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 degrees C) were n-type conducting (n similar to 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 similar to 400 degrees C was associated with the formation of the As_Zn(V_Zn)₂ shallow acceptor complex and the drastic reduction of the hydrogen content.