Mechanism of twin-reduced III-V epitaxy on As-modified vicinal Si(111)

Abstract

Rotational twins are fundamental defects in III-V epitaxy, in particular for the growth on nonpolar (111) surfaces. Based on density functional theory (DFT) calculations, we develop a general model for III-V nucleation on vicinal non-polar (111)-oriented substrates and focus on the important differences in the atomic step configuration of different miscut directions. We verify this model by a relevant materials system when growing GaP epilayers on As-terminated Si(111): Scanning tunneling microscopy measurements reveal the formation of straight double bilayer steps after Aspassivation of the Si(111) surface, which persist after III-V growth, as we display when measuring the buried heterointerface with cross-sectional high-resolution transmission electron microscopy. A twin amount in the GaP epilayers is observed in dependence on the misorientation and our nucleation model explains the underlying mechanisms: The number of back-bonds at the step edges determines the nucleation site. Accordingly, the substrate misorientation towards [112] yields twin-suppression, which is in full agreement with experiment. Finally, we use DFT input for Kinetic Monte Carlo calculations to explain the formation of GaP rotational twins on Si(111):As in order to explain their volume fraction observed by high resolution X-ray diffraction measurements. We thus derive a complete picture of the formation and suppression of rotational twins relevant for low-defect III-V-on-Si integration.

High-Temperature Nucleation of GaP on V-Grooved Si

“…This can be explained by the presence of an As 0 peak in Figure , suggesting the presence of excess As on the surface past the first monolayer. Scanning tunneling microscopy studies in ref showed a relatively high density of adatoms under certain As annealing conditions for (111) Si surfaces, which supports this explanation. The fit suggests that there is a fourth intermediate oxidation state of As present, as well.…”

Structure of Strained Low‐Dimensional Sb by In Situ Surface X‐Ray Diffraction

“…The twin structures are summarized in Figure 1. Following convention for RTD formation on (111) surfaces, [38,39] the twinned and untwinned domains are referred to as α-Sb(111) and β-Sb(111), respectively. The registry between α-Sb(111) and the InAs substrate was Sb atoms on face-centred cubic (FCC)-like adsorption sites and β-Sb(111) on hexagonal close-packed (HCP)-like sites.…”