Tailoring Heterovalent Interface Formation with Light

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, interfaces 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 ultraviolet (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.

Defects in Cd3As2 epilayers via molecular beam epitaxy and strategies for reducing them

“…Given the previous success broadband illumination of the growth surface has had on improving the optical properties of II-VI semiconductors grown at low temperature [18], we explore it as a tool for further improving epitaxial Cd3As2. All epilayers discussed up to this point were grown under broadband illumination with 100 W power.…”

Magnetic Interactions and Band Gaps of the (CrO2)2/(MgH2) n Superlattices

“…[31] Additionally, controlling the interface compositions of superlattices is already a mature technology according to the previous experiments. [32][33][34][35] Given that MgH2 has a compatible crystal structure with CrO2, with lattice mismatch of 2% along 𝑎-direction (3.5% along 𝑐-direction), we expect that they could be fabricated to form superlattices. In view of the aforementioned situation, we construct superlattices of CrO2 and MgH2 along the [001] direction to create new ferromagnetic semiconductors.…”

“…Since the band gap is so small compared with the width of the band of ∼2 eV, the double exchange would survive through the situation just like the Peierls insulator state in K2Cr8O16. [26] Table 2 Inspection of the band structure around the Fermi level shows that four bands are (band 35,36,37,38) to be isolated from others. The partial charge density [Figs.…”

“…Given the epitaxial growth of isostructural compounds like VO2/TiO2 (001) [52] and the mature technology of controlling interface compositions of superlattices, [32][33][34][35] we believe that the stable (CrO2)2/(MgH2)𝑛 superlattice is realizable in experiments.…”