PIEZOOPTICAL RESPONSE OF SEMICONDUCTORS

The effects of uniaxial stress on the optical properties of Si, Ge, Ga As, InP and GaP have been investigated using rotating analyser ellipso metry. Under the presence of an external stress described by the secon d-rank tensor X(ij), changes in the dielectric tensor epsilon(ij)(omeg a) are linked to X(ij) by the fourth-rank symmetric tensor (piezo-opti cal tensor) P(ijkl)(omega) such that DELTAepsilon(ij)(omega) = P(ijkl) (omega)X(ij). For diamond and zinc blende types of semiconductors thre e independent functions P11(omega), P12(omega) and P44(omega) are requ ired to characterize this tensor fully. Measurements of these function s were performed at room temperature, with the optical path kept in ai r, in the visible range (homegaBAR almost-equal-to 1. 5 - 5.4 eV) and the values compared with extensive existing information (polarized ref lectivity and piezoreflectance) as well as calculations with the empir ical pseudopotential method. We review the piezoellipsometry technique and present some new results.