First-Principles Assessment of ZnTe and CdSe as Prospective Tunnel Barriers at the InAs/Al Interface

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Computing

Background:

• Majorana zero modes are crucial for fault-tolerant topological qubits.
• Semiconductor/superconductor interfaces like InAs/Al are promising for Majorana realization.
• Strong coupling and metal-induced gap states (MIGS) hinder Majorana emergence.

Purpose of the Study:

• To investigate ZnTe and CdSe as tunnel barriers for the InAs/Al interface.
• To mitigate strong coupling and MIGS for improved Majorana device fabrication.
• To determine the optimal barrier material and thickness for InAs-based Majorana devices.

Main Methods:

• Density Functional Theory (DFT) with machine-learned Hubbard U corrections (Bayesian Optimization).
• Validation of DFT+U(BO) results using Angle Resolved Photoemission Spectroscopy (ARPES).
• Simulation of bilayer and trilayer semiconductor/superconductor interfaces.

Main Results:

• 16 atomic layers of ZnTe or CdSe effectively insulate InAs from MIGS.
• ZnTe exhibits an electron-blocking band alignment, while CdSe blocks holes.
• ZnTe is identified as the preferred barrier material due to relevant electron transport for InAs devices.

Conclusions:

• ZnTe is a promising tunnel barrier material for InAs/Al interfaces in Majorana devices.
• A ZnTe barrier thickness of 6-18 atomic layers is recommended for experimental investigation.
• Optimized tunnel barriers are essential for advancing topological quantum computing.