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 0.4 Ω cm, a mobility of 4 cm2∕V s, and a hole concentration of about 4×1018 cm−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 5×1019 cm−3, and a simple one-band fit of the temperature-dependent mobility curve yields an acceptor concentration of about 9×1019 cm−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.
Look, D. C.,
Renlund, G. M.,
Burgener, R. H.,
& Sizelove, J. R.
(2004). As-Doped p-Type ZnO Produced by an Evaporation/Sputtering Process. Applied Physics Letters, 85 (22), 5269-5271.