Time-Resolved In Situ Spectroscopy During Formation of the GaP/Si(100) Heterointerface.

Though III-V/Si(100) heterointerfaces are essential for future epitaxial high-performance devices, their atomic structure is an open historical question. Benchmarking of transient optical in situ spectroscopy during chemical vapor deposition to chemical analysis by X-ray photoelectron spectroscopy enables us to distinguish between formation of surfaces and of the heterointerface. A terrace-related optical anisotropy signal evolves during pulsed GaP nucleation on single-domain Si(100) surfaces. This dielectric anisotropy agrees well with the one calculated for buried GaP/Si(100) interfaces from differently thick GaP epilayers. X-ray photoelectron spectroscopy reveals a chemically shifted contribution of the P and Si emission lines, which quantitatively corresponds to one monolayer and establishes simultaneously with the nucleation-related optical in situ signal. We attribute that contribution to the existence of Si-P bonds at the buried heterointerface. During further pulsing and annealing in phosphorus ambient, dielectric anisotropies known from atomically well-ordered GaP(100) surfaces superimpose the nucleation-related optical in situ spectra.

Formation of GaP/Si(100) Heterointerfaces in the Presence of Inherent Reactor Residuals.

Adequate silicon preparation is a prerequisite for defect-free III-V growth on Si. We transfer the silicon processing from clean to GaP containing metalorganic vapor phase epitaxy reactors, where we monitor the entire process in situ with reflection anisotropy spectroscopy and analyze the chemical composition of the surface with X-ray photoelectron spectroscopy. Beyond a certain submonolayer threshold value of (Ga,P) residuals found on the Si(100) surface, GaP grows with an inverted majority sublattice. Analogously to III-V growth on two-domain substrates, the coexistence of Si-Ga and Si-P interfacial bonds at terraces of the same type causes antiphase disorder in GaP epilayers.