hotoreflectance (PR) and optical absorption (OA) have been used to study the energy-gap dependence on temperature in In1-xGaxAs thin layers, metalorganic vapor-phase epitaxy grown on InP substrates under nearly lattice-matched conditions (‖Δa/a0‖≤10-3). Both PR and OA spectra show a split structure in the band-gap energy region. Moreover, the energy-gap values at all temperatures, obtained by Franz-Keldysh-oscillations analysis of PR line shapes, are blueshifted with respect to the values of the perfectly lattice-matched alloy (x=0.472). The results are related to the valence-band splitting at k=0 generated by the biaxial strain in In1-xGaxAs, due to the small lattice mismatch. We calculated the splitting and shift values using the orbital-strain Hamiltonian and accounting for compositional effects. The values are in agreement with the experimental results giving optical evidence of coherent growth of the alloy film.
Optical study of the strain effect in pseudomorphic In1-xGaxAs-InP heterostructures
GEDDO, MARIO;BELLANI, VITTORIO;GUIZZETTI, GIORGIO
1994-01-01
Abstract
hotoreflectance (PR) and optical absorption (OA) have been used to study the energy-gap dependence on temperature in In1-xGaxAs thin layers, metalorganic vapor-phase epitaxy grown on InP substrates under nearly lattice-matched conditions (‖Δa/a0‖≤10-3). Both PR and OA spectra show a split structure in the band-gap energy region. Moreover, the energy-gap values at all temperatures, obtained by Franz-Keldysh-oscillations analysis of PR line shapes, are blueshifted with respect to the values of the perfectly lattice-matched alloy (x=0.472). The results are related to the valence-band splitting at k=0 generated by the biaxial strain in In1-xGaxAs, due to the small lattice mismatch. We calculated the splitting and shift values using the orbital-strain Hamiltonian and accounting for compositional effects. The values are in agreement with the experimental results giving optical evidence of coherent growth of the alloy film.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
