Surface properties of semiconductors from post-illumination photovoltage\n transient

Free surfaces of semiconductors respond to light by varying their surface\nvoltage (surface band bending). This surface photovoltage may be easily\ndetected using a Kelvin probe. Modeling the transient temporal behavior of the\nsurface photovoltage after the light is turned off may serve as a means to\ncharacterize several key electronic properties of the semiconductor, which are\nof fundamental importance in numerous electronic device applications, such as\ntransistors and solar cells. In this paper, we develop a model for this\ntemporal behavior and use it to characterize layers and nanowires of several\nsemiconductors. Our results suggest that what has previously been considered to\nbe a logarithmic decay is only approximately so. Due to the known limited\nfrequency bandwidth of the Kelvin probe method, most previous\nKelvin-probe-based methods have been limited to slow responding semiconductors.\nThe model we propose extends this range of applicability.\n