Interfacial reactions of Ni-In and Ni/In/Ni ohmic contacts to n-GaAs

The metallurgical characteristics of codeposited Ni-In and sequentially deposited Ni/In/Ni ohmic contacts to n-GaAs with a total Ni:In atomic ratio of about 1 were investigated in this study. After annealing below 400 °C, only NiIn phase was detected and no interfacial reaction was observed in Ni-In contact, whereas NixGaAs phase was formed at the interface in Ni/In/Ni contact. An extensive interfacial reaction occurred and some epitaxial phases were formed after annealing at 400 °C and above. NiGa and InxGa1−xAs were the final main phases in both the contacts. Furthermore, both the contacts became ohmic after annealing at 400 °C and the above temperatures. The appearance of ohmic behavior was correlated with the formation of interfacial InxGa1−xAs.