Effects of surfactants N and Br on ordering in GaInP

Formation of the CuPt ordered structure during the organometallic vapor phase epitaxial (OMVPE) growth of GaInP has significant effects on the electrical and optical properties, necessitating control of ordering. Formation of the CuPt structure is thermodynamically driven by the surface structure during growth. This has led to the study of the use of surfactants as a way of controlling ordering. To date, these studies have centered on the group V elements isoelectronic with P. Sb and Bi are both larger than P. This leads to less ordering, N, on the other hand, is smaller than P, which makes it potentially interesting. The other disordering mechanism, observed for Te as a surfactant in GaInP, is kinetic. Rapid step propagation leads to a reduction in ordering. This suggests another potentially interesting class of surfactants, the group VII elements, such as Br, that have been reported to increase the step velocity during OMVPE growth, This paper describes the results of the addition of the surfactants N and Br during the OMVPE growth of GaInP. Addition of N (DMHy) results in a clear reduction in order parameter, due to thermodynamic effects. The addition of Br (CBr4) is also observed to systematically decrease the amount of CuPt ordering and is found to correspond to a significant roughening of the surface, which is postulated to be the origin of the reduction in order parameter.