NANOSCALE PHOTOVOLTAIC IMAGING USING THE SCANNING TUNNELING MICROSCOPE

Optical interactions in scanning tunneling microscopy (STM) have been considered. It is shown that when STM is used as a proximal probe of photovoltages it is possible to obtain local information about the physical properties of the subsurface semiconducting material. We find that photovoltaic STM measurements allow us to detect relative changes in bulk properties such as band gap and doping density, on a nanometer scale. These results show that the combination of STM and surface photovoltage are capable of providing not only valuable information about the surface of a material, but also about its bulk properties.