Spectroscopy of the electron states in self-organized GaN/AlN quantum dots

We present detailed analysis of inter- and intraband transitions in GaN/AlN self-organized quantum dots grown on sapphire, silicon (111) and 6H-SiC substrates. Samples containing quantum dots of different size were characterized by means of transmission electron microscopy, photoluminescence and photo-induced absorption spectroscopy. Interlevel transitions in the conduction band were identified in the 0.52-0.98 eV range covering the telecommunication wavelength band. The s-pz transition ranges from 0.52 eV to 0.8 eV for dots with height of 6 down to 1.5 nm, respectively. Experimental results are compared with theoretical calculations showing that in larger dots the transition energy is governed by the value of the internal field.