Optical characterization of the “E2” deep level in GaN

Abstract
The correspondence between the E2 level (∼Ec −0.55 eV) in n-type GaN undergoing thermoionization and photoionization was established. The optical cross section in the vicinity of the threshold for photoionization of this level was measured by means of capacitance transient spectroscopy. Analysis using the formulation of Chantre yielded the optical activation energy, Eo =0.85 eV, and the Franck–Condon parameter, dFC=0.30 eV at 90 K.