| 摘要 |
PURPOSE:To measure the state of the interface between a compound semiconductor and the insulating film and the state of a surface depletion layer in the semiconductor by irradiating the surface of the semiconductor by laser beams transmitting the insulating film and measuring light Raman-scattered. CONSTITUTION:When laser beams 11 transmit the insulating film 1 and reach up to some thickness in the semiconductor 2, only Raman scattered light generated by the mutual action of a Lo phonon (a longitudinal-wave phonon) 18 of a semiconductor crystal and laser beams 11 is detected by a photomultiplier tube 15 because there are hardly free carriers in the depletion layer 7 of the surface of the semiconductor 2 in the interface if the depletion layer 7 has thickness larger than said one. When the thickness of the surface depletion layer 7 is shallower than the reaching depth of laser beams 11, on the contrary, light Raman-scattered by not only the Lo phonon 18 but also a Lo phonon combining with a plasmon 19 is measured because laser beams 11 transmit the surface depletion layer 7 and reach up to the inside of the semiconductor 2 in which there are free electrons. Accordingly, the two Raman scattered light is counted by a photon counter 16, and both memorized into a comparison circuit 17 are compared, thus comparing and evaluating the states of the interfaces in case of a thick depletion layer and a thin one. |
