Photoreflectance method and apparatus utilizing acousto-optic modulation.

摘要

In an apparatus for determining characteristics of materials by photoreflectance the sample (62) is irradiated by light from a monochromatic light source (50, 51) and a pump beam source (63). The reflected ligth is analyzed by a detector (56), a lock-in amplifier (55), a A/D converter (66) and a computer (70). The d.c. signal of the detector (56) is kept constant for a certain measurement by means of a variable neutral density filter (58) in the monochromatic light beam. By varying the pump beam wavelength and its modulation frequency by the use of an acousto-optical modulator the component layers, their quality and the properties of the various interfaces in the sample (62) are determined.