N. Zainal^1,2, S. Hagedorn¹, C. Netzel¹, T. Kolbe¹, and M. Weyers¹

Published in:

phys. stat. sol. (a), vol. 221, no. 7, pp. 2300897, doi:10.1002/pssa.202300897 (2024).

Abstract:

This study explores the impact of Si doping on the material properties of high-temperature annealed (HTA) Al_0.71Ga_0.29N layers, which are grown on AlN/sapphire templates. The AlGaN layers are doped with Si by applying different IV/III ratios during epitaxial growth and compared to undoped Al_0.71Ga_0.29N. Before HTA, the threading dislocation density (TDD) for all samples is about 6.0 × 10⁹ cm^-2. After HTA, the Si-doped AlGaN grown with the highest IV/III ratio of 3.6 × 10⁴ shows the lowest TDD of 1.2 × 10⁹ cm^-2. Secondary ion mass spectrometry depth profiles reveal an accelerated Ga diffusion from the doped AlGaN into the AlN buffer layer compared to undoped AlGaN. This suggests that the Ga diffusion process is mediated by Si diffusion. Consequently, the Ga diffusion leads to a decrease in the Ga mole fraction of annealed Si-doped AlGaN. Furthermore, strain relaxation is higher for the Si-doped AlGaN than for the undoped AlGaN, before and after HTA. The results from this study suggest that Si doping can be a new promising approach in enhancing the quality of HTA-AlGaN as a useful template for the growth of UV LED heterostructures.

Keywords:

Ga diffusion, Ga removal/desorption, high-temperature annealing, metalorganic vapor phase epitaxy, Si-doped AlGaN

© 2024 The Authors. physica status solidi (a) applications and materials science published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.
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