Shallow acceptor and hydrogen impurity in p-type arsenic-doped ZnMgO films grown by radio frequency magnetron sputtering

Arsenic-doped ZnMgO films were fabricated on SiO2 by the radio frequency magnetron sputtering technique at different substrate temperatures during growth. The yielded films were characterized by room temperature Hall measurement, x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, secondary ion mass spectroscopy, nuclear reaction analysis and low-temperature photoluminescence. As-doped samples grown at low substrate temperature (350 °C) were n-type conducting (n ~ 1018 cm−3), with evidence showing that the hydrogen impurity was an important shallow donor associated with the observed n-type conduction. Conversion of n-type to p-type conduction being observed at the substrate temperature of ~400 °C was associated with the formation of the AsZn(VZn)2 shallow acceptor complex and the drastic reduction of the hydrogen content.