Line shape analysis of electron–hole plasma electroluminescence in fully strained SiGe epitaxial layers

The electroluminescence of p-i-n diodes with fully strained Si0.80Ge0.20 /Si(001) is dominated by radiative recombination in an electron–hole plasma. The recombination mechanisms and the band gap renormalization have been studied experimentally and by modeling. In order to minimize the influence of the SiGe/Si interface regions and thus to study the intrinsic behavior of strained SiGe, electroluminescence diodes with thick layers of SiGe in a metastable strain state have been investigated. To explain the electroluminescence spectra, the band filling model for an electron–hole plasma system and different broadening procedures have been investigated. This line shape analysis allowed the determination of the dependence of the renormalized band gap on carrier density and comparison with theoretical predictions was done. The low-energy tails of the electroluminescence spectra correspond to a broadening of the initial electronic states of the recombination process in electron–hole plasma system. The experimental data obtained from the line shape analysis of the electroluminescence spectra are in good agreement with previous results on spectral photocurrent and quantum efficiency measurements. © 2003 American Institute of Physics. @DOI: 10.1063/1.1606513#