Space-charge-limited-current diode model for the rectifying-to-ohmic transition with Au/Al contacts to CdS

The space-charge-limited-current diode model indicates that the rectifying-to-ohmic transition properties of Au/Al contacts to CdS are controlled by a trap at 0.6 eV below the conduction-band edge of the CdS interface with the metal. The trap densities vary between 4 and 10 (1016) cm−3 and the rectification degrades as the band bending asymmetry in the interface decreases from 0.206 to 0.158 eV with the introduction of the Al. The model provides a good fit of both the forward bias current and the nonsaturating reverse bias current characteristics using parameter values that are consistent with those found by other workers using deep-level transient spectroscopy.