Low resistivity of Si-doped n -type Al0.68Ga0.32N on sapphire by two-step growth for high power electronics

Chatterjee, Abhishek, Pehlivan, Zeki S., Frentrup, Martin, Dar, Sidra A., Kusch, Gunnar, Kappers, Menno J., Wallis, David J. ORCID: https://orcid.org/0000-0002-0475-7583 and Oliver, Rachel A. 2026. Low resistivity of Si-doped n -type Al0.68Ga0.32N on sapphire by two-step growth for high power electronics. APL Electronic Devices 2 (2) , 026111. 10.1063/5.0324707

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Abstract

Al-rich AlGaN is a promising material for deep-ultraviolet (UV) optoelectronics and high-power electronics, but achieving efficient n-type conductivity on cost-effective sapphire substrates remains a key challenge due to high dislocation densities, defect-assisted compensation, and limited dopant activation. In this work, we investigate Si doping in Al0.68Ga0.32N grown by metal–organic vapor-phase epitaxy and elucidate the compensation mechanisms that constrain conductivity. Cathodoluminescence analysis reveals the appearance of a ∼2.6 eV emission band linked to cation–vacancy complexes involving Si (VIII–n·SiIII), which coincides with a sharp reduction in carrier concentration when the Si-doped AlGaN layer is grown at a moderately high temperature. To mitigate these limitations, we develop a two-step growth approach: a high-temperature non-intentionally doped AlGaN layer that reduces structural defects and improves surface morphology, followed by a low-temperature Si-doped AlGaN layer that suppresses compensation from VIII–n·SiIII complexes. This strategy yields a record-low resistivity of 1.09 × 10−2 Ω cm in Al0.68Ga0.32N on sapphire. These results demonstrate a practical pathway for overcoming doping limits in high-Al-content AlGaN using sapphire, enabling scalable high-performance UV optoelectronic and electronic devices.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Engineering
Additional Information:	License information from Publisher: LICENSE 1: URL: https://creativecommons.org/licenses/by/4.0/, Start Date: 2026-04-16
Publisher:	AIP Publishing
Date of First Compliant Deposit:	27 April 2026
Date of Acceptance:	26 March 2026
Last Modified:	27 Apr 2026 09:30
URI:	https://orca.cardiff.ac.uk/id/eprint/186641

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