Manifestation of the equilibrium hole distribution in photoluminescence of n-InN

Photoluminescence (PL) of n-InN grown by molecular beam epitaxy with Hall concentrations from 3.6 to 7.3 x 10(17) cm-3 demonstrates dependences on carrier concentration, temperature, and excitation density which give evidences of a fast energy relaxation rate of photoholes and their equilibrium distribution over localized states. The structure of the PL spectra observed at 4.2 and 77 K in the energy interval from 0.50 to 0.67 eV indicates that a considerable part of holes is trapped by deep and shallow acceptors before the interband recombination with degenerate electrons occurs. At room temperature, the hand-to-hand recombination of free holes and electrons dominates in PL. Experimental results on PL and absorption are described by model calculations under the assumptions of a band gap equal to 0.665-0.670 eV at zero temperature and zero carrier concentration and a non-parabolic conduction band with the effective mass at the Gamma-point equal to 0.07 of the free electron mass.