Comparative study on the formation of Cr and Ti ohmic contacts to (001) β-Ga₂O₃

Journal Article · Wed Feb 18 00:00:00 UTC 2026 · Journal of Vacuum Science and Technology A

DOI: https://doi.org/10.1116/6.0005214 · OSTI ID:3023254

Schettini Mejía, Carlo A.  ^[1]; Kisslinger, Kim T.  ^[2]; Williams, Isabella ^[1]; Chen, Xipin ^[1]; Yang, Judith C.  ^[2]; Porter, Lisa M.  ^[1]

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1. Carnegie Mellon Univ., Pittsburgh, PA (United States)
2. Brookhaven National Laboratory (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)

Here, a comparative study of Cr/Au and Ti/Au ohmic contacts on (001) β-Ga₂O₃ was conducted. The electrical behavior from current-voltage measurements and the interfacial composition and microstructure as determined from high-resolution transmission electron microscopy (TEM) with energy dispersive x-ray analysis were compared for the different contacts at selected points in an annealing series (300–700 °C, 1 min. anneals in N₂). Cr/Au contacts became ohmic at temperatures (300–350 °C) approximately 50–100 °C lower than Ti/Au contacts (400–450 °C). Cr/Au and Ti/Au contacts demonstrated optimal ohmic behavior (lowest resistance) when annealed to 450–500 and 500–600 °C, respectively, with Ti/Au contacts yielding a lower total resistance than Cr/Au. Cross-sectional TEM images of Cr/Au contacts annealed at 450 °C revealed the presence of Au nanoclusters at the Ga₂O₃ interface and CrO_x layers at both the top of the contact and the Ga₂O₃ interface. Whereas TiO_x also formed at the top and bottom interfaces in 450 °C-annealed Ti/Au contacts, the TiO_x surface layer appeared to be variable in thickness and/or discontinuous, unlike the CrO_x surface layer. Au nanoclusters were not detected at the interface in the Ti/Au contacts. The interdiffusion and oxidation observed in both contact metallizations point to the need for diffusion barriers that may allow these contacts to be used in future Ga₂O₃-based devices that operate at elevated temperatures.

• Research Organization: Brookhaven National Laboratory (BNL), Upton, NY (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF)
• Grant/Contract Number: SC0012704
• OSTI ID: 3023254
• Report Number(s): BNL--229539-2026-JAAM
• Journal Information: Journal of Vacuum Science and Technology A, Journal Name: Journal of Vacuum Science and Technology A Journal Issue: 2 Vol. 44; ISSN 0734-2101; ISSN 1520-8559
• Publisher: American Vacuum Society / AIPCopyright Statement
• Country of Publication: United States
• Language: English