Lu Yang, Ziqian Sheng, Siliang Kuang, Wenjing Xu, Yaxin He, Xu Zhang, Xiangyu Xu, Kelvin H. L. Zhang
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引用次数: 0
Abstract
GaN-based ultraviolet light emitting diodes (UV LEDs) have attracted considerable attention in recent years and are required in various applications such as healthcare, light illumination, and optical communication. However, the limited UV transparency of the electrodes like indium-doped tin oxide has hindered the external quantum efficiency of current UV LEDs. In this work, we present the growth of UV-transparent Ta-doped SnO2 (TTO) thin films on GaN as a promising UV-transparent electrode for LEDs. TTO thin films with a thickness of 200 nm exhibit optical transmission exceeding 80% at the wavelength of 300 nm, with a low resistivity of 2.5 × 10−4 Ω·cm and a low contact resistance of 1.7 × 10−2 Ω cm2 to n-type GaN. High-resolution x-ray photoemission spectra were employed to reveal insight into the electronic structure of TTO and the interfacial band alignment of TTO/GaN heterojunction. The wide optical bandgap (∼4.6 eV) and high UV transparency of TTO films stem from a significant Burstein–Moss shift due to degenerate doping, giving rise to metal-like characteristics and a small barrier height at the interface of TTO/GaN. These findings imply the origin of low contact resistivity of TTO to n-type GaN and may be applicable to the development of UV-transparent electrodes of optoelectronic devices.
期刊介绍:
Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology.
In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics.
APL Perspectives are forward-looking invited letters which highlight recent developments or discoveries. Emphasis is placed on very recent developments, potentially disruptive technologies, open questions and possible solutions. They also include a mini-roadmap detailing where the community should direct efforts in order for the phenomena to be viable for application and the challenges associated with meeting that performance threshold. Perspectives are characterized by personal viewpoints and opinions of recognized experts in the field.
Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.