Electroreflectance modelling of a low-field dielectric contributions requiring a Boltzmann model of carrier density

Abstract

Electrorefiectance spectroscopy is a useful diagnostic tool for potential and field distribution in semiconductors, and spectra from experiments performed on samples taken from highly doped (neardegenerate) wafers of Ill-V materials have been compared with theory. Satisfactory modelling has been achieved using recent advances in the understanding of the Moss-Burstein (band-filling) effect, and the accurate modelling of bandgap narrowing and other heavy doping prupernes IS a 5 0 uemonstrareo.The Moss-Burstein effect makes its principal contribution to the dielectric function in the low-field region, as does that of excitonic absorption, and both effects are shown to require special computational considerations with respect to the electric field profile. When a Boltzmann carrier concentration (rather than a Schottky depletion) model is used, the calculated result for the Moss-Burstein eI,c:cL rapluly ti;urtve,!jeo LU L I E Ciurreti, ,U~es,,ape.Ute oGIlutmy uep,auu,, model is shown to result in much siower convergence to a signal of much smaller magnitude, and a simple excitonic calculation shows the same tendencies, clearly demonstrating the importance of a correct field profile model,