Tailoring Heterovalent Interface Formation with Light

TL;DR

This paper demonstrates that UV illumination during molecular beam epitaxy can modify heterovalent interfaces, improving bond quality and reducing defects, thereby enhancing the optical properties of semiconductor heterostructures.

Contribution

It introduces a novel method of using UV light during growth to tailor interface chemistry and defect levels in heterovalent semiconductor interfaces.

Findings

UV illumination alters chemical bond composition at the interface.

UV light promotes formation of Ga-Se bonds for passivation.

Illumination reduces defects in ZnSe epilayers.

Abstract

Integrating different semiconductor materials into an epitaxial device structure offers additional degrees of freedom to select for optimal material properties in each layer. However, interface between materials with different valences (i.e. III-V, II-VI and IV semiconductors) can be difficult to form with high quality. Using ZnSe/GaAs as a model system, we explore the use of UV illumination during heterovalent interface growth by molecular beam epitaxy as a way to modify the interface properties. We find that UV illumination alters the mixture of chemical bonds at the interface, permitting the formation of Ga-Se bonds that help to passivate the underlying GaAs layer. Illumination also helps to reduce defects in the ZnSe epilayer. These results suggest that moderate UV illumination during growth may be used as a way to improve the optical properties of both the GaAs and ZnSe layers on either side of the interface.