Face-to-face anneal temperature controls lattice parameter in Ta(C,N) virtual substrates for AlGaN power electronics
Abstract
Tantalum carbide (TaC) thin film ''virtual'' substrates are a highly desirable material for Al0.5Ga0.5N vertical power electronics devices due to lattice matching, thermal expansion matching, and metallic conductivity. However, the material has not been demonstrated to support AlxGa1−xN layers of variable composition x, limiting the range of device applications. We present a method to achieve tunable rock salt TaCxN1−x virtual substrates via a face-to-face annealing of TaC thin films in an N2 atmosphere. The results suggest that annealing temperatures below 1600 ∘C promote partial uptake of nitrogen onto carbon and anion vacancy sites to form rock salt Ta(C,N) with intermediate anion compositions. At temperatures ≥ 1600 ∘C, nitrogen primarily occupies the anion sublattice and the crystalline quality and surface morphology simultaneously degrade coincident with the formation of secondary phases. This study demonstrates the growth and processing parameters necessary to make tunable lattice constant virtual substrates for AlxGa1−xN from x = 0.5−1, enabling vertically conducting power electronic devices with reduced defect density at high Al-content.
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BibTeX
@misc{zahn2026facetoface,
title = {{Face-to-face anneal temperature controls lattice parameter in Ta(C,N) virtual substrates for AlGaN power electronics}},
author = {Noah Zahn and Julia L. Martin and Michelle A. Smeaton and Renae Gannon and Henry Garland and M. Brooks Tellekamp},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.24893},
eprint = {2609.24893},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.24893},
}
RIS
TY - UNPB
TI - Face-to-face anneal temperature controls lattice parameter in Ta(C,N) virtual substrates for AlGaN power electronics
AU - Noah Zahn
AU - Julia L. Martin
AU - Michelle A. Smeaton
AU - Renae Gannon
AU - Henry Garland
AU - M. Brooks Tellekamp
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.24893
UR - https://arxiv.org/abs/2609.24893
AB - Tantalum carbide (TaC) thin film ''virtual'' substrates are a highly desirable material for Al_0.5Ga_0.5N vertical power electronics devices due to lattice matching, thermal expansion matching, and metallic conductivity. However, the material has not been demonstrated to support Al_xGa_1−xN layers of variable composition x, limiting the range of device applications. We present a method to achieve tunable rock salt TaC_xN_1−x virtual substrates via a face-to-face annealing of TaC thin films in an N_2 atmosphere. The results suggest that annealing temperatures below 1600 ^∘C promote partial uptake of nitrogen onto carbon and anion vacancy sites to form rock salt Ta(C,N) with intermediate anion compositions. At temperatures ≥ 1600 ^∘C, nitrogen primarily occupies the anion sublattice and the crystalline quality and surface morphology simultaneously degrade coincident with the formation of secondary phases. This study demonstrates the growth and processing parameters necessary to make tunable lattice constant virtual substrates for Al_xGa_1−xN from x = 0.5−1, enabling vertically conducting power electronic devices with reduced defect density at high Al-content.
ER -