Annealing-induced interfacial reactions and the effects on the electrical properties of Ga doped ZnO/CuxS contacts to p-GaN

Ga-doped ZnO (GZO) contacts to p-GaN were investigated by using CuxS interlayers under different annealing temperatures. It is shown that the GZO/CuxS contacts annealed at 300 and 400 °C for 3 min in air exhibited non-ohmic characteristics. However, annealing the contacts at 500 and 600 °C in air resulted in linear current-voltage characteristics. The lowest specific contact resistivity of 1.66 × 10−2 Ω cm2 was obtained for the contact annealed at 500 °C. To account for the formation mechanism of the ohmic contact, AES and XPS were used to analyze the interfacial properties of the GZO/CuxS/p-GaN and CuxS/p-GaN interfaces, respectively. The possible reasons were discussed in detail, suggesting that the interfacial reactions and atomic diffusions are thought to be responsible for forming such a low contact resistance.