Papers by Keyword: Gallium Arsenide

Abstract: In this study, we investigated the effect of the post-etch cleaning of GaAs surfaces. We found that a plasma damage layer was formed on GaAs surfaces by dry etching, and an As-rich layer remained after post-etch cleaning. The As rich layer needs to be removed because it is replaced by micron-sized particles when stored in an air. We also found that a pure GaAs surface can be obtained by performing additional cleaning consisting of oxide formation and removal.

Abstract: We report our experiments based on the interfaces of a 5-period superlattice, containing GaAsP(3Å)/GaAs (190Å) heterostructures grown by molecular beam epitaxy (MBE). The atomic arrangement at the interfaces of GaAsP/GaAs is investigated using high resolution transmission electron microscopy (HRTEM). Our results indicate that the superlattice was grown coherently with strained layers. We propose that the atomic arrangement at the interface is GaP, assuming that phosphorus incorporation occurs primarily via substitution due to desorption of arsenic at the surface for substrate temperatures above 500°C. The incorporation of phosphorus has been investigated using fast Fourier transform (FFT) patterns and shows a form of strain distribution near the heterointerface. The FFT patterns of the superlattice reveal that strain distributes mostly near the interface and gradually decreases along the direction of growth. Phosphorus diffused into a GaAs layer changes the lattice constant in the growth direction, which reduces strain in the superlattice.

Abstract: Self-assembled 1-eicosanethiolate layers were deposited on the oxide-free (100) crystal planes of GaAs, In_0.53Ga_0.47As, and InSb to protect the surfaces. The layer prevented re-oxidation in air for 30 min on GaAs but only 8 min on In_0.53Ga_0.47As based on the O 1s x-ray photoelectron spectroscopy state. The layer protected InSb from reoxidation for only 4 min based on the O Auger state. Well-ordered monolayers formed on GaAs and In_0.53Ga_0.47As based on transmission Fourier transform infrared (FTIR) spectroscopy. A partially ordered layer was formed on InSb based on attenuated total reflection FTIR. The increased reoxidation rate of InGaAs and InSb is due to the larger lattice parameter of these surfaces and their In content, which forms weaker bonds to S, Ga, and Sb compared to Ga bonding to As and S.

Abstract: Oxidation of a GaAs surface was performed with liquid H₂O₂, gaseous O₂ and O₃ in order to identify the best solution for digital etching. The oxide layer formed with H₂O₂ is Garich and exhibits surface roughening which can be understood by oxide hydrolysis/condensation model. Roughening makes aqueous H₂O₂ irrelevant as an oxidizing agent for repeated oxidation steps. On the other hand, a smooth oxide layer can be obtained with gaseous O₂ and O₃. Thickness of the formed oxide layer is controlled by time exposure to the oxidizing agent. The nature of the oxide was analyzed by XRay Photo-electron Spectroscopy and is also timedependent.

Abstract: Using computer programs Elmer FEM Solver for calculating electric fields and Geant4 for the passage simulation of particles through matter, calculations of charge collection efficiency for nuclear radiation matrix detector based on GaAs p-i-n diodes with different distances between pixels 110 microns and 50 microns were made. Based on data obtained detector structure optimization solution, which improves energy resolution, is proposed.

Abstract: Gallium Arsenide (GaAs) based solar cell which have nearly ideal direct bandgap of 1.43eV hold the highest single junction solar cell efficiency. GaAs solar cell without Anti-Reflective Coating (ARC) layer was studied and shows the efficiency ranges between 8% to 15%, followed by GaAs solar cell with efficiency ranges between 20% to 25% with ARC layer. The substrate thickness for both GaAs solar cell was varied from 0.1μm to 1.0μm. Increased of P-type substrate thickness shows a small variation in efficiency with parabolic shape, while increased of N-type substrate thicknesss increased the efficiency between 21% to 25% for single layer GaAs with ARC thickness. Besides that, increased of P-type doping concentration from 1×10¹⁸cm^-3 to 1×10¹⁹cm^-3 and fixed N-type doping will decreased the efficiency. However increased the N-type doping concentration from 1×10¹⁷cm^-3 to 1×10¹⁸cm^-3 and fixed the P-type doping will increased the efficiency. The thickness of ARC layer on GaAs solar cell was studied and shows that highest efficiency achieved at narrow thickness of ARC.

Abstract: Normal 0 false false false RU X-NONE X-NONE The combination of methods of voltammetry, Raman spectroscopy, and X-ray reflectometry for the first time has been applied for the more comprehensive investigation of interfacial boundaries of GaAs, i.e. determination of phase distribution and thickness of the phase layers. The conditions for the formation of elemental arsenic on a GaAs surface in the process of selective dissolution are discussed. The stability of interfacial boundaries in air has also been studied. The investigations have shown that air storage lead to the oxidation of formed As⁰ and reorganization of GaAs interfacial boundary accompanied by the formation of Ga₂O₃ and As⁰ as a result of a reaction between As₂O₃ and GaAs. The results on interfacial boundaries composition were found to be correlated with the theoretical data. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;}

Abstract: III-V semiconductor compounds are increasingly studied for their interesting properties in the fields of microelectronics, optoelectronics, infrared detectors or solar cells. Firstly, they are promising candidates to replace silicon as a channel material. As CMOS scales beyond the 22 nm node it is widely expected that new higher mobility channel materials such as In_xGa_1-xAs will have to be introduced [1]. On the other hand, III-V materials have a direct bandgap making them useful for optoelectronic devices or high-efficiency multijunction photovoltaic cells. For these applications InP, GaAs and their alloys as In_xGa_1-xAs and Ga_xIn_1-xP are investigated [2]. Depending on the targeted applications, several possible integration routes of III-V components could be considered: from 100 mm III-V substrates to III-V epitaxial layers grown on 300 mm silicon wafers as well as a few square centimetres chips bonded on 200 or 300 mm carrier wafers for photonics applications. In all cases, the manufacturing of devices requires a multitude of wet chemical steps including selective etching steps (from a few nanometres up to several microns) and cleaning steps (metallic or particles contamination removal).

Abstract: Incorporating substrates with higher charge mobilities than Si and Ge in metal-oxide-semiconductor field-effect transistors (MOSFETs) would extend the scaling of this device architecture. III-V semiconductors are candidates, and etching and passivation processes are needed that are selective and yield smooth surfaces. The (100) face of III-V compounds contains both electron-deficient group III (Ga, In) atoms and electron-rich group V (P, As, Sb) atoms. Etching InP(100) in a mixture of HCl and H₂O₂ chlorinates the In (group III) atom forming a soluble product [1,2], yet the P (group V) atom is more reactive and is depleted from the surface [3]. α-Hydroxy acids (lactic, citric, malic, and tartaric) have been shown to bind to the group III atom [3] and could promote more uniform etching. This paper compares the surface chemistry of GaAs and InAs after etching in HCl and H₂O₂ mixtures with and without tartaric acid.

Abstract: Three-dimensional molecular dynamics (3D MD) simulation was carried out to investigate the deformation of single crystal gallium arsenide (GaAs) during nanoindentation. Tersoff potential was used to simulate the atomistic interaction under an extremely low load of indentation. The coordination number and atomic displacement were studied and the cross-sectional profiles of the simulated indent were examined. The simulation results revealed that the lattice deformation of GaAs was influenced by polarity, showing distinct patterns on different crystalline planes. Slip band and dislocation were found to be the dominant deformation phenomena.