Papers by Keyword: GaAs

Abstract: The GaAs nanowires are grown on Si (111) substrates by Ga-assisted molecular beam epitaxy growth technique. The effect of SiO₂ thickness on the structural properties of GaAs nanowires is investigated by Scanning Electron Microscope (SEM). The nucleation of GaAs nanowires related to the presence of a SiO₂ layer previously coated on Si substrate. The results show that the density, length, and diameter of GaAs nanowires strongly depend on the oxidation time (or SiO₂ thickness).

Abstract: We report on the study on effect of Ga pre-deposition rate on GaAs nanowires grown by self-assisted vapor-liquid-solid (VLS) method. Ga droplets were initially deposited on the surface of Si(111) substrates covered with thin layer of SiO₂. The nanowires were grown by molecular beam epitaxy (MBE). Dependency of structural of nanowires on Ga pre-deposition rate is investigated by Scanning Electron Microscope (SEM), Energy-dispersive X-ray spectroscopy (EDX), and X-ray Diffraction Analysis (XRD). The experimental results show that the different in Ga pre-deposition rate significantly affect the surface morphology of samples. Growth rate and the density of nanowires strongly depends on the Ga pre-deposition rate.

Abstract: In this paper, Be-doped GaAs were grown by molecular beam epitaxy (MBE), by changing Be resource temperature, we obtained different doping concentration GaAs samples. The morphologies and electrics properties of the samples were investigated by AFM and Hall measurement. Especially, in low temperature and temperature dependent PL spectra, the Be acceptor related emission were recognized, with the doping concentration increasing, the Be acceptor related emission enhanced too.

Abstract: The optical and chemical properties of gallium arsenide (GaAs) surfaces treated by ammonium sulfide ((NH₄)₂S) treatments were studied via low-temperature photoluminescence (PL). From the PL mapping and Atomic Force Microscope (AFM) results, the treatment process by (NH₄)₂S is quite effective to remove the oxide layer of GaAs.The PL intensity of (NH₄)₂S-passivated sample was higher than the untreated sample, and the homogeneity of passivated surface was much better. This strategy provides superior promising passivation method for III-V compound semiconductor material in high-speed and optoelectronic device applications.

Abstract: The authors have been investigated structural, magnetic and electrical transport properties for CFAS/n-GaAs junctions. From cross sectional TEM image, RHEED and XRD patternz of thin CFAS films, CFAS films found to be grown epitaxially on GaAs, and shown L2₁-ordered structure for the films with substrate temperature (T_CFAS) of 300°C and 400°C. It is hard to find some additional phase around the interface between CFAS and GaAs. Magnetic moment (and magnetic anisotropy energy) of CFAS increased (and decreased) with increasing T_CFAS up to 300°C and decreased (and increased) at T_CFAS of 400°C, respectively. The asymmetry of current (J)-voltage (V) curve for the junction with T_CFAS =300°C was found to be larger than those for other junctions. It was found there is the relation between T_CFAS dependence of spin signal obtained by three terminal Hanle or four terminal non-local measurement and that of magnetic moment, magnetic anisotropy field or asymmetry of J-V curve.

Abstract: Two 81-96 GHz frequency triplers, one balanced and one single device, are implemented using a 0.10 μm GaAs pHEMT process. The EM simulation results show that the triplers perform a best conversion gain of -6.8 and -4.7 dB for the balanced and the single device, respectively. The conversion gain of the balanced tripler operating from 81 to 96 GHz is above -9.6 dB at 3dBm input power. The conversion gain of the single device operating from 81 to 96 GHz is above -8 dB at -0.5dBm input power. The fundamental and second harmonic suppression are as high as 30 dB over the whole operating frequency (81-96 GHz) for both circuits.

Abstract: In this work we carried out electrical characterization of n-GaAs implanted at 300 K with high energy (100 MeV) ²⁸Si and ¹²⁰Sn ions to a fluence of 1x10¹⁸ ions/m² using current–voltage (I-V) measurements. The as implanted samples and samples annealed in the temperature range 373-1123 K have been investigated. Resistance of the samples obtained from I-V curves recorded over the temperature range 110K-270K indicate that the samples implanted with ²⁸Si and annealed up to 623 K and the samples implanted with ¹²⁰Sn and annealed up to 723K shows tunnel assisted hoping conduction mechanism. In the other hand, ²⁸Si implanted samples annealed to 723K and 823K and ¹²⁰Sn implanted samples annealed to 823K and 923K the electrical conduction mechanism is dominated by thermal hoping between closed defect states.

Abstract: Indium Antimonide (InSb) has the greater electron mobility and saturation velocity of any semiconductor. Also InSb detectors are sensitive between 1–5 μm wavelengths and it belongs to III-V [13] component. In this paper we compare the InSb with some other major components like Indium Phosphide (InP) and Gallium Arsenide (GaAs) which are also from same III-V group. The analysis was made using the simulation tool TCAD and using the properties and band structure of those materials we compare InSb with InP and GaAs. The results we proposed shows that InSb is best for ultra high speed and very low power applications.

Abstract: We have studied the optical properties of GaAs and Al_xGa_1-xAs thin films using low-temperature photoluminescence and Fourier transform infrared spectroscopy. The GaAs and its alloys were grown by MOCVD using solid arsenic instead of arsine, as the arsenic precursor. The gallium and aluminium precursors were trimethylgallium (TMGa) and trimethylaluminium (TMAl), respectively. Some difficulties for growing Al_xGa_1-xAs by solid-arsenic-based MOCVD system are the composition homogeneity of the layers and the oxygen and carbon incorporation during the growth process. The composition homogeneity of the films was evaluated by low-temperature photoluminescence. Infrared measurements on the samples allowed the identification of the residual impurities, which are carbon-substitutional, Ga₂O_3, molecular oxygen, humidity and two unidentified impurities. Samples grown at temperatures lower than 750°C were highly resistive, independently of the ratio V/III used; the samples grown at higher temperatures were n-type, as it was proved by Hall effect measurements.

Abstract: The current industry needs for new results require current capabilities of computer technology can solve problems on a whole new level. This article briefly describes the algorithms for obtaining the structures and the appearance of discontinuities in the growth of crystals.