AuGePt ohmic contact to n-type InP

Abstract

This work studied the AuGe to n-InP/ohmic contact system with the addition of Pt. It studied two contact schemes, i.e., Au/Ge/Pt/n-InP and Au/Pt/Au/Ge/n-InP. The specific contact resistances, the thermal stability, as well as the microstructure of the system, were systematically studied with the aid of scanning electron microscopy, Auger electron spectroscopy, Rutherford backscattering analysis, and x-ray diffraction. The processing condition to achieve the optimum contact resistance was also sought and it was found that a specific contact resistance of 2.15x10(-6) Ohm cm(2) could be obtained if the Au/Ge/Pt/n-InP contact system was rapid thermal annealed at 550 degrees C for 30 s. The system was also found to be able to achieve low specific contact resistances for a wide range of anneal temperature from 400 to 550 degrees C. It was found that the Pt existence in-between AuGe and InP improved the surface morphology, the contact interface uniformity, and the thermal stability. The system could withstand a thermal aging at 400 degrees C for 80 h with only a minimal increase on the specific contact resistance. (C) 1996 American Institute of Physics.