Thermally stable Pd/Ge ohmic contacts to n-type GaAs

Abstract
The thermally stable Pd/Ge ohmic contacts to n‐type GaAs are obtained by a rapid thermal annealing method. Compared to the conventional AuGe based ohmic metals, the surface morphology is smooth with high uniformity of constituent. A small deterioration from 1.01.0× 10−5 Ω cm2 to 1.2 × 10−5 Ω cm2 is observed at 300 °C for 103 h. The activation energy was 1.9 eV and the lifetime of this contact, defined as the time of 10% deterioration, is expected to be over 109 years at 70 °C. The mechanism of the deterioration for Pd/Ge ohmic contacts is also discussed, utilizing Auger electron spectroscopy and x‐ray photoemission spectroscopy analysis.