Characterization of ZnO and Zn_0.95Co_0.05O prepared by sol-gel method using PAC spectroscopy

Abstract

The measurement of the electric field gradient (efg) with PAC spectroscopy was used to follow the heat treatment during the preparation of ZnO samples using sol-gel method. In particular, the investigation was carried out on samples of intrinsically n-type II–VI wurtzite semiconductor ZnO and Co-doped Zn_0.95Co_0.05O samples prepared by sol-gel methodology from pure metallic Zn(99.9999%). Carrier-free ¹¹¹In nuclei were introduced in the samples by thermal diffusion. ¹¹¹In solution was added to the precursor sol-gel solution prior to the formation of gel material. PAC measurements were carried out to follow the formation of the ZnO. Two undoped ZnO samples, which were heated in air and argon atmosphere, show different results. PAC measurements were also used to follow the ¹¹¹In diffusion in a commercially purchased ZnO (99.99%) sample as well as to compare the results with the measurements taken with sol-gel prepared samples. The results show that samples prepared by sol-gel process followed by heating in argon produce better quality ZnO samples. The results also show that the Co atoms in Zn_0.95Co_0.05O are in substitutional sites.