The electrical characteristics of degenerate InP Schottky diodes with an interfacial layer

Abstract

Degenerate Au-n+-type InP Schottky diodes are fabricated using anodic oxidation, etching with aqueous HCl and annealing in a N2 atmosphere. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics are measured and discussed. High barrier heights qφB are obtained even in degenerate samples; for example, qφB =0.76 eV. The observed increase in qφB is caused by an interfacial layer between the metal and semiconductor. It is found that annealing in a N2 atmosphere prior to the evaporation of the Au contact is effective to increase the effective interfacial thickness δ/ε*i, and therefore, qφB. Here δ and ε*i are respectively the thickness and relative dielectric constant of the interfacial layer. The intercept on the voltage axis of the 1/C2 vs V plot is found to be considerably large compared with φB. This is also explained by the effect of the interfacial layer. The interface state density is estimated as 0.2–1×1013 eV−1 cm−2. The volume charge within the interfacial layer is discussed and found to be negative.