Stimulated two-quantum photon–phonon transitions in indirect-gap semiconductors

Abstract

Molecular beam epitaxy of InAs on micro-and nano-scale patterned GaAs(001) substrates was studied. An InAs epilayer grown on the micro-scale patterned substrate exhibits islands with {1 1 3}-type facets, and is similar to that grown on the flat (unpatterned) substrate. In contrast, the preferred growth of InAs on the nano-scale patterned substrate is in the 001 direction and exhibits islands with {1 1 0}-type facets. The thickness of the dense dislocation networks at the interface due to strain relaxation is reduced by the micro-scale pattern in comparison with the flat substrate, while for growth on the nano-scale patterned substrate, the strain relaxes via the formation of stacking faults more than dislocations. X-ray diffraction reveals that the strains in the 300 nm InAs epilayers are nearly fully relaxed, and the patterns tend to decrease the lattice constants of the epilayer, implying mass transport of Ga atoms into the epilayer from the GaAs substrates.

Two-quantum photon-phonon laser

“…In this section we consider the emission rates of photons and phonons via the two-quantum photonphonon transitions in which either the optical or the acoustic components, or both may be stimulated. We follow our article [25], where such transitions have been first examined.…”

“…To a good degree of approximation R t can be regarded as a constant in the vicinity of the band extrema. Taking into account that the transverse acoustic modes are degenerate and using the curves [26] for the optical absorption coefficient versus photon energy in Si and Ge at temperature T=4.2 K , we obtain [25] R t = 410 -31 eV cm 6 c -1 for Si and R t = 510 -30 eV cm 6 c -1 for Ge.…”