SEMICONDUCTOR CHARACTERIZATION BY A NEW CONTACTLESS ELECTROREFLECTANCE TECHNIQUE EMPLOYING SURFACE ACOUSTIC-WAVES

The interaction between an amplitude modulated surface acoustic wave o n a piezoelectric substrate and the surface band bending and charge tr apping at an adjacent semiconductor surface is employed to produce a m odulated d.c. electric field in the near-surface region of the semicon ductor. This field perturbs the optical reflectivity of the semiconduc tor, allowing derivative reflectance spectra to be obtained in a manne r analogous to the familiar technique of photomodulated reflectance. T his new contactless electroreflectance technique has been demonstrated by obtaining spectra, including structure above the bandgap, of (ln)G aAs/AlGaAs multiple quantum well structures grown by molecular beam ep itaxy.