BEHAVIOR OF AU-INP SCHOTTKY DIODES UNDER HEAT-TREATMENT

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 In 2O3 in the Au film and Au and O diffusion through the Au/InP interface at 340 °C.