Surface photovoltage measurements in liquids

We present a simple, compact, and robust arrangement for surface photovolta ge measurements of free semiconductor surfaces immersed in liquids. It is b ased on the classical Kelvin probe arrangement, where the semiconductor sam ple is put in a liquid-containing, electrically insulating vessel, with an optically transparent window, situated between the sample and the Kelvin pr obe. At the price of permitting relative, rather than absolute, contact pot ential difference values, this modification enables easy, routine surface p hotovoltage measurements of semiconductors in any kind of liquid ambient. T he validity and efficiency of this approach are demonstrated by surface pho tovoltage spectra obtained from the p-InP(100) surface in various liquid et chants. (C) 1999 American Institute of Physics. [S0034- 6748(99)03910-6].