磷化铟的化学机械抛光技术研究进展

磷化铟单晶作为一种重要的外延层衬底材料被广泛应用于光电器件.衬底外延生长和电子器件制备要求磷化铟晶片表面具有极低的表面粗糙度、无表面/亚表面损伤和残余应力等,需对磷化铟晶片表面进行抛光加工,其表面质量决定了后续的外延层质量并最终影响磷化铟基器件的性能.综述了磷化铟晶体化学机械抛光(CMP)技术进展;介绍了磷化铟表面的化学反应原理、CMP去除机理;详细分析了磷化铟抛光液组分及pH值、抛光工艺参数(抛光压力、抛光盘转速、抛光垫特性、磨料种类、粒径及浓度)等对磷化铟抛光质量的影响;介绍了磷化铟抛光片的清洗工艺,并对磷化铟CMP的后续研究方向提出一些建议.     

Room-temperature, CW operation of lattice-matched long-wavelengthVCSELs

Continuous-wave operation of vertical-cavity surface-emitting lasers lattice matched to InP and grown with one epitaxial step is presented. These lasers combine highly reflective AlAsSb/AlGaAsSb mirrors with a double-intracavity contacted structure based on thick InP contact layers     

Influence of mismatch of the lattice parameters on the structural, optical, and transport properties of InGaAs layers grown by molecular beam epitaxy on InP(100) substrates

The influence of mismatch stress on the structural, optical, and transport properties of thick InGaAs layers grown on InP(100) substrates by molecular-beam epitaxy is investigated. It is found that layers having tensile stress can be grown with a greater mismatch than compressively stressed layers before plastic relaxation sets in. The critical mismatch for thick InGaAs layers is not described with sufficient accuracy by either the mechanical equilibrium model or the energy balance model. The range of mismatches required to obtain high carrier mobilities and high radiative recombination efficiencies in InGaAs layers grown on InP substrates is much narrower than the pseudomorphic growth range. The maximum mobilities and minimum widths of the photoluminescence peak are attained in layers matched with the substrate in terms of the lattice parameter and also in slightly gallium-enriched layers. The compositional dependence of the width of the band gap is investigated with allowance for the influence of stress. Fiz. Tekh. Poluprovodn. 31, 19–22 (January 1997)     

Single-mode optical waveguides and phase modulators in the InP material system

The characteristics of several different single-mode optical waveguides in the InP material system are discussed. Slab-coupled rib waveguides in GaInAsP (lambda_{gap} approx 1 mum) epitaxial layers grown on InP have shown propagation losses as low as 1.7 cm^-1at 1.3 μm and 2.7 cm^-1at 1.15 μm. Oxide-confined InP rib guides fabricated using a lateral overgrowth technique have losses of about 1.5 cm^-1at 1.15 μm. Three-guide couplers have been made by fabricating three parallel oxide-confined guides in close proximity. InP p+-n-n+ guides capable of modulating TE-polarized radiation have been fabricated using epitaxial techniques and Be-ion implantation. By measuring the phase difference between the TE-like and TM-like modes as a function of applied voltage, an estimate of the r41electrooptic coefficient in InP at 1.3 μm that is in good agreement with a previously reported value was obtained. Guides of this type should find use as the active components in InP switches and interferometers.     

InAsxP1?x/InP photodiodes prepared by molecular-beam epitaxy

Photodiodes have been made in epitaxial layers of InAsxP1?x grown by molecular-beam epitaxy on InP substrates The As-P ratio of this material system can be adjusted to produce photodetectors for the 2?3 ?m-wavelength region. Initial devices exhibit cutoff wavelengths as long as 2 ?m.     

Strain distribution in InP grown on patterned Si: Direct visualization by cathodoluminescence wavelength imaging

InP has been grown on patterned Si substrates using a low temperature metalorganic chemical vapor deposition process which insures compatibility with integrated circuit technology. Two different patterns are investigated: wet chemically etched V-grooves and SiO₂-masked dry etched grooves. Reduction of feature size leads to drastic defect reduction and quantum efficiencies up to those of homoepitaxially grown InP. Strain relaxation and quantum efficiency are directly visualized by cathololuminescence wavelength imaging. On (001)-and {111}-facets of V-grooves distinct relaxation of the tensile thermally induced strain are found. Surprisingly, in the bottom of V-grooves, close to or even at the InP/Si interface, a high quantum efficiency is found with a recombination time constant typical for thick InP layers of high crystallographic quality.     

The behavior of unintentional impurities in Ga0.47 In0.53As grown by MBE

A number of factors contribute to the high n-type background carrier concentration (high 10¹⁵ to low 10¹⁶ cm⁻³) measured in MBE Ga_0.47In_0.53As lattice-matched to InP. The results of this study indicate that the outdiffusion of impurities from InP substrates into GalnAs epitaxial layers can account for as much as two-thirds of the background carrier concentration and can reduce mobilities by as much as 40%. These impurities and/or defects can be gettered at the surfaces of the InP by heat treatment and then removed by polishing. The GalnAs epitaxial layers grown on the heat-treated substrates have significantly improved electrical properties. Hall and SIMS measurements indicate that both donors and acceptors outdiffuse into the epitaxial layers during growth resulting in heavily compensated layers with reduced mobilities. The dominant donor species was identified by SIMS as Si, and the dominant acceptors as Fe, Cr and Mn.     

InP衬底上Ga_(0.47)In_(0.53)As/InP液相外延生长

用液相外廷获得了与InP晶格匹配的Ga_(0.47),In_(0.53)As单晶外延层.本文叙述在(100)和(111)InP衬底上Ga_(0.47)In_(0.53)As/InP液相外延生长方法.用常规滑动舟工艺生长的这种外延层,其表面光亮,Ga的组分x=0.46～0.48,晶格失配率小于2.77×10~(-4),禁带宽度E_g=0.74～0.75eV.使用这种Ga_(0.47)In_(0.53)As/InP/InP(衬底)材料研制的长波长光电探测器,在波长为0.9～1.7μm范围内测出了光谱响应曲线,在1.55μm处呈现峰值.     

Solution-grown epitaxial InP for high-efficiency circuit-controlled microwave oscillators

High-purity epitaxial InP has been prepared by solution growth with free-donor concentrations of 2×1015 cm?3 and liquid-nitrogen mobility of 49 000 cm2/Vs. The growth technique is described and the electrical properties of the layers are given. The microwave characteristics of diodes made on this material are described, and these, together with experiments on specially constructed diodes, suggest that a circuit-controlled bulk negative-resistance mode can be set up in this material. Devices have been produced which give up to 16% efficiency when operated in coaxial circuits at X band.     

InGaAsP quaternary alloys: Composition,refractive index and lattice mismatch

Extrapolation schemes for the calculation of InGaAsP material parameters are described. Experimental data on alloy composition, bandgap, lattice parameter and refractive index are presented and compared with calculated values. Refractive index steps between InGaAsP and InP were found to vary significantly with lattice mismatch. Errors in alloy composition of mismatched epitaxial layers, deduced from bandgap and lattice parameter measurements, can be caused by a tetragonal distortion of the crystal lattice.     

Characterization of (111) Gaas and (111) InP substrates and homoepitaxial layers by divergent x-ray beam diffraction

The back-reflection diffraction of a divergent x-ray beam has been studied for the characterization of (111) GaAs and (111) InP substrates and homoepitaxial layers with different states of surface perfection. Diffraction conditions for generating back-reflection pseudo-Kossel patterns from (111) GaAs and (111) InP are presented. Mechanical polishing was observed to produce x-ray diffraction line broadening. Uneven line broadening was found to be produced by an inhomogeneous distribution of dislocations. The diffraction angles for pseudo-Kossel lines were influenced by subgrain tilting in epitaxial, LPE-grown layers. A close relationship between diffraction line profiles and surface morphology of the epitaxial layer was demonstrated with interference-contrast optical microscopy.     

Fabrication of an NpM GaInAs/InP bipolar transistor by a two-step epitaxial process

A two-step liquid-phase-epitaxial process has been used to fabricate widegap-emitter Schottky collector transistors. After the growth of the first two epitaxial layers the sample has been structured and then overgrown in a second run. In that way a pn homojunction in the widegap material (InP) underneath the extrinsic base-emitter region and a pn heterojunction under the collector have been formed. First transistors fabricated show a current gain of 10 in the common-emitter configuration.     

Self-organizing nanoheterostructures in InGaAsP solid solutions

This paper discusses the photoluminescence and x-ray microstructural properties of epitaxial layers of solid solutions of InGaAsP isoperiodic with InP (100) and GaAs (100) substrates, obtained in the region of immiscibility and spinodal decay. It shows that there is good agreement of the experimental results with the theoretical model of spinodal decay. The boundaries of the region in which two solid phases of different composition exist in epitaxial layers of solid solutions of InGaAsP isoperiodic with the InP and GaAs substrates are determined. A periodic nanoheterostructure is obtained in an epitaxial layer of InGaAsP solid solutions with a repetition period of 650±30 Å in two mutually perpendicular directions.     

Grafted GaAlAs rib waveguides on an InP substrate

Rib waveguides were fabricated on a 1.4 mu m thick GaAlAs epilayer granted on the surface of a semi-insulating InP substrate by epitaxial lift-off. Single-mode waveguides with propagation losses (<7 dB/cm) lower than heteroepitaxially grown counterparts have been achieved. TEM analysis on the GaAlAs/InP interface indicates surface scattering as one of the main loss mechanisms.<>     

Enhanced mobility PMOSFETs using tensile-strained Si1-yCy layers

We demonstrate for the first time that carbon incorporation in Si epitaxial layers may be an alternative method to deposit enhanced mobility tensile-strained Si MOSFET channel layers directly on a silicon substrate, thereby eliminating the need to deposit a thick relaxed SiGe buffer layer, from which dislocations and other defects can propagate to the channel region. The fabrication and electrical properties of PMOSFETs with Si_1-yC_y alloy channel layers are reported in this paper for the first time. It is found that small amounts of C in Si films can produce high quality epitaxial material. PMOSFETs fabricated on these layers demonstrate enhanced hole mobility over that of control Si     

Atomic layer epitaxy of InP

In this work we will discuss the growth conditions for ALE of InP. Growth experiments were carried out in a LP-MOCVD system with a fast switch gas manifold. InP layers were deposited by pulsing TMIn and PH₃, using Argon as carrier gas. A self limiting growth rate at 1 ML/cycle has been obtained with a substrate temperature as low as 320-360° C. InP epitaxial layers were grown on GaAs and InP substrates, and on GaInAs(P) layers previously deposited by conventional MOCVD. Selective area epitaxy on InP using a Si₃N₄ mask was also demonstrated. Results of this study are very encouraging for hybrid MOCVD/ALE growth of In-based compounds.     

GaAs on Si as a substrate for microwave and millimeter-wavemonolithic integration

The authors calculated the effective dielectric constant, characteristic impedance, and dielectric loss of a shielded microstrip line manufacture on namely GaAs, Si, and GaAs/Si. Dielectronic loss versus frequency for the GaAs and Si substrates are shown. The same parameters for GaAs/Si substrate were plotted for two different resistivities of the GaAs overlay material, and for each of three different GaAs overlayer thicknesses. The measurements covered the 10-100-GHz frequency range. Depending on the thickness, results show that high-resistivity GaAs epitaxial layers on Si substrates having moderate resistivities reduce the dielectric loss     

InP epitaxy with a new metalorganic compound

A new metal-organic compound, a trimethyl-indium trimethyl-phosphine adduct has been used for the growth of InP epitaxial layers. The formation of unwanted polymer products during epitaxial growth could be avoided in this way. Epitaxial layers of good quality (ND ? NA?1016?1017 cm?3 were grown at a rate of 0.8 ?m/h.     

InGaAs Gunn oscillators

Measurements with Gunn oscillators made from epitaxial layers of the ternary InGaAs lattice matched to InP are reported. Operation in the domain mode was chosen. First results are given demonstrating the potential of this alloy for high-efficiency Gunn devices.