(NH4)(2)S-x-treated InP(100) surfaces studied by soft x-ray photoelectron spectroscopy

The sulfur chemical bonding state on (NH4)(2)S-x-treated InP(100) surfaces has been studied by S Is core-level photoelectron measurements using synchrotron radiation soft x-rays. The change in the sulfur chemical bonding states caused by rinsing with water and annealing in vacuum after the (NH4)(2)S-x-treatment was observed clearly in the S 1s spectra. Four kinds of sulfur bonding states were resolved in the S Is spectrum of the as-treated surface. Only one sulfur bonding state was detected on the surfaces with and without the water rinse after annealing, indicating that the InP surfaces were terminated by the S-In bond. The effect of rinsing the (NH4)(2)S-x-treated InP surface is discussed by comparison with the (NH4)(2)S-x-treated GaAs surface.