Thin InAs Layer Research Articles

Influence of thin protective InAs layers on the optical quality of AlGaAs and quantum wells

Influence of a thin protective but subsequently evaporated InAs layer on the regrowth of AlGaAs has been studied. It was found that although most of the InAs could be evaporated by thermal desorption, some would react with Al0.36Ga0.64As to form InAlGaAs. These InAlGaAs islands act as potential wells for carrier recombination and dominate the photoluminescence spectrum. Transmission electron microscopy photographs show that dislocations are formed near the islands. These defects are caused by lattice mismatch between AlGaAs and InAlGaAs. These islands and defects strongly affect the optical quality of surrounding Al0.36Ga0.64As and quantum wells.

Improved InAlAs/InGaAs HEMT characteristics by inserting an InAs layer into the InGaAs channel

An InAlAs/InGaAs HEMT with a thin InAs layer inserted into the InGaAs channel is proposed and its electron transport properties and device performances have been investigated. By optimizing the thickness and the exact point of insertion in the InAs layer, the mobility and electron velocity at 300 K have been increased by 30% and 15%, respectively, compared to the conventional heterostructure. In addition, a maximum intrinsic transconductance of 970 mS/mm and a maximum current gain cutoff frequency of 58.1 GHz have been attained by a 0.6 mu m-gate-length device.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-frequency performance for sub-0.1 μm gate InAs-inserted-channel InAlAs/InGaAs HEMT

The authors examine the high-frequency performance of a sub-0.1 mu m gate InAlAs/InGaAs HEMT with a thin InAs layer inserted into the InGaAs channel. The transconductance is 2.1 S/mm and the current-gain cutoff frequency is 264 GHz using a 0.08 mu m-long gate.

Observation of photoluminescence from InAs surface quantum wells grown on InP(100) by molecular beam epitaxy

Photoluminescence (PL) measurements are presented for thin epitaxial layers of InAs, 2.5 Å&amp;lt;d &amp;lt;36 Å, grown on InP(100) by molecular beam epitaxy. The combination of efficient carrier capture and PL redshift with increasing InAs thickness clearly indicate the formation of InAs quantum wells on the InP surface. Data are also presented for InAs/InP structures capped with strained layers of either GaAs or In0.5 Al0.5 As. Since radiative recombination within the InAs layers can be distinguished from PL arising from both bulk and surface defects, this system allows us to monitor the quality of both the InAs/InP and InAs/air interfaces via their influence on the InAs quantum well luminescence.

Picosecond saturable absorption measurements on thin film single-crystal InAs layers grown by MBE

The linear and nonlinear optical properties of high-quality single-crystal thin (3.3 mu m) MBE films of InAs on GaAs substrates are studied using the lambda =2.94 mu m output of a mode-locked Er3+ laser. The onset of absorption saturation occurs at pulse energy densities of approximately=100 mu J cm-2, and a dynamic Moss-Burstein effect model gives a good quantitative explanation of the experimental data. Very rapid adsorption recovery times ( approximately=150 ps) suggest that interfacial recombination is the dominant relaxation mechanism, and indicate the potential for the use of these novel semiconductor heterostructures as fast passive optical shutters for mode-locking and Q-switching applications in the mid-infrared.

Studies of TMGa adsorption on thin GaAs and InAs (001) layers

Adsorption of TMGa on thin overlayers of GaAs/AlAs and InAs/InP structures is investigated. The number of Ga monolayers is determined precisely from such structures for various TMGa exposures. Slower reaction rates for TMGa on Ga-stabilized surfaces compared to As-stabilized surfaces result in the self limiting mechanism of atomic layer epitaxy (ALE) using TMGa. On the other hand, adsorption of TMGa on InAs (001) surfaces involves more than the very top layer atoms. Exchange of In/Ga is observed with In atoms floating on top of the surface, which enhances Ga atom formation and impedes saturation as in the case of GaAs surfaces.

Electrical properties of InAs epilayers grown by molecular beam epitaxy on Si substrates

InAs epitaxial films have been grown by molecular beam epitaxy on high-resistivity Si (20 Ω cm) substrates for the first time, and transport properties were investigated by Hall effect measurements down to 10 K. The electron mobilities peak at 75 K with a value of 4.5×104 cm2/(V s) in 6.7-μm-thick (n=2.6×1015 cm−3 ) unintentionally doped layers. It is shown that the temperature dependence of the Hall mobility can be explained by a combined ionized impurity-polar optical phonon scattering model in the thin InAs layers. Despite the existence of a large lattice mismatch, the results are indicative of a high quality material.

Room temperature operation of unipolar hot electron transistors

In this paper we discuss the kinematic and dynamical constrains involved in the design of useful unipolar hot electron transistors and we demonstrate room temperature operation of a double heterojunction hot electron transistor with a two-dimensional electron gas forming the base region. Our test structure has the narrowest ever reported base width at a mere 100Å and is the first such transistor to show current gain in excess of 10 at room temperature. The device uses an indirect, wide band gap AlSb 0.92As 0.08 emitter and the transistor base is a thin InAs layer.

Unipolar Hot Electron Transistors

We discuss kinematic and dynamical constrains in design of useful unipolar hot electron transistors. In addition, we demonstrate room temperature operation of a double heterojunction hot electron transistor with a two-dimensional electron gas forming the base region. Our test structure has the narrowest ever reported base width at a mere 100 Å and is the first such transistor to show current gain in excess of 10 at room temperature. The device uses an indirect, wide bandgap AlSb0.92As0.08 emitter and the transistor base is a thin InAs layer.

Role of thin multiquantum wells in controlling intrinsic interface quality in molecular beam epitaxially grown heterostructures

A model based on Monte Carlo simulations and theory of statistical fluctuations is presented for molecular beam epitaxy growth of III-V semiconductors. It is shown that under normally employed growth conditions, cation surface migration controls the surface (interface) quality. The surface of a growing film gets rougher with increasing thickness of the film due to statistical fluctuations in the cation flux and limited cation migration. An important outcome of this theory is that the substrate temperature for high quality semiconductor surfaces and interfaces can be substantially reduced if growth is punctuated by thin layers (5–10 monolayers) of a low melting temperature semiconductor. Potential use of thin layers of InAs and GaAs for low-temperature growth of GaAs and AlGaAs, respectively, is discussed.

Investigations of trace analysis of AIIIBV semiconductor microsamples by atomic spectroscopy—VII Investigation of trace and thin-layer analysis of doping elements (Ag, Au, Bi, Cd, Sn, Tl) in InAs by atomic-absorption with electrothermal evaporation

Etching procedures for separation of thin layers of InAs (up to 1.4 mum thick) have been developed and optimized. A solid-state microtome has been used for cutting layers thicker than 1mum. AAS/ETA methods for determination of traces of Ag, Au, Bi, Cd, Sn, and Tl have been developed. The matrix interferences of nitric add, hydrobromic acid, and As(3+) or In(3+) in nitric or hydrobromic acid have been studied. The main causes of the matrix interference are the formation of diatomic molecules between the trace and matrix components, and the effect of the evaporation processes. By use of the platform technique with special platforms some matrix interferences could be minimized. For the determination of traces of Sn, matrix modification with Ni(NO(3))(2) as additive gave the best analytical values. For the trace determination of Au, separation of In from Au by evaporation of InBr(3) from 0.6M HBR medium in the AAS ashing phase was developed. The detection limits are in the 10(16) atoms/cm(3) region for layers of 1 mum thickness and surface area 1 cm(2).

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Chemical composition of InP substrate surface heattreated under As molecular beam exposure in an ultrahigh vacuum chamber was studied with ESCA, and surface reconstruction of the substrate was examined by in-situ electron diffraction. The InP substrate heated under the exposure of As molecular beam has mirror surface up to 590°C while the surface of InP heated above 400°C in vacuum is roughened. The ESCA study shows that thin InAs layer (thickness<20A) is formed on the surface of InP heated above 500°C under the exposure of As. The electron diffraction study indicates that the InP is cleaned at about 500°C in As pressures of 10-7-10-5 Torr. The InP surface is prevented from thermally decomposing by the coverage of the InAs layer, which may be formed through the following process :2InPO4+As4→2InAs+P2O5↑+As2O3↑.

Hybrid cyclotron-intersubband resonance in thin InAs layers confined between GaSb

In a heterostructure of InAs confined between GaSb, measurements of far infrared transmission as a function of the magnetic field and its orientation demonstrate the formation of hybrid subbands due to electric and magnetic quantization. The observed energies of resonant transitions with the magnetic field parallel to the layer plane are in quantitative agreement with those calculated theoretically.

Studies by cross-sectional transmission electron microscope of InAs grown by molecular beam epitaxy on GaAs substrates

We have used the cross-sectional transmission electron microscope to study InAs grown by molecular beam epitaxy. For the InAs films directly grown on GaAs, the dislocation density at the InAs-GaAs interface is several orders of magnitude higher than that in the bulk films. Those grown by the step grading technique show strong interactions among dislocations at the interfaces, and a much reduced dislocation density in the thin InAs layers.

Thin InAs epitaxial layers grown on (100) GaAs substrates by molecular beam deposition

Thin heteroepitaxial layers of InAs have been grown on (100) GaAs substrates and buffer layers by molecular beam deposition in a UHV chamber. Smooth epitaxial layers as indicated by in situ MEED patterns have been obtained at substrate temperatures in the range 330–530 °C and SEM micrographs and electron channeling patterns taken ex situ have confirmed these properties. MEED observations also indicated that epitaxial growth can be obtained at considerably lower deposition temperatures. InAs films, 0.5–2.0 μm thick, grown between 330 and 530 °C had bulklike electrical properties with residual n-type carrier concentrations in the range 5×1016 to 1×1018 cm−3, the lowest values occurring for depositions at 530 °C.