Ohmic Contact to Phosphorous-Doped ZnO Using Pt∕Ni∕Au for p-n Homojunction Diode

The electrical properties of single Pt and Pt multilayer contacts on moderately doped were investigated. Although linear current–voltage characteristics were observed for all samples, a sample that was annealed for at a temperature above resulted in an ohmic contact with good characteristics. The best ohmic contact to p-type was obtained using a multilayer contact that was annealed at for under a ambient, showing a specific contact resistance of . The fundamental mechanisms for the lower contact resistivity of contacts are discussed based on glancing-angle -ray diffraction results and Auger depth profile analysis of the multilayer alloying process. Furthermore, we fabricated a p–n homojunction using and as the p-type and n-type ohmic contact metal, respectively. The threshold voltage was determined to be about , comparable to the bandgap energy of .