PTGE OHMIC CONTACT TO N-TYPE INP

Abstract

A new ohmic contact system, Ge/Pt/Ge/Pt/n-InP, was studied systematically by measuring its specific contact resistance and by using Auger electron spectroscopy, x-ray-diffraction analysis, Rutherford backscattering spectroscopy, and scanning electron microscopy. It was found that the system has a wide temperature range for annealing, i.e., 450-550 degrees C, to achieve the specific contact resistance of the order of 1.0x10(-5) Omega cm(2). It can achieve a low specific contact resistance of 7.71x10(-6) Omega cm(2) when it is subjected to rapid thermal annealing at 500 degrees C for 30 s. The whole process is a solid phase reaction so that a smooth surface morphology is obtained. The ohmicity is due to the heavy doping of Ge in the regrown InP film. The contact system exhibits good thermal stability, being able to maintain a low specific contact resistance of 9.15X10(-6) Omega cm(2) for 20 h, 400 degrees C aging, and 2.77x10(-5) Omega cm(2) for 80 h aging. (C) 1995 American Institute of Physics.