SURFACE EFFECTS ON CURRENT MECHANISMS IN 6H-SIC N(+)PP(+) STRUCTURES PASSIVATED WITH A DEPOSITED OXIDE

Bipolar n(+)pp(+) diodes fabricated by nitrogen implantation and passi vated with a deposited oxide have been characterized. Current-voltage measurements in a large temperature range have been analyzed. We also used the optical beam induced current method to represent the depleted zone at the surface around a reverse-biased device. We show that phen omena as the diameter-dependent current for low reverse and forward bi ases, the specific value for the energy activation of current under lo w bias equal to 0.65 eV, the reverse current-voltage characteristics e volution with time, or the anomalous spread of the depleted layer arou nd a reverse-biased diode can be correlated with the presence of the d eposited oxide as a passivation layer. A study of the current-time cha racteristic, obtained for a set reverse bias, is used to prove the pre sence of charges in the oxide and interface states responsible for an eventual inversion channel along the mesa. (C) 1998 American Institute of Physics.