New photoluminescence lines in Vanadium doped GaAs grown by MOVPE
We examined the electrical and optical properties of vanadium-doped GaAs grown by metalorganic vapour phase epitaxy using vanadium tetrachloride (VCl4) as a novel dopant source. Samples with various vanadium incorporations were investigated. All samples were n type. The electron concentration dependence on the VCl4 flow rate was established. At 15 K, by comparison with undoped layers grown in the same conditions, photoluminescence spectra of V-doped exhibited three new emission bands: at 1.41, 1 and 0.72 eV. The 1 and 0.72 eV band emissions were attributed to V 2þ and V 3þ intracenter emission, while the 1.41 eV band was suggested to be a donor-bound transition. The identity of the donor is tentatively attributed to a donor complex that associates vanadium to an arsenic vacancy. From Hall effect as function of temperature, the donor ionisation energy was estimated to be about 102 ^ 5 meV. q 2003 Elsevier Science Ltd. All rights reserved.
Statistical analysis of vanadium in gallium arsenide
The electrical properties of vanadium‐doped GaAs grown by metalorganic vapor phase epitaxy were studied between 77 and 300 K. The temperature‐dependent electron concentration, for different partial pressures of VCl4, was simulated using the charge balance equation. A calculation model was used with parameters (energy levels and V concentration) derived from photoluminescence, deep‐level transient spectroscopy and secondary ion mass spectroscopy measurements. The magnitude and the temperature dependence of neutral and ionized V concentrations were determined. It is shown that most of the V concentration is inactive. This is in good agreement with some previous reports in the literature. The detailed analysis including the probability of V donor incorporation in GaAs was then extended to explain the evolution of electron concentration as a function of partial pressure of VCl4. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of semi-insulating epitaxial gallium arsenide by chromium doping in the metal-alkyl+hydride system
Abstract Gallium arsenide grown epitaxially by the metal-alkyl+hydride vapour system can be controllably doped with chromium using hexacarbonyl chromium. The concentration of chromium incorporated and the saturation level of solubility have been determined. Semi-insulating epitaxial gallium arsenide can be readily produced, and its use as a buffer layer in MESFET's is demonstrated.