As-doped p-type ZnO produced by an evaporation∕sputtering process

Strongly p-type ZnO is produced by the following sequence of steps: (1) evaporation of Zn3As2 on a fused-quartz substrate at 350°C; and (2) sputtering of ZnO with substrate held at 450°C. The electrical characteristics include: resistivity of 0.4Ωcm, a mobility of 4cm2∕Vs, and a hole concentration of about 4×1018cm−3. This resistivity is among the best (lowest) ever reported for p-type ZnO. Secondary-ion mass spectroscopic analysis gives an average As concentration about 5×1019cm−3, and a simple one-band fit of the temperature-dependent mobility curve yields an acceptor concentration of about 9×1019cm−3. This is strong evidence that the p-type dopant involves As, although it is not clear whether the acceptor is simply AsO or the recently suggested AsZn−2VZn.