Correlation of InGaP(001) surface structure during growth and bulk ordering

CuPtB-type ordering of InGaP grown lattice matched to GaAs was investigated by in situ reflectance anisotropy spectroscopy and reflection high-energy electron diffraction. The experiments have been performed during InGaP grow th bath via metal-organic vapor phase epitaxy and chemical beam epitaxy. Ad ditionally, total energy;calculations (TE) have been performed for differen tly ordered InGaP slabs. From both experiment and TE calculations we conclu de that bulk ordering only occurs when InGaP growth is performed under phos phorus-rich (2 X 1)-like surface conditions. Bulk ordering completely disap pears under growth conditions which cause a less-phosphorus-rich (2 X 4)-li ke surface dimer configuration. P dimers in the (2 X 1) symmetry at the gro wth surface trigger the bulk ordering driven by an energy gain of 0.26 eV p er surface atom according to our TE calculations.