Overcoming the excessive compressive strain in AlGaN epitaxy by introducinghigh Si-doping in AlN templates

C.-Y. Huang1, S. Walde2, C.-L. Tsai1, C. Netzel2, H.-H. Liu1, S. Hagedorn2, Y.-R. Wu1,3, Y.-K. Fu1, and M. Weyers2

Published in:

Jpn. J. Appl. Phys., vol. 59, no. 7, pp. 070904 (2020).

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The influence of compressive strain in high-quality AlN templates on the subsequent growth of AlGaN-based device layers was investigated. The AlN templates showed compressive strain of ∼-0.29% and threading dislocation densities (TDDs) below 6.5 × 108cm-2. By introducing high Si-doping in MOVPE-grown AlN, the compressive strain was relaxed while preserving the low TDD. By this method, the low TDD was transferred from the AlN template to the micron-thick n-Al0.63Ga0.37N. A 275 nm LED was demonstrated with a ∼2.5 times power enhancement than the same LED on conventional MOVPE-grown AlN template under low current injection. The maximum external quantum efficiency (EQE) was enhanced from 1.6% to 2.2% with an improved n-AlGaN.

1 Electronic and Optoelectronic System Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu, 31057, Taiwan
2 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Strasse 4, 12489 Berlin, Germany
3 Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan