Fermi-edge enhancement in the luminescence of the AlGaN/GaN heterostructure

Abstract

Modualtion-doped Al0.12Ga0.88N/GaN single heterostructures have been investigated by means of photoluminescence (PL) measurements. The radiative recombination of the two-dimensional electron gas (2DEG) with photogenerated holes has been observed at 3.552 eV. The temperature dependence of 2DEG emission shows that the energy separation between the 2DEG and the donor bound exciton emissions ((DX)-X-0) related to GaN increase with increasing temperature. This results from the screening effect of electrons attributed to the bending of the conduction band at the heterointerface. The full width at half maximum of the 2DEG emission becomes broader from 80 K to 180 K because of thermal broadening of the Fermi-edge. This phenomenon provides evidence of Fermi-edge enhancement in the luminescence spectra of the 2DEG subband near the Fermi level.