Schottky Barrier Parameters and Interfacial Reactions of Rapidly Annealed Au/Cu Bilayer Metal Scheme on N-type InP

Abstract

The influence of rapid thermal annealing effect on the electrical and structural properties of Au/Cu Schottky contacts on n-InP has been investigated by the current-voltage (I-V), capacitance-voltage (C-V), auger electron spectroscopy (AES) and the X-ray diffraction (XRD) techniques. As-deposited sample has a barrier height of 0.64 eV (I- V), 0.76 eV (C-V) which increases to 0.82 eV (I-V), 1.04 eV (C-V) after annealing at 400°C for 1min in nitrogen ambient. However, the barrier height decreases to 0.75 eV (I-V), 0.88 eV (C-V) after annealing at 600°C for 1min. Norde method is also employed to calculate the barrier heights of Au/Cu Schottky rectifiers and the values are 0.66 eV for as-deposited, 0.83 eV for 400°C and 0.76 eV for 600°C annealed contacts. These values are in good agreement with the values obtained from I-V method. From the above observations, it is clear that the Schottky barrier height increases with annealing temperatures up to 400°C. Thus, the optimum annealing temperature for the Au/Cu Schottky contact is 400 o C. Based on the AES and XRD results, the formation of indium phases at the Au/Cu/n-InP interface may be responsible for the increase in the barrier height for the contact annealed at 400°C and a corresponding decrease in leakage current. The decrease in the barrier height after annealing at 500 o C may be due to the formation of Cu-P and Au-P interfacial compounds at the interface. The AFM results showed that the surface morphology of Au/Cu Schottky contact is fairly smooth even after annealing at 500°C.