Secondary emission due to recombination of excitons near indirect band bottom. II. Experimental and theoretical analysis in BiI₃

Abstract

For pt.I see ibid., vol.16, p.4719 (1983). Experimental and theoretical studies are presented on the secondary emission (SE) due to recombination of excitons near the indirect band bottom in BiI3. The authors have made systematic measurements to observe the excitation energy, temperature and sample dependences of SE spectra, and obtain a consistent interpretation on these experimental results applying the theory developed in preceding work. The observed SE spectra consist of the Raman scattering (RS) lines, involving resonant higher-order Raman processes, and the hot luminescence (HL) bands in the scheme. Under the excitation near the indirect absorption edge, the spectral structure of SE reflects the relaxation processes of excitons which are governed by the intraband scattering by acoustic phonons and a non-radiative decay due to crystal imperfections. It is shown that the two parameters characterising these two processes are uniquely determined by fitting the calculated intensities of RS lines to the observed ones, and the computed spectral lineshape of HL using these parameter values reproduces experimental results satisfactorily. The relationship between RS and HL intensities is also discussed by comparing the observed and calculated intensity ratios.