April 7 - 11, 2025
Seattle, Washington
Symposium Supporters
2025 MRS Spring Meeting & Exhibit
EL11.01.03

Atomic and Electronic Structures of Rocksalt-Wurtzite Interfaces with Ultra-Wide Bandgap Nitrides

When and Where

Apr 7, 2025
2:15pm - 2:30pm
Summit, Level 4, Room 435

Presenter(s)

Co-Author(s)

Sharad Mahatara1,Stephan Lany1

National Renewable Energy Laboratoty1

Abstract

Sharad Mahatara1,Stephan Lany1

National Renewable Energy Laboratoty1
Power electronics are crucial for a sustainable energy future, especially in integrating renewable energy sources and electrification. Advances in ultra-wide bandgap materials like high Al-content AlxGa1-xN are essential for efficient power handling but need suitable substrates for lattice matching. Metallic TaC has been proposed as a virtual substrate for AlxGa1-xN heteroepitaxy, as (0001) AlxGa1-xN in the wurtzite structure matches the (111) rocksalt (rs) TaC lattice at x ≈ 0.5. Here, we use first principles DFT to predict the formation of heterostructural rs-wz interfaces between TaC and AlN (GaN) films, using an algorithm to systematically enumerate possible stacking sequences within a few atomic layers near the interface. We determine the lowest energy structure for each combination of substrate termination (Ta or C), film nucleation (Al/Ga or N), and wz polarity (Al/Ga- or N-polar). We further express the total film sheet energy as a function of elemental chemical potentials and construct a "phase diagram" for the most likely structures to form under varying growth conditions. Electronic structure calculations for the most favorable structures predict band alignment, Schottky barrier heights, and interface density of states. Our results provide guidance for synthesis control of substrate-film bonding, film polarity, and resulting electronic properties for ultra-widegap AlxGa1xN alloys on TaC substrates.

Keywords

nitride

Symposium Organizers

Robert Kaplar, Sandia National Laboratories
Filip Tuomisto, University of Helsinki
Motoaki Iwaya, Meijo University
Sriram Krishnamoorthy, University of California, Santa Barbara

Symposium Support

Silver
Taiyo Nippon Sanso

Session Chairs

Robert Kaplar
Georges Pavlidis

In this Session