Role of vanadium in organometallic vapor phase epitaxy grown GaAs

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Abstract
The electrical and photoluminescent properties of vanadium incorporated into GaAs epitaxial layers from a VO(OC2H5)3 source during organometallic vapor phase epitaxy were examined. The vanadium concentration in the GaAs was controllably varied from 1016 to 1018 atoms cm−3. Deep level transient spectroscopy showed the presence of an electron trap at Ec−0.15 eV which increased in concentration with vanadium content of the epitaxial layers. A maximum value of 8×1015 cm−3 for this trap was obtained. There were no midgap electron traps associated with vanadium. In intentionally Si-doped epitaxial layers, co-doping with vanadium was observed to have no effect in reducing the carrier density when the Si concentration was ≥4×1016 cm−3. The net carrier concentration profiles resulting from 29Si implantation into GaAs containing 1018 cm−3 of total V had sharper tails than for similar implantation into undoped material, indicating the presence of less than 1016 cm−3 V-related acceptors. Photoluminescent spectra exhibited the characteristic V+3 intracenter emission at 0.65–0.75 eV. No other deep level photoluminescence was detected. For a V concentration of 1016 cm−3 only 2.5×1013 cm−3 was electrically active. Over the entire V concentration investigated this impurity was predominantly (≥99%) inactive.