LPE Growth and Surface Morphology of In_xGa_1-xAs_yP_1-y (y≤0.01) on (100) GaAs

The effects of the growth conditions (growth time, growth temperature and melt concentration) on the surface morphology of an LPE layer of In_xGa_1-xAs_yP_1-y(y≤0.01) on a (100)GaAs substrate are studied. The change in morphology originates from the relation between the growth temperature (T_g) and the equilibrium saturation temperature (T_s) of the source melt, which is in equilibrium with the quaternary solid but is not in equilibrium with the GaAs substrate. The equilibrium temperature was determined from growth layer thickness data, as well as by analysing the phase diagram. It was found that partial growth of the quaternary layer can take place on GaAs even at T_g>T_s, and this is supported by partial melt-back of the substrate. A mirror-like smooth surface was obtained even if the supersaturation ΔT was as low as 1°C.