Growth of Al xGa 1− xP on GaAs substrate by metalorganic vapor phase epitaxy

Abstract

The crystalline perfection of the Al x Ga 1− x P film grown on GaAs substrate by atmospheric pressure metalorganic vapor phase epitaxy has been studied using double-crystal X-ray diffraction and back-scattering spectrometry, and the behavior for the optical phonons of the Al x Ga 1− x P epilayer investigated by the Raman scattering technique. In addition, the reflection spectra in the visible-light spectra region from multilayer structures constructed by Al x Ga 1− x P/GaP pairs have been measured. The measurement of the full-width at half-maximum of the X-ray diffraction peak of the Al x Ga 1− x P epilayer showed that the crystalline perfection of the Al x Ga 1− x P film was improved by growing a GaP buffer layer and using a misoriented GaAs substrate. Corresponding to the temperature range 750–820°C, the higher crystalline perfection was obtained at the lower growth temperature. The value of the minimum yield of back-scattering spectrometry of Al 0.24Ga 0.76P/GaAs (3.4×10 −2) revealed that the epilayer was not perfect and contained both elastic strain and misfit dislocations. A two-mode Raman characteristic of Al 0.21Ga 0.79P/GaAs was clearly seen with two LO modes, AlP-like LO and GaP-like LO located at 460 and 392 cm −1, respectively. For the (Al 0.21Ga 0.79P) 10/(GaP) 10 structure, a reflectivity above 60% was realized.