Low-vacuum metalorganic vapor phase epitaxy of InGaP and its immiscible growth

InP and InGaP crystal growth on GaAs(100) was carried out by low-vacuum (0.03 Torr) MOVPE. Single crystals of InGaP were obtained on GaAs when the substrate temperature was 670°C. In this low-vacuum MOVPE growth of InGaP, as in conventional MOVPE, the growth rate is limited by the supply of group-III metalorganics, and Ga-element is taken into the grown layer more effectively than In-element. In some cases, immiscible InGaP growth was observed as a compositional separation in the grown layers when the substrate temperature was below 620°C. A model for the crystal growth in low-vacuum MOVPE, which can explain the occurence of the immiscibility, is proposed.