Complex Airy analysis of photoreflectance spectra for bulk In_xGa_1-xAs on InP and In_xGa_1-xAsHEMTs

摘要

The authors present a detailed, first-principle analysis ofphotoreflectance (PR) spectra using complex Airy functions and theirderivatives. With the use of the complex Airy functions, PR spectradirectly yield band-gap energies (light and heavy hole). The proposedmodel considers three distinct but superimposed features in the PRspectra of InGaAs which represent the light and heavy hole bands and anexciton feature below the band-gap energy. The band-gap features aremodeled using complex Airy functions and their derivatives and thedielectric function of the material. The complex Airy lineshapes areevaluated numerically and fit to the PR spectra using a sequentialsimplex procedure on a personal computer. The complex Airy lineshapesare applied to both intermediate electric field (Franz-Keldyshoscillations) and low field PR spectra, illustrating that complex Airyfunctional analysis represents a generalized treatment. The authorscorrelate energy from the PR spectral fits to those determined fromphotoluminescence measurements