Optical and transport properties of InSb thin films grown on GaAs by metalorganic chemical vapor deposition

摘要

Optical and transport properties of InSb thin films grown on GaAs by metalorganic chemical vapor deposition (MOCVD) have been investigated by far-infrared (FIR) reflectance spectroscopy. The lattice vibration behaviors of a series of MOCVD InSb/GaAs(100) materials grown under different growth conditions were studied. Effects of Ⅲ-Ⅴ source ratios on the films crystalline quality were examined. Two additional weak modes in the wavenumber regions of 210-240 cm~(-1) were observed and they appeared more prominent at low temperatures. Interference fringe effects modify the FIR reflectance band of the GaAs substrate, which are related to the uniformity of film thickness and crystalline perfection. The dielectric constant, phonon modes and other optical parameters, as well as transport properties including carrier concentration, mobility, effective mass were calculated theoretically and compared with experimental results. The obtained distribution values of the InSb LO phonon mode frequency, line width, relative integrated intensity ratio between the forbidden and defect-related TO phonon and the allowed LO mode are adopted as figures of merit for the quality of the InSb films. The electrical transport properties of carrier concentration, mobility, and effective mass as well as the dielectric constant of these films have been determined by optical method non-destructively.