Effects of bromine-methanol and hydrogen chloride pretreatments on Pt/Al/n-InP diodes

Abstract

This paper reports the passivation effects of bromine-methanol (Br/M) and hydrogen chloride (HCl) treatments on the n-InP surface to form Pt/Al/n-InP diodes. It was found that Br/M and HCl passivated the n-InP surface. The Br/M-dipped and the HCl-dipped Pt/Al/n-InP diodes exhibited a barrier height of 0.83 and 0.86 eV, respectively, and a low reverse leakage current of 7.07 x 10(-7) and 1.10 x 10(-7) A/cm(2) at -3 V, respectively. The secondary ion mass spectroscopy and electron spectroscopy for chemical analysis showed that the Br/M or HCl treatment made formation of bromides and chlorides on the n-InP surface, respectively. They also revealed the existence of Al2O3, which is believed to be formed with the native In2O3 during the Al evaporation. This, which made the diodes be of the metal-insulator-semiconductor structure, in conjunction with the passivation effect of bromides and chlorides, improved the diode characteristics and produced the high barrier heights.