Growth of AlxGa1−xP on GaAs substrate by metalorganic vapor phase epitaxy

The crystalline perfection of the AlxGa1−xP 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 AlxGa1−xP epilayer investigated by the Raman scattering technique. In addition, the reflection spectra in the visible-light spectra region from multilayer structures constructed by AlxGa1−xP/GaP pairs have been measured. The measurement of the full-width at half-maximum of the X-ray diffraction peak of the AlxGa1−xP epilayer showed that the crystalline perfection of the AlxGa1−xP 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 Al0.24Ga0.76P/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 Al0.21Ga0.79P/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 (Al0.21Ga0.79P)10/(GaP)10 structure, a reflectivity above 60% was realized.