Preparation of RhO2 thin films by reactive sputtering and their characterizations

Thin films of RhO2, which belongs to the family of conducting platinum group metal oxides, were prepared by reactive sputtering. Influences of sputtering parameters, such as rf power and substrate temperature, and postdeposition annealing on crystallinity, chemical bonding state and resistivity of the deposited films were studied, in order to obtain low-resistivity RhO2 thin films. The resistivity of the deposited films decreased with decreasing rf power. Plasma emission measurement suggested that oxidation of Rh proceeded under the low rf power condition. Poorly- crystallized conducting RhO2 thin films with resistivity of 300-500 mu Omega cm were prepared at substrate temperatures below 150 degreesC; the resistivity of the films increased with increasing substrate temperature above 150 degreesC due to the formation of semiconducting Rh2O3. After postdeposition annealing in oxygen atmosphere at up to 700 degreesC, well-crystallized RhO2 films were formed, and the minimum resistivity of 80 mu Omega cm was obtained.