Atomic composition of WC/ and Zr/O-terminated diamond Schottky interfaces close to ideality

Electrical and nano-structural properties of Zr and WC-based Schottky power diodes are compared and used for investigating oxide-related effects at the diamond/metal interface. Differences in Schottky barrier heights and ideality factors of both structures are shown to be related with the modification of the oxygen-terminated diamond/metal interface configuration. Oxide formation, oxide thickness variations and interfacial oxygen redistribution, associated with thermal treatment are demonstrated. Ideality factors close to ideality (nWC = 1.02 and nZr = 1.16) are obtained after thermal treatment and are shown to be related with the relative oxygen content at the surface (OCRWC = 3.03 and OCRZr = 1.5). Indeed, thermal treatment at higher temperatures is shown to promote an escape of oxygen for the case of the WC diode, while it generates a sharper accumulation of oxygen at the metal/diamond interface for the case of Zr diode. Therefore, the metal-oxygen affinity is shown to be a key parameter to improve diamond-based Schottky diodes.