Scanning photocurrent microscopy in single nanowire devices

Abstract

Scanning photocurrent microscopy (SPCM) is a powerful technique for investigating local electronic structures and charge transport in semiconductor nanowires. Here we apply this technique to explore colloidal PbSe nanowires and VO 2 nanobeams. Field effect transistors incorporating single colloidal PbSe nanowires were fabricated. A fast, sensitive polarization-dependent photoresponse was observed. SPCM of as-grown PbSe nanowires showed a downward band bending towards the metal electrodes, consistent with their p-type nature. At 54 °C, SPCM of VO 2 nanobeams revealed band bending at the metallic/insulating domain boundaries. At room temperature, we observed photocurrent spots in the middle of the VO 2 nanobeams, indicating local electric fields likely caused by defects.