Behavior of Au/InP Schottky diodes under heat treatment

Abstract

Variations of barrier heights with heat treatment are observed on Au/(n‐type) InP Schottky diodes. The n‐type InP wafers used are vapor epitaxially grown ({100} face oriented) and have carrier concentrations in the range 4×10¹⁵ to 2×10¹⁶ cm⁻³. Before the deposition of the metal, the surfaces are chemically etched in a bromine‐methanol mixture. Electrical characteristics are reported as a function of isochronous heating cycles from 120 to 340 °C, using conventional Schottky barrier I‐V and C‐V analysis. The barrier heights are in the range 0.42–0.49 eV. Degradation characteristics and decreased barrier heights are observed after a 340 °C heat treatment in N₂ with a residual O₂ atmosphere. Distribution profiles of elemental species obtained by Auger electron spectroscopy associated with an Ar⁺‐ion‐beam sputtering show the interdiffusion between the metal and InP as a function of the heat treatment: out‐diffusion of In and O as a solid solution of In₂O₃ in the Au film and Au and O diffusion through the Au/InP interface at 340 °C.