Time‐resolved photoluminescence characterization of 2 eV band in AlN

Abstract

We report time‐resolved and temperature‐dependent photoluminescence investigations of 2 eV photoluminescence band in AlN with below bandgap excitation. Series of the samples grown by molecular beam epitaxy on sapphire substrates with varying growth conditions have been studied. Intensity of the 2 eV photoluminescence band has been found to increase with increasing III/V flux ratio. The 2 eV photoluminescence band has been described in one‐dimensional configuration coordinate model. A possible origin of this orange emission has been discussed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Slow decay of a defect‐related emission band at 2.05 eV in AlN: Signatures of oxygen‐related DX states

“…With the longer laser pulses used for excitation in our experiments, we finally expect more of such center states to be filled as compared to experiments using short laser pulses (1 ns pulse width) as those performed by Aleksandrov et al. , that is, this long tail observed by us necessarily escapes observation in their experiments. For the state, the wave function for this second bound electron is expected to be much more localized than for the shallow state, resulting in longer time constants for the DAP recombination — as observed here.…”

“…186 meV in Ref. ) to a transition of the electron from the bound state to a CB free electron state. For the latter states, the wave function overlap with strongly localized deep acceptor states should increase, and thus the lifetime compared to DX‐acceptor transitions should shorten significantly, as the prefactor in the fit to the temperature‐dependent lifetimes (Fig.…”

“…The splitting into two bands was ascribed to different small lattice relaxation states of the complex . Another group attributed the transition at 2.0 eV to a DAP transition with as acceptor .…”

Recombination processes in structures with GaN/ALN quantum dots

“…8 shows the dependence of the probability of electrontunneling (w e ) from a QD to the defect on the electron energy in the QD, which is set by the QD size. The tunneling probability was calculated for two luminescent AlN centers well studied in [26,27]. These centers are related to point defects and described by the following parameters: S¼8.1, 84 meV ω = , E def ¼2.1 eV and S¼20, 60 meV ω = , E def ¼ 2.6 eV.…”

“…The matrix element was assumed to be independent of the defect parameters. The defect parameters are (1) E def ¼ 2.6 eV[27], and (3) S 20, 60 meV ω = = , E def ¼3.5 eV (best agreement inFig. 6).…”