The Study on the Optical Properties of InAs by Raman Spectroscopy

In this thesis, we use Raman spectroscopy to investigate the lattice vibrational modes of InAs grown by molecular beam epitaxy (MBE). The Raman spectra of InAs epilayers for various carrier concentrations shows that the carriers strongly interact with the LO mode for n-type semiconductors, which results in coupled plasmon modes (L_) and the unscreened LO phonon mode within the accumulation layer on the surface. With the variety of laser power excitation, we observe the undoped InAs sample strongly dependent on the incident power. The LO-plasmon couple mode (L_) reduces the surface field due to the photo-generated carriers. The thickness of the accumulation layer therefore become thinner. Compared to the undoped sample, the heavily doping InAs has little effect on the incident power and the thickness nearly remains constant because the amount of the photo-generated carriers is nearly equal to the doping concentration. .