Fine structure of the alloy-broadened thermal emission spectra from D X centers in GaAlAs

Deep level transient spectroscopy in Si- and Sn-doped GaAlAs reveals a fine structure of the DX center thermal emission spectra under adequate filling pulse and sampling window times. This structure is reproducible in samples with Al mode fractions near 30% but it is not detectable in samples with 85% Al content. All resolved peaks of this fine structure have the same thermal emission energy but quite different capture cross section (σ∞n). This fact indicates that the origin of the fine structure and of the nonexponential behavior of the thermal emission processes is the discrete broadening of σ∞n due to the alloy effect.