Analysis of interface states of n-InP MIS structures based on bias dependence of capacitance and photoluminescence intensity

Bias dependence of the integrated room temperature photoluminescence (PL) intensity and capacitance measurements, are used to study the interface properties of metal–insulator–semiconductor (MIS) structures realized on indium phosphide (InP). Boron nitride (BN) insulating films have been grown by a radio-frequency (RF) plasma enhanced chemical vapor deposition (PECVD) technique. The capacitance–voltage (C–Vg) measurements are performed in the dark and under illumination. The Termanʹs method was first used to analyze the interface sates distribution. The results proved to be non-reliable. Indeed low (≤5×1011 cm−2 eV−1) and even negative values were obtained particularly from the dark capacitance data. The interface states density is also determined from PL intensity variations versus applied voltage. The obtained distributions of interface states are U shaped with a minimum, nearly 1012 cm−2 eV−1, located around 0.4 eV below the conduction band minimum. This technique, which is frequency independent and less sensitive to the leakage currents in the insulator, leads to more reliable results.