Magnesium doping of (Al,Ga)As in metalorganic chemical vapor deposition

Abstract

Magnesium doping of AlxGa1−xAs in metalorganic chemical vapor deposition and the properties of the grown layer have been investigated. Bis-cyclopentadienylmagnesium, CP2Mg, was used as a precursor of Mg. The hole concentration increased linearly from 3.5×1016 to 1×1019 cm−3 when the ratio of CP2Mg to trimethylgallium was increased. The carrier concentration increased with the increase of Al concentration, decreased with the increase of growth temperature, and was independent of the ratio of arsine to column III elements, V/III. The photoluminescence (PL) intensity increased when the growth temperature was increased and/or the V/III ratio was increased. The intensity of a deep PL band associated with near band-edge emission, usually seen in the low-temperature PL spectra of Zn-doped (Al,Ga)As, was smaller than that in Zn-doped (Al,Ga)As. The activation energy of the Mg acceptor deduced from the temperature dependence of the carrier concentration was smaller than that of the Zn acceptor.