ATOMIC ORDERING AND ITS INFLUENCE ON THE OPTICAL AND ELECTRICAL PROPERTIES OF INGAP GROWN BY MOVPE

摘要

The anisotropy of the electrical and optical properties of ordered In_xGa_(1-x)P epitaxial layers prepared by low-pressure metalorganic vapor-phase epitaxy at a reactor pressure of 20 or 50 mbar was studied. Resistivity measurements using a four-point probe method showed that samples with a low misfit (0 up to -1.5 x 10~(-3)) were electrically uniform. For samples with higher misfit, the anisotropy in the resistivity increased markedly to a maximum of 460. Disordered samples prepared at a growth temperature outside of the "ordering" interval were found to be electrically uniform with respect to lattice mismatch. The band-gap energy reduction caused by the ordering effect closely follows the theoretical prediction of Wei and Zunger. As follows from our results, the band-gap energy of tensile strained (x < 0.485) and ordered In_xGa_(1-x)P conforms to the theoretical predictions made for a degree of order η lower than 0.2.