Excellent rectifying characteristics in Au/n-CdTe diodes upon exposure to rf nitrogen plasma

Nitrogen plasma exposure (NPE) effects on indium doped bulk n-CdTe are repo rted here. Excellent rectifying characteristics of Au/n-CdTe Schottky diode s, with an increase in the barrier height, and large reverse breakdown volt ages are observed after the plasma exposure. Surface damage is found to be absent in the plasma exposed samples. The breakdown mechanism of the heavil y doped Schottky diodes is found to shift from the Zener to avalanche after the nitrogen plasma exposure, pointing to a change in the doping close to the surface which was also verified by C-V measurements. The thermal stabil ity of the plasma exposure process is seen up to a temperature of 350 degre es C, thereby enabling the high temperature processing of the samples for d evice fabrication. The characteristics of the NPE diodes are stable over a year implying excellent diode quality. A plausible model based on Fermi lev el pinning by acceptor-like states created by plasma exposure is proposed t o explain the observations.