Correlation of resistance and interfacial reaction of contacts to n-type InP

Metal contact of compound semiconductors has been extensively studied using various characterization tools. However, there was little work of scanning transmission electron microscopy (STEM) done previously for the study of the InP contact systems. Using STEM and Auger electron spectroscopy analyses, we correlated the resistance with interfacial reactions in the AuGe/Ni/Au/Cr/Au contacts to n-InP. Detailed nanoscale structural and chemical information was uniquely revealed by the STEM compared to other techniques. For the high-resistance samples, little interfacial reaction between n-InP and Au occurred. For the low-resistance samples, significant out-diffusion of P in the Au and Ni layers occurred, forming Au–P and Ni–P metallic compounds. Accumulation of Ge in the Ni layer was also detected. We suggest that Ni–P may be very critical in obtaining low contact resistance for n-InP.