Ohmic Contact of Ti/Au Metals on n-type ZnO Thin Film

The Ohmic contact of Ti/Au metals on n-type ZnO thin film deposited on c-plane sapphire substrates by pulsed laser deposition was investigated by TLM (transfer length method) patterns. The Ti/Au metal films with thickness of 35 nm and 90 nm were deposited by electron-beam evaporator and thermal evaporator, respectively. By using the photo-lithography method, the TLM patterns with gaps were formed. To improve the electrical properties as well as to decrease an interface states and stress between metal and semiconductor, the post-annelaing process was done in oxygen ambient by rapid thermal annealing system at temperature of for 1 min. In this study, it appeared that the minimum specific contact resistivity shows about in annealed sample, which may be originated from formation of oxygen vacancies of ZnO during an oxidation of Ti metal at the interface of Ohmic contacts.