Hall measurements on liquid phase epitaxial In1−xGaxAsyP1−ylattice matched to InP have been performed in the temperature range 300≤T(K)≤600 °C. The crystals were grown at 640 °C. Anomalous lowering of the mobility and carrier concentration has been observed at these temperatures for certain alloy compositions. It is believed that clustering due to miscibility gaps existing in these solid compositions is responsible for the observed data. Interpretations of the data based on this assumption have been made.