodes (LED) has been studied. This degradation has been shown to be due to diffusion of Zn atoms from the GaAs substrate to the p-n⁺ junction. The gradual degradation kinetics has been described on the basis of a diffusion model. It has been ascertained that the Zn atom diffusion process is not recombination-enhanced. At the same time the process of elastic stress relaxation, occuring at the initial stage of the LED degradation, is enhanced by the flowing current.     

A 3.3-V 21-Gb/s PRBS generator in AlGaAs/GaAs HBT technology

We present a pseudorandom bit sequence (PRBS) generator that outputs a 2⁷-1 bit pattern at rates up to 21 Gb/s. The circuit is implemented in a 40-GHz AlGaAs/GaAs heterojunction bipolar transistor (HBT) standard production process, operates from a single 3.3-V power supply, and consumes 1.1 W of power. We discuss variations of PRBS architecture and digital circuit topologies which exploit unique characteristics of AlGaAs/GaAs HBT devices. The work demonstrates the feasibility of using AlGaAs/GaAs HBT technology with low-voltage/low-power design techniques in complex high-speed circuits