Local ultra-violet surface photovoltage spectroscopy of single thread dislocations in gallium nitrides by Kelvin probe force microscopy

The local carrier properties, including minority diffusion lengths and surface recombination velocities, were measured at single thread dislocations in GaN film by a combination of surface photovoltage spectroscopy and Kelvin probe force microscopy. The thread dislocations introduced by a nanoindentation were observed as V-pits, where the photovoltage was lower than that on plane surface under ultra-violet illumination. A model is proposed to fit the spatially resolved surface photovoltage spectroscopy curves. Compared with those on plane surface, the hole diffusion length is 90 nm shorter and the surface electron recombination velocity is 1.6 times higher at an individual thread dislocation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4772538]