Effect of cryogenic temperature deposition on Au contacts to bulk, single-crystal n-type ZnO

Au contacts were deposited on bulk, n-type single-crystal ZnO at either 77 Kor 300 K.The room temperature deposition produced contacts with ohmic characteristics. By sharp contrast, the cryogenic deposition produced rectifying characteristics with barrier heights around 0.4 eV. The differences in contact behavior were stable to anneal temperatures of 300 8C. There were no differences in near-surface stoichiometry for the different deposition temperatures, while the low temperature contacts showed a more uniform appearance. With further optimization of the predeposition cleaning process, this may be a useful method for engineering barrier heights on ZnO.