ELECTRICAL-PROPERTIES OF RH/N-GAAS CONTACTS - A COMPARISON OF DIFFERENT PREPARATION METHODS

The electrical characteristics of rhodium-based metal contacts on n-GaAs have been studied by varying the deposition technique, annealing time and temperature, and the pretreatment of the substrate. In particular, the contact properties of evaporated (by electron beam and resistive evaporation) and chemically deposited (electroless plating and electrodeposition) Rh layers have been investigated. Evaporation under ultra-high vacuum (UHV) conditions and electrodeposition of Rh result in a Schottky barrier height (SBH) of 0.85 eV with ideality values close to unity. Larger barrier values were observed by electroless plating. A further increase up to 1.02 eV was found when the substrate was heat treated prior to deposition. A reduced amount of process-related defects is believed to cause the barrier increase.