Depletion-Mode Photoconductivity Study of Deep Levels in GaN Nanowires

摘要

The steady-state photoconductivity (PC) response of deep level defects to sub-bandgap illumination was studied in GaN nanowires (NWs) grown by metalorganic chemical vapor deposition. Photoemission from defects residing in the NW surface depletion region alters the depletion width, and the PC response arises mainly from the resulting enhancement of the cross-sectional area of the electrically conductive NW core. The advantages of emphasizing depletion region processes for deep level spectroscopy of NWs are discussed. A simple electrostatic model was adopted to explain the strong relative increase of sub-bandgap PC response with decreasing NW width. NW deep level spectra were similar to those widely reported for planar GaN films, suggesting that the corresponding defects are located throughout the NW volume and are not specific to the surface.