MODELING OF ELECTROLYTE ELECTROREFLECTANCE OF HEAVILY-DOPED N-TYPE GAAS

The electroreflectance of highly doped semiconductors has been modeled , taking into account both Franz-Keldysh and band-filling (Moss-Burste in) effects. Comparisons are made between theoretical and experimental electrolyte electroreflectance results obtained from an n-type GaAs e lectrode of dopant density approximately 1 X 10(18) cm-3 in a 0.1-M KO H solution. The form of the experimental line shape with applied poten tial is successfully predicted, and details of Fermi-level pinning of both ac and dc potentials are deduced. Band-gap narrowing and the posi tion of the Fermi level are discussed and the relative prominence of t he Franz-Keldysh and Moss-Burstein effects compared, and it is shown t hat the low mass of the majority carriers implies that the observed li ne shape can only be accurately modeled when both effects are consider ed.