High-Temperature Hydrogen Sensors Based on Gallium Oxide Heterojunction Diodes
Abstract
Long-term, high temperature operation of Ga2O3 devices is a crucial hurdle that must be overcome before widespread adoption of the technology can be achieved, but is largely absent from the overall body of work. Demonstrations up to this point show devices are either limited by material or dopant instability that leads to performance degradation with time. Herein, Ga2O3-based hydrogen sensors employing Pt Schottky and Cr2O3/Ga2O3 p-n diodes (Mg- and N-doped) were fabricated and evaluated for long-term stability at 600C for 800-1,800 hours, with cyclic exposure to N2 and low-concentration H2 (500-1,500 ppm). Transient current density (measured at -0.1 V) and periodic J-V characterization were used to track performance. Despite gradual declines in sensor signal and sensitivity, devices distinguished hydrogen concentrations throughout weeks of operation. Degradation was architecture-dependent: Cr2O3:Mg degraded gradually, consistent with known Mg migration; the Pt Schottky diode showed dramatic changes after 1,000 hours; and Cr2O3:N showed the lowest but most stable performance before failing at 800 hours. Thermionic emission and Lambert W-based modeling confirmed hydrogen exposure reduces interfacial barrier height via a proton-induced dipole mechanism common to both diode types. TEM of aged Pt Schottky diodes revealed Pt grain growth and microvoid formation as key degradation mechanisms. TOF-SIMS confirmed nitrogen dopants remain confined to the Cr2O3:N layer, supporting N-doping as a stable, lower-performance alternative to Mg-doping
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BibTeX
@misc{callahan2026hightemperature,
title = {{High-Temperature Hydrogen Sensors Based on Gallium Oxide Heterojunction Diodes}},
author = {William A. Callahan and Kingsley Egbo and Anna Sacchi and Michelle Smeaton and Michael Walker and Anna Staerz and Ryan O'Hayre and Andriy Zakutayev},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.15881},
eprint = {2609.15881},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.15881},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - High-Temperature Hydrogen Sensors Based on Gallium Oxide Heterojunction Diodes
AU - William A. Callahan
AU - Kingsley Egbo
AU - Anna Sacchi
AU - Michelle Smeaton
AU - Michael Walker
AU - Anna Staerz
AU - Ryan O'Hayre
AU - Andriy Zakutayev
PY - 2026
DA - 2026/09/14
PB - arXiv
DO - 10.48550/arxiv.2609.15881
UR - https://arxiv.org/abs/2609.15881
AB - Long-term, high temperature operation of Ga2O3 devices is a crucial hurdle that must be overcome before widespread adoption of the technology can be achieved, but is largely absent from the overall body of work. Demonstrations up to this point show devices are either limited by material or dopant instability that leads to performance degradation with time. Herein, Ga2O3-based hydrogen sensors employing Pt Schottky and Cr2O3/Ga2O3 p-n diodes (Mg- and N-doped) were fabricated and evaluated for long-term stability at 600C for 800-1,800 hours, with cyclic exposure to N2 and low-concentration H2 (500-1,500 ppm). Transient current density (measured at -0.1 V) and periodic J-V characterization were used to track performance. Despite gradual declines in sensor signal and sensitivity, devices distinguished hydrogen concentrations throughout weeks of operation. Degradation was architecture-dependent: Cr2O3:Mg degraded gradually, consistent with known Mg migration; the Pt Schottky diode showed dramatic changes after 1,000 hours; and Cr2O3:N showed the lowest but most stable performance before failing at 800 hours. Thermionic emission and Lambert W-based modeling confirmed hydrogen exposure reduces interfacial barrier height via a proton-induced dipole mechanism common to both diode types. TEM of aged Pt Schottky diodes revealed Pt grain growth and microvoid formation as key degradation mechanisms. TOF-SIMS confirmed nitrogen dopants remain confined to the Cr2O3:N layer, supporting N-doping as a stable, lower-performance alternative to Mg-doping
ER -