Photoemission-Based Photovoltage Probe of Semiconductor Surface and Interface Electronic Structure

A saturation surface photovoltage is found to occur during ultraviolet photoemission at low temperatures ($T\sim 20$ K) on a variety of silicon (111) surfaces. Below ∼ 50 K surface recombination becomes ineffective thereby allowing flat-band conditions to be achieved with mild uv irradiation. Temperature-dependent photoemission thereby provides a simple and direct method for determining band bending and barrier heights. Results for different silicon (111) surfaces and preparation conditions are discussed.