Passivation mechanism analysis of sulfur-passivated InGaP surfaces using x-ray photoelectron spectroscopy

We present the passivation mechanism and the chemistry of an (NH4)(2)S-x tr eated (100) InGaP surface using x-ray photoelectron spectroscopy. The nativ e oxide on the as-etched InGaP surface could be further removed by a suitab le (NH4)(2)S-x-treatment process. The measured x-ray photoelectron spectra revealed that the S atoms, in addition to bonding to the elemental sulfur, also bonded with the In and Ga atoms on the (NH4)(2)S-x-treated InGaP surfa ce. However, the S atoms occupied the phosphorous-related vacancies instead of bonding with the P atoms. A proposed structural model of a sulfur-passi vated surface is then presented. (C) 2000 American Institute of Physics. [S 0021-8979(00)02209-X].