Atomic scale analysis of the GaP/Si(100) heterointerface byin situreflection anisotropy spectroscopy andab initiodensity functional theory

Abstract

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.

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

“…7 In principle, the inversion of the GaP sublattice could also be explained by Si−P bonds combined with either (i) B-type Si(100), (ii) substitutional P adsorption or (iii) an additional Ga/P interlayer forming one ML below the uppermost Si atoms. However, these processes would then only occur during pulsed nucleation on Si cont and not on Si clean .…”

Dielectric Anisotropy of the GaP/Si(001) Interface from First-Principles Theory

“…Interface RA has been measured in several cases including InP=GaAsð001Þ [16], ZnSe=GaAsð001Þ and SiO 2 =Sið112Þ [17], AlAs=GaAsð001Þ [18], and GaP= Sið001Þ [5,12,13]. There have been few calculations of optical interface anisotropies.…”

“…RA [5,12,13], LEED, XPS, and density functional theory (DFT) calculations [12,14] have shown that GaP grown on Si(001) by MOVPE has a mixed (2 × 2) and cð4 × 2Þ P dimer surface. The dimers are tilted and have a H atom on the down-tilted P atom.…”

Electronic structure of GaP/Si(001) heterojunctions and the role of hydrogen passivation

“…Although it has been experimentally demonstrated that the GaP/Si(001) interface is typically sharp (with a maximum interface region extension over one monolayer), it has been shown that the intermixed or terraced GaP/Si(100) interfaces atomic configurations are thermodynamically more favorable than the atomically abrupt one. Therefore, we performed the same calculations on intermixed (compensated) and terraced interfaces in order to compare the EDOS of the abrupt and hydrogenated structures with those of compensated and terraced interfaces.…”