Surface strain contributions to the lineshapes of reflectance difference spectra for one-electron and discrete-exciton transitions Conference Paper uri icon

abstract

  • Reflectance difference spectroscopy (RDS/RAS) constitutes a very sensitive tool for the study of the optical properties of semiconductors. RDS spectra comprise several components of different physical origins. One of these components is the strain induced by the surface. In the present work, we report RD spectra measured on GaAs at room temperature at around E1 and the E1%2bΔ 1 transitions. Two cases were studied, the surface strains induced by the c(4x4) reconstruction and by the vacancies generated by the annealing of semi insulating GaAs crystal. Fits to the line shape of the c(4x4) reconstructed and annealed spectra were performed by using a surface strain component for one-electron and discrete-exciton lineshapes respectively. The character of the fits were interpreted by estimating the piezoelectric field induced by surface strain. For the c(4x4) surface the strength of the field partially quenches the exciton while for the annealing surface this field is fifty times lower, and an excitonic lineshape is expected. We also inferred that the RD spectra include a component related to surface roughness. © 2008 Wiley-VCH Verlag GmbH %26amp; Co. KGaA.

publication date

  • 2008-01-01