The electrical conductivity and the Hall effect were investigated in the temperature region from 77 to 1000K on undoped ZnO single crystals grown by vapour phase transport. The growth conditions were systematically altered to get crystals with definite non-stoichiometry. The electrical properties were related to these growth conditions. The analysis of the Hall data yields the phase boundary ZnO/Zn and a formation enthalpy of 1.5eV for the dominant native donor. This donor was suggested to be the oxygen vacancy. The Hall mobility was analysed with regard of new aspects giving a smaller anisotropy than in earlier analyses.

Electrical Properties and Non-Stoichiometry in ZnO Single Crystals. Ziegler, E., Heinrich, A., Oppermann, H., Stöver, G.: Physica Status Solidi A, 1981, 66[2], 635-48