Effects of Thickness on Dislocations in GaP on Si Grown by Metalorganic Chemical Vapor Deposition

GaP grown on Si under high V/III ratio by means of metalorganic chemical vapor deposition has been characterized by using conventional and high-resolution transmission electron microscopy. GaP has been grown on Si two-dimensionally from the beginning of the growth under high V/III ratio. Dislocations are not observed when the GaP layer-thickness is less than 90 nm. On the other hand, dislocations are observed at the interface when the GaP layer is thicker than 90 nm. The dislocation density at the interface increases and the GaP/Si interface becomes wavy with increasing thickness. The origins of these dislocations are the thermal stress and the lattice mismatch.