We present the characteristics of Ti/Pt/Au Schottky contacts on wide bandgap InGaP semiconductors with surface pre-treatment before Schottky contact deposition, and investigate the influence of post heat treatment on Schottky diodes. With the pre-deposition surface etching by dilute HCl, dilute NH4OH, or buffer oxide etchant (BOE), the performance of Schottky diodes compared with samples without surface pre-treatment is improved significantly. Auger electron spectroscopy (AES) analysis of the thermally annealed Schottky diode has been performed to investigate the failure mechanism. No significant change was found for samples annealed up to 450°C. However, a drastic degradation of the barrier height and the ideality factor was observed in samples annealed at 500°C, which may be caused by the interdiffusion and penetration of metals into the semiconductor.
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