Formation Mechanism of CuPt-Type Sublattice Ordering for III-III-V Type Compound Semiconductors

This paper discusses a possible formation mechanism of CuPt-type sublattice ordering for III-III-V type compound semiconductors by taking Ga0.5In0.5P grown on (001)GaAs as an illustrative example. The proposed mechanism relies on: (1) a particular reconstruction (‘step-terrace reconstruction (STR)’ model) on vicinal (001) surface with a misorientation towards [111]B direction, (2) a large contraction of P-P distances of P-P dimers, (3) both bond-length and bond-energy differences between Ga-P and In-P, (4) a steric effect, i.e, surface-atom position dependent atom-adsorption effect and (5) step-flow growth. These assumptions of the mechanism are examined in the light of available experimental results. Sublattice ordering in III-V-V type compounds is also briefly discussed in connection with that for III-III-V type compounds