Ohmic contacts to n-GaN using PtIn2

A new metallization scheme has been developed to form Ohmic contacts to n-GaN. Contacts were fabricated by sputtering the intermetallic compound, PtIn2 on metal-organic vapor phase epitaxy grown n-GaN (n similar to 5 X 10(17) cm(-3)) with some of the contacts subjected to rapid thermal annealing. Contacts in the as-deposited state exhibited nearly Ohmic behavior with a specific contact resistance of 1.2 X 10(-2) Ohm cm(2). Contacts subjected to rapid thermal annealing at 800 degrees C for 1 min exhibited linear current-voltage characteristics and had specific contact resistances less than 1 X 10(-3) Ohm cm(2). Auger depth profiling and glancing angle x-ray diffraction were used to examine the interfacial reactions of the PtIn2/n-GaN contacts. Consistent with estimated phase diagram information, the results from Auger depth profiling and glancing angle x-ray diffraction indicated the formation of (InxGa1-x)N at the contact interface, which could be responsible for the Ohmic behavior of PtIn2 contacts. (C) 1997 American Institute of Physics.