Atomic scale analysis of the GaP/Si(100) heterointerface by in situ reflection anisotropy spectroscopy and ab initio density functional theory

A microscopic understanding of the formation of polar-on-nonpolar interfaces is a prerequisite for welldefined heteroepitaxial preparation of III-V compounds on (100) silicon for next-generation high-performance devices. Energetically and kinetically driven Si(100) step formations result in majority domains of monohydrideterminated Si dimers oriented either parallel or perpendicular to the step edges. Here, the intentional variation of the Si(100) surface reconstruction controls the sublattice orientation of the heteroepitaxial GaP film, as observed by in situ reflection anisotropy spectroscopy (RAS) in chemical vapor ambient and confirmed by benchmarking to surface science analytics in ultrahigh vacuum. Ab initio density functional calculations of both abrupt and compensated interfaces are carried out. For P-rich chemical potentials at abrupt interfaces, Si-P bonds are energetically favored over Si-Ga bonds, in agreement with in situ RAS experiments. The energetically most favorable interface is compensated with an intermixed interfacial layer. In situ RAS reveals that the GaP sublattice orientation depends on the P chemical potential during nucleation, which agrees with a kinetically limited formation of abrupt interfaces.