# Formation of two-dimensional electron and hole gases at the interface of half-Heusler semiconductors

## TL;DR

This study demonstrates that two-dimensional electron and hole gases can form intrinsically at the interfaces of half-Heusler semiconductors, offering potential for novel electronic devices without chemical doping.

## Contribution

The paper reveals the intrinsic formation of 2DEG and 2DHG at half-Heusler interfaces through electronic structure calculations, expanding understanding of interface properties in these materials.

## Key findings

- 2DEG and 2DHG form without doping at specific interfaces
- Charge densities reach 3x10^14 carriers/cm^2
- Formation depends on band alignment and interface termination

## Abstract

Heuslers are a prominent family of multi-functional materials that includes semiconductors, half metals, topological semimetals, and magnetic superconductors. Owing to their same crystalline structure, yet quite different electronic properties and flexibility in chemical composition, Heusler-based heterostructures can be designed to show intriguing properties at the interface. Using electronic structure calculations, we show that two dimensional electron or hole gases (2DEG or 2DHG) form at the interface of half-Heusler (HH) semiconductors without any chemical doping. We use CoTiSb/NiTiSn as an example, and show that the 2DEG at the TiSb/Ni(001) termination and the 2DHG at the Co/TiSn(001) termination are intrinsic to the interface, and hold rather high charge densities of 3x10^14 carriers/cm^2. These excess charge carriers are tightly bound to the interface plane and are fully accommodated in transition-metal d sub-bands. The formation of 2DEG and 2DHG are not specific to the CoTiSb/NiTiSn system; a list of combinations of HH semiconductors that are predicted to form 2DEG or 2DHG is provided based on band alignment, interface termination, and lattice mismatch.