Research Focus

• Understanding how to integrate van der Waals materials like Bi2Se3 with industrially-relevant semiconductor materials like GaAs(001) using molecular beam epitaxy (MBE) for THz applications.
• Determining the chemical composition and bonding type of the Bi2Se3/GaAs(001) interface using density functional theory (DFT) calculations.

Key Advances

• Even with the highly lattice mismatched substrate GaAs(001), we can obtain high-quality, single crystalline, single orientation Bi2Se3 films using a superlattice smoothing layer on the GaAs substrate and in vacuo transfer to prevent interfacial oxidation.
• The Bi2Se3/GaAs interface quality strongly influences the film quality even in van der Waals epitaxy.
• DFT calculation results for the interface chemical composition indicates that the interface is Se-terminated GaAs with a van der Waals gap between the GaAs and Bi2Se3. STEM imaging also supports the conclusion.

Interdisciplinary Research Group (IRG) 2: Hybrid Quantum Materials with Emergent Terahertz Functionalities (HQ-METs)