Band-edge excitons in gallium arsenide on silicon

Study of thermal strain relaxation in GaAs grown on Ge/Si substrates

“…In agreement with literature data [7], we attribute the high energy band to the m j ¼ AE 3 2 and the low energy band to the m j ¼ AE 1 2 exciton recombination, respectively. The relative intensity of the two components is consistent with this attribution: thermal population effects favour the low energy component, which is then the dominant one, despite the lower oscillator strength [7]. The observed red-shift and splitting values are compatible with a residual strain in the GaAs epilayer of 0.18-0.20%.…”

“…Two bands, peaked at 1.502 eV and at 1.486 eV, characterize the spectra. Comparison with literature on the low temperature PL data of GaAs/Si allows us to attribute these two transition to the exciton recombination [7]. Low temperature PL excitation spectra, not reported here, show for the structure at 1.486 eV an excitation band at slight higher energy, thus confirming the attribution of the bands at 1.502 and 1.486 eV to bound exciton transitions.…”

Analysis of strain relaxation by microcracks in epitaxial GaAs grown on Ge∕Si substrates

“…Furthermore, antiphase domains can be effectively eliminated using intentionally misoriented substrates ͑see, e.g., Ref. 11 These results are confirmed by literature calculations of the spatial dependence of the strain in the film plane in a direction perpendicular to a crack. It has been shown that also for Ge/ SiGe/ Si substrates the double-layer step structure characteristic for pure Si is preserved, such that also in this case antiphase domain formation can be prevented.…”

“…2 are shown in the lower panel of Fig. 11 On the contrary, for high energy separations, that is at large distances from the crossing point, thermal population effects favor the low energy component, which becomes the dominant one. Very close to the point of intersection ͑d Ϸ 0͒ the -PL spectrum is characterized by a single structure whose peak energy ͑1.514 eV͒ coincides with that of the donor bound exciton in bulk GaAs.…”

Evidence for large configuration-induced band-gap fluctuations inGaAs1−xNxalloys

“…27 Nevertheless, in GaAs͑001͒ with biaxial tensile strain, the ratio of the oscillator stengths of the lh and hh transitions remains close to the 1 : 3 ratio of the spin multiplicities. 28 It follows that the absorption coefficient of our samples should be modeled with Eq. (2) using two different sets of parameters to independently reproduce the lh and hh transitions.…”