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

摘要

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 coefficients with the use of very small uniaxial stresses (<0.05 GPa). By measurement 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 in 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 required for ellipsometric measurements. RDS is less sensitive than ellipsometry to the presence of surface overlayers.