Potential profile and photovoltaic effect in nanoscale lateral pn junction observed by Kelvin probe force microscopy

Nanoscale pn junctions have been investigated by Kelvin probe force microscopy and several particular features were found. Within the depletion region, a localized noise area is observed, induced by temporal fluctuations of dopant states. Electronic potential landscape is significantly affected by dopants with ground-state energies deeper than in bulk. Finally, the effects of light illumination were studied and it was found that the depletion region shifts its position as a function of light intensity. This is ascribed to charge redistribution within the pn junction as a result of photovoltaic effect and due to the impact of deepened-level dopants.