Homoepitaxy of ZnO: From the substrates to doping

Abstract

We report on the homoepitaxial growth of ZnO thin films by chemical vapor deposition techniques. The preparation of the ZnO substrates after mechanical polishing employed a high temperature annealing step which produced atomically flat surfaces and removed all of the surface and subsurface damage. Two dimensional epitaxial growth was achieved without an additional buffer layer. The substrate had a rocking curve with a full width at half maximum of 27″ which can be compared with that of the film of 17″. The films had superior band edge luminescence as compared with the substrate for which the green luminescence band is dominating. The impurity content in the substrates especially Li is reduced by the high temperature annealing step and drops further close to the detection limit in the films. The low substrate temperatures around 660°C allow for the incorporation of nitrogen on oxygen site as a shallow acceptor. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.