Abstract:
Based on the analysis of low-temperature stimulated emission spectra, conclusions are drawn about the band gap narrowing effect ($\Delta E_{\mathrm{BGN}}$) in degenerate, $n\sim$10$^{19}$ cm$^{-3}$, epitaxial InGaN films with an indium content of 60% under intense photoexcitation. A red shift of the generation line is demonstrated due to the large $\Delta E_{\mathrm{BGN}}$ exceeding 2 meV/10$^{17}$ cm$^{-3}$, apparently provided by the Coulomb interaction of degenerate (equilibrium) electrons and nonequilibrium holes localized in the local extrema of the fluctuating band potential, with limited contribution from exchange (Hartree–Fock) interaction. This behavior directly determines the features of the competition between modal gain and losses in bulk In(Ga)N films. The obtained results can also be projected onto promising low-dimensional structures for red-range quantum wells emitters with based on “intermediate composition” InGaN.
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