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

The electrical characteristics of rhodium-based metal contacts on n-Ga As have been studied by varying the deposition technique, annealing ti me and temperature, and the pretreatment of the substrate. In particul ar, the contact properties of evaporated (by electron beam and resisti ve evaporation) and chemically deposited (electroless plating and elec trodeposition) Rh layers have been investigated. Evaporation under ult ra-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 defe cts is believed to cause the barrier increase.