Use of Ti/W/Cu, Ti/Co/Cu and Ti/Mo/Cu multi-layer metals as Schottky metals for GaAs Schottky diodes

Abstract

New Schottky structures (Ti/W/Cu, Ti/Co/Cu, Ti/Mo/Cu),with copper and refractory diffusion barrier metal, for GaAs Schottky diodes were evaluated. For the widely used Ti/Pt/Au Schottky diode, the thick overcoat gold layer was replaced with copper; Pi layer was replaced with the transition metals such as W, Co and Mo. The choice of the refractory metals was I based on their resistivity and the capability as the anti-diffusion barrier. The multi-layer metals were sputtered on the surface of n-GaAs. The Schottky metals were annealed at 15.0degreesC-300degreesC after deposition. Them ideality. factor and Schottky barrier height are 1.08/0.78eV, 1.07/0.71eV and 1.06/0.76eV for Ti/W/Cu, Ti/Co/Cu and Ti/Mo/Cu. structure respectively after annealing at 150degreesC for 2 minutes. The electrical properties of these contacts are, comparable with the typical Ti/Pt/Au Schottky diode which has an ideality factor close to 1.07. From the XkD results, the Ti/W/Cu and Ti/Mo/Cu Schottky structures are thermally stable after annealing up to 400degreesC for 30 minutes; Ti/Mo/Cu Schottky structure is. thermally stable up to 300degreesC annealing for 30min These results show that the new. Schottky. structure's have excellent electrical characteristics compare to the traditional Ti/Pt/Au structure and can be used as the Schottky metals for GaAs devices.