Here, we proposed a novel Al0.9Ga0.1N-delta-GaN QW by inserting an ultra-thin delta-GaN layer into a conventional Al0.9Ga0.1N QW active region. The physics from such QW design was investigated by 6-band k·p model and the structure was experimentally demonstrated by Plasma-assisted Molecular Beam Epitaxy (PAMBE). The calculated results show that the insertion of delta-GaN layer could successfully address the band mixing issue and QCSE, leading to a significant improvement in spontaneous emission rate as compared to that of Al0.55Ga0.45N QW at 260 nm. The 5-period Al0.9Ga0.1N-delta-GaN QW with 3-nm AlN barrier was grown on AlN/sapphire substrate by MBE with ~2-monolayer delta-GaN layer, which was evidenced by the cross-sectional transmission electron microscope. The two-photon photoluminescence spectrum presented a single peak emission centered at 260 nm from the grown Al0.9Ga0.1N-deltaGaN QW with a full width at half maximum of 12 nm, which shows that the demonstrated QW would be promising for high-efficiency UV LEDs.
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Cheng Liu, Kevin Lee, S. M. Islam, Huili Xing, Debdeep Jena, Jing Zhang, "Demonstration of AlGaN-delta-GaN QW by plasma-assisted molecular beam epitaxy for 260-nm ultraviolet light emitting diodes," Proc. SPIE 10532, Gallium Nitride Materials and Devices XIII, 105320W (23 February 2018);