Photo-assisted field emission and electro-reflectance modulation investigations of GaN nanorod arrays

GaN cathodes with nanometer-scale diameters were produced by plasma and photoelectrochemical etching of the structure formed on the n+-GaN substrate with n+-GaN top active layer. The values of band gap energy for GaN nanorods were determined by electro-reflectance modulation spectroscopy and are 3.374 eV, 3.424 eV, and 3.509 eV for the light and heavy holes, respectively. The energy separation between main (Г) and satellite (Х) valleys was estimated using the field and photo-assisted field emission data and is equal to ∆EГ − X = 1.258 eV.