Effects of the Surface on CuPt Ordering During OMVPE Growth

Abstract

Ordered structures are formed in semiconductor alloys spontaneously during growth. This paper describes the surface-related driving force for CuPt ordering and the processes occurring at the surface during growth. The effects of several growth parameters on the surface structure and the ordering process are described. The effects of ordering on the optical and electrical properties of these alloys are also described along with a brief discussion of how this phenomenon might be useful in device structures. The bulk of the paper relates to the newly-discovered use of surfactants for control of ordering during the organometallic vapor phase epitaxial growth of GaInP. Several donor and acceptor dopants are known to produce disorder. The mechanisms for the donors Te and Si and the acceptor Zn are discussed. Perhaps the most exciting development in this area is the use of isoelectronic group V elements, for example Sb, to control the surface structure and, hence, the degree of order and bandgap energy of GaInP. At an estimated Sb concentration in the solid of 10-4, the order is eliminated. Surface photo absorption data indicate that the effect is due to a change in the surface reconstruction. Modulation of the TESb flow rate during the growth cycle has been used to produce a heterostructure with a 135 meV bandgap difference between two layers having the same solid composition.