Ordered structure inGa0.7In0.3P alloy

Abstract

To explore the generation mechanism of spontaneously ordered structure, a ${\mathrm{Ga}}_{0.7}$ ${\mathrm{In}}_{0.3}$P alloy grown on a ${\mathrm{GaAs}}_{0.6}$ ${\mathrm{P}}_{0.4}$ substrate is examined by transmission electron diffraction. Contrary to the thermodynamic prediction using first-principles theory, in which luzonite-type and/or famatinite-type ${\mathrm{Ga}}_3$ ${\mathrm{In}}_1$ ${\mathrm{P}}_4$ structures are expected, a CuPt-type ordered structure is found. The probable atomic arrangement is a (${\mathrm{Ga}}_{0.7\mathrm{-}\mathrm{\eta }}$ ${\mathrm{In}}_{0.3+\mathrm{\eta }}$P)(${\mathrm{Ga}}_{0.7+\mathrm{\eta }}$ ${\mathrm{In}}_{0.3\mathrm{-}\mathrm{\eta }}$P${)}_1$ ordered structure. A spontaneously generated CuPt-type ordered structure in the GaInP system is not a consequence of thermodynamic stability.