Low temperature cathodoluminecence and electron beam induced current studies of single GaN nanowires

Single crystalline GaN nanowires, with 100 nm typical diameters, were grown by chemical vapor deposition method, using Pt catalyst, and characterized by cathodoluminescence and electron beam induced current (EBIC) measurements at 5 K. The near band edge emission was found to be asymmetric and broad, with full width half maximum of around 150 meV, peaking at 3.55 eV, well above the GaN bulk band gap. This blueshift was ascribed to band filling effect resulting from unintentional n-type doping in the range 1019–1020 cm−3. Despite of this heavy doping, EBIC experiments showed that minority carriers can diffuse over 0.2 μm.