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

We report on intrinsic p-type ZnO thin films by plasma-assisted metal-organic chemical vapor deposition. The optimal results give a resistivity of 12.7 Omega cm, a Hall mobility of 2.6 cm(2)/V s, and a hole concentration of 1.88 x 10(17) cm(-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 270 meV 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.status: publishe