Publications Details

Study of CuPt-type ordering and dopant effect of In{sub 0.5}Ga{sub 0.5}P/GaAs using spectroscopic ellipsometry

Lee, H.; Klein, M.V.; Olson, J.M.; Hsieh, K.C.

The CuPt-type ordering and dopant effects of In{sub 0.5}Ga{sub 0.5}P/GaAs epitaxial layers have been studied using spectroscopic ellipsometry and transmission electron microscopy. The degree of ordering was estimated by both transmission electron diffraction and direct band edge, E{sub 0}. Conventional lineshape fitting of E{sub 1}, E{sub 1}+{Delta}{sub 1}, and E{sub 2} gaps using the second derivative of pseudo dielectric functions shows that the peak position and oscillator strength of the E{sub 1} gap are basically a function of CuPt-type ordering whereas their broadening and phase depend mainly on carrier concentration. The decrease of E{sub 1} gap is explained in terms of CuPt-type ordering. In contrast to the E{sub 1} gap, all the lineshape parameters of the E{sub 2} gap depend mainly on CuPt-type ordering. This difference is discussed in terms of apparent {open_quotes}CuAu-type ordering{close_quotes} or Y2 structure which was observed by transmission electron diffraction.