Stability of monodomain III-V crystals and antiphase boundaries over a Si monoatomic step

TL;DR

This study uses density functional theory to compare the stability of different III-V crystal configurations on stepped silicon substrates, revealing that charge compensation at the interface enhances stability over antiphase boundary formation.

Contribution

It demonstrates that charge compensation at hetero-interfaces is more stable than antiphase boundary formation, clarifying the origin of antiphase boundaries in III-V/Si heterostructures.

Findings

Charge compensation configuration is more stable than antiphase boundaries.

Antiphase boundaries originate from coalescence of III-V islands, not Si monoatomic steps.

Stable heterostructures depend on atomic-scale charge distribution and strain analysis.

Abstract

Here, we compare the stabilities of different III-V crystals configurations on stepped Si substrates, with or without anti-phase boundaries, for abrupt and compensated interfaces, using density functional theory. Thermodynamic stability of the different heterostructures is analyzed with an atomic scale description of charge densities distribution and mechani-cal strain. We show that the configuration where a III-V crystal adapts to a Si monoatomic step through change of charge compensation at the hetero-interface is much more stable than the configuration in which an antiphase boundary is formed. This study thus demonstrates that antiphase boundaries commonly observed in III-V/Si samples are not origi-nating from Si monoatomic step edges but from inevitable kinetically driven coalescence of monophase 3D III-V islands.