Non-planar crystal growth of Ga 0.5In 0.5P by metalorganic chemical vapour deposition

Abstract

Layers of Ga 0.5In 0.5P have been grown by low pressure metalorganic vapour phase epitaxy on (100) substrates, which where patterned with normal-mesa and re-entrant grooves. The experiments show fast growth at the groove's side walls at temperatures of 680°C and below, whereas all other facets and all layers grown on planar substrates show but moderate growth rates. The large growth rates are attributed to the small preference for the incorporation of Ga over In at (111)A-like surfaces, which is enhanced in growth on non-planar substrates. The non-stoichiometric incorporation of Ga and In causes the development of strain and subsequently a growth mode transition from two to three-dimensional growth. The resulting rough surface of the side wall facets enables fast growth, whereby the interaction with slower growing facets through the gas phase in the non-planar epitaxy enables the supply of the necessary amount of growth species. At the higher temperatures the preference for incorporation of Ga at the side wall surfaces disappears, and the growth rates and compositions of the side wall facets becomes roughly equal to the growth rates and compositions of the non-planar (100) surfaces and the planar (111)A substrates.