Molecular beam homoepitaxy of N-polar AlN: enabling role of Al-assisted surface cleaning

Zexuan Zhang; Yusuke Hayashi; Tetsuya Tohei; Akira Sakai; Vladimir Protasenko; Jashan Singhal; Hideto Miyake; Huili Grace Xing; Debdeep Jena; YongJin Cho

arXiv · 2204.08604

Molecular beam homoepitaxy of N-polar AlN: enabling role of Al-assisted surface cleaning

Zexuan Zhang·Yusuke Hayashi·Tetsuya Tohei·Akira Sakai·Vladimir Protasenko·Jashan Singhal·Hideto Miyake·Huili Grace Xing·Debdeep Jena·YongJin Cho

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Abstract

N-polar aluminum nitride (AlN) is an important building block for next-generation high-power RF electronics. We report successful homoepitaxial growth of N-polar AlN by molecular beam epitaxy (MBE) on large-area cost-effective N-polar AlN templates. Direct growth without any in-situ surface cleaning leads to films with inverted Al-polarity. It is found that Al-assisted cleaning before growth enables the epitaxial film to maintain N-polarity. The grown N-polar AlN epilayer with its smooth, pit-free surface duplicates the structural quality of the substrate as evidenced by a clean and smooth growth interface with no noticeable extended defects generation. Near band-edge photoluminescence peaks are observed at room temperature on samples with MBE-grown layers but not on the bare AlN substrates, implying the suppression of non-radiative recombination centers in the epitaxial N-polar AlN. These results are pivotal steps towards future high-power RF electronics and deep ultraviolet photonics based on the N-polar AlN platform.

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Zexuan Zhang, Yusuke Hayashi, Tetsuya Tohei, Akira Sakai, Vladimir Protasenko, Jashan Singhal, Hideto Miyake, Huili Grace Xing, Debdeep Jena, YongJin Cho. 2022-04-19. Molecular beam homoepitaxy of N-polar AlN: enabling role of Al-assisted surface cleaning. https://arxiv.org/abs/2204.08604

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