Determination of the piezo-optical properties of semiconductors above the fundamental gap by means of reflectance difference spectroscopy

Reflectance difference spectroscopy (RDS) has been used to determine piezo- optical coefficients of semiconductors above the fundamental gap. The high sensitivity of the RDS technique allows the determination of these coeffici ents with the use of very small uniaxial stresses (<0.05 GPa). By measureme nt of RDS on samples of cubic crystals under uniaxial stress along the [001 ] and [111] crystal directions, the piezo-optical coefficients P-11 - P-12 and P-44, respectively, were determined. Measurements on InP give results i n good agreement with previously reported values obtained by ellipsometry. RDS was used successfully to determine the spectral dependence of P-11 - P- 12 in ZnSe, a II-VI semiconductor too brittle to support the stresses requi red for ellipsometric measurements. RDS is less sensitive than ellipsometry to the presence of surface overlayers. (C) 1999 Optical Society of America [S0740-3232(99)02303-0].