THE THERMAL-STABILITY OF OHMIC CONTACT TO N-TYPE INGAAS LAYER

Abstract

The thermal stability of ohmic contact to n-type InGaAs layer is investigated. When Ni/Ge/Au is used as the contact metal, the characteristics of the ohmic contact are degraded after thermal treatment. The specific contact resistance of (Ni/Ge/Au)-InGaAs ohmic contact after annealing at 450 degrees C is about 15 times larger than that of as-deposited sample. This is due to the decomposition of InGaAs and the interdiffusion of Ga and Au.-A new phase of Au4In appears after annealing at 300 degrees C. While in the case of Ti/Pt/Au, Au does not penetrate into the InGaAs layer as revealed by secondary ion mass spectroscopy. The specific contact resistance of(Ti/Pt/Au)-InGaAs ohmic contact after annealing at 450 degrees C is eight times larger than that of as-deposited sample. Therefore, the thermal stability of(Ti/Pt/Au)-InGaAs ohmic contact is better than that of(Ni/Ge/Au)-InGaAs ohmic contact.