p -type behavior in nominally undoped ZnO thin films by oxygen plasma growth

Abstract

We report on intrinsic p-type ZnO thin films by plasma-assisted metal-organic chemical vapor deposition. The optimal results give a resistivity of 12.7Ωcm, a Hall mobility of 2.6cm2∕Vs, and a hole concentration of 1.88×1017cm−3. The oxygen concentration is increased in the intrinsic p-type ZnO, compared with the n-type layer. Two acceptor states, with the energy levels located at 160 and 270meV above the valence band maximum, are identified by temperature-dependent photoluminescence. The origin of intrinsic p-type behavior has been ascribed to the formation of zinc vacancy and some complex acceptor center.