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.
Theoretical investigation of the electrical and optical activity of vanadium in GaAs.
%e study the excitation and ionization processes at the isolated substitutional vanadium impurity in GaAs. The electronic structure is solved through the spin-restricted version of the multiplescattering Xa method to obtain the relevant mean-field energies, and correlation effects are evaluated through the Fazzio-Caldas-Zunger multiplet approach. The similar systems GaP:V, InP:V are also investigated. Our results for GaAs:V point to the occurrence of an acceptor level at -E,—0. 16 eV, the donor level appearing very close to or within the valence band. The V-related midgap acceptor should then be related to some complex defect involving vanadium. We also suggest that V2+ in these compounds is present in the low-spin ground state 2E.
Chromium-doped GaAs vapor phase epitaxy
Abstract Semi-insulating chromium-doped GaAs epitaxial layers were grown using a Ga/AsCl 3 /H 2 system with CrO 2 Cl 2 as a dopant. The resistivity was of the order of 10 8 ohm cm. It was shown that chromium acted as deep acceptor with an activation energy of 0.57 eV and could compensate shallow donors with a concentration of about 10 16 cm -3 . The n-type layer doped with sulfur whose carrier concentration was 1.2 x 10 17 cm -3 with a mobility of 5200 cm 2 /V sec was successively grown on the semi-insulating epitaxial layer in one run. The boundary layer was abrupt and excellent for FET application.