REVERSE IV AND C-V CHARACTERISTICS OF SCHOTTKY-BARRIER TYPE DIODES ON ZN DOPED INP EPILAYERS GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

Mesa etched, Au/p-InP Schottky diodes with a thin interface layer [metal-thin interface layer-semiconductor (MIS) diodes] were fabricated by evaporation of Au onto a Zn doped epitaxial layer of InP grown by low pressure metalorganic vapor phase epitaxy, on a highly doped InP substrate. The reverse current-voltage (I(r)-V(r)) and 1 MHz capacitance-voltage (C-V) characteristics of the Au/p-InP MIS diodes were measured in the temperature range 220-393 K. The reverse current in the MIS diodes did not saturate but increased with the increase in the reverse bias voltage. The soft I(r)-V(r) characteristics of the epitaxial Au/p-InP MIS diodes were very well described by the interface layer thermionic emission theory of Wu [J. Appl. Phys. 51, 3786 (1980)] for reverse bias voltages in the range 0-5 V and over the temperature range 300-393 K. In this temperature range, the values of the zero bias barrier height (phi(b0)) obtained from the analysis of the I(r)-V(r)/T characteristic using the self-consistent iterative least square fitting method of Tseng and Wu [J. Appl. Phys. 61, 299 (1987)] agreed very well with those obtained from the C-V/T data. The analysis of the I(r)-V(r)/T data provided the values of (7.5+/-1.7) x 10(-3) and (45+/-22) angstrom for the transmission coefficient and the thickness of the interface layer, respectively. The capacitance-frequency (C-f) data for frequencies in the range 1 kHz up to 1 MHz and for bias voltages between -0.2 and 4.0 V, justify the assumption of voltage independence of the charge trapped in the states localized at the interface layer, made in the analysis of both the I(r)-V(r)/T and C-V/T data.