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Effect of substrate misorientation angle on the structural properties of N-polar GaN grown by hot-wall MOCVD on 4H-SiC(000(1)over-bar)

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Název: Effect of substrate misorientation angle on the structural properties of N-polar GaN grown by hot-wall MOCVD on 4H-SiC(000(1)over-bar)
Autoři: Zhang, Hengfang, Chen, Jr-Tai, Papamichail, Alexis, Persson, Ingemar, Tran, Dat, Paskov, Plamen, Darakchieva, Vanya
Zdroj: Journal of Crystal Growth. 651
Témata: N-polar GaN, epitaxial growth, SiC substrate misorientation angle, Multi-step temperature growth, MOCVD
Popis: The effects of substrate misorientation angle direction and degree on the structural properties of N-polar GaN grown by a novel multi-step temperature epitaxial approach using hot-wall metal-organic chemical vapor deposition (MOCVD) on 4H-SiC (000 (1) over bar) substrates is investigated. The surface morphology and X-ray diffraction (XRD) rocking curves (RCs) for both symmetric and asymmetric Bragg peaks of the multi-step temperature N-polar GaN are compared to a material obtained in a two-step temperature process. In the latter the temperature in the second step was varied so that it corresponds to the growth temperatures in each of the steps of the multi-step process. Different step-flow patterns are obtained on the substrates with a misorientation angle of 4 degrees depending on whether its direction is towards the a-plane or the m-plane. In contrast, fora misorientation angle of 1 degrees towards the m-plane, the surface morphology of N-polar GaN is dominated by hexagonal hillocks when using the 2-step temperature process and a step meandering growth mode is observed when employing the multi-step temperature process. These results are discussed and explained in terms of kinetic and thermodynamic considerations. As the growth temperature of the GaN layer in the 2-step temperature process increases from 950 degrees C to 1100 degrees C, the surface roughness and RCs widths decrease for the three types of substrates indicating improved crystal quality at higher temperature. The multi-step epitaxial approach is shown to be beneficial for achieving smooth surface morphology and low defect density of N-polar GaN layers grown on C-face SiC substrates with a misorientation angle of 4 degrees and an RMS value of 1.5 nm over an area of 20 mu m x 20 mu m is attained when the substrate mis-cut is towards the m-plane.
Popis souboru: electronic
Přístupová URL adresa: https://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-210437
https://liu.diva-portal.org/smash/get/diva2:1921430/FULLTEXT01.pdf
Databáze: SwePub
Popis
Abstrakt:The effects of substrate misorientation angle direction and degree on the structural properties of N-polar GaN grown by a novel multi-step temperature epitaxial approach using hot-wall metal-organic chemical vapor deposition (MOCVD) on 4H-SiC (000 (1) over bar) substrates is investigated. The surface morphology and X-ray diffraction (XRD) rocking curves (RCs) for both symmetric and asymmetric Bragg peaks of the multi-step temperature N-polar GaN are compared to a material obtained in a two-step temperature process. In the latter the temperature in the second step was varied so that it corresponds to the growth temperatures in each of the steps of the multi-step process. Different step-flow patterns are obtained on the substrates with a misorientation angle of 4 degrees depending on whether its direction is towards the a-plane or the m-plane. In contrast, fora misorientation angle of 1 degrees towards the m-plane, the surface morphology of N-polar GaN is dominated by hexagonal hillocks when using the 2-step temperature process and a step meandering growth mode is observed when employing the multi-step temperature process. These results are discussed and explained in terms of kinetic and thermodynamic considerations. As the growth temperature of the GaN layer in the 2-step temperature process increases from 950 degrees C to 1100 degrees C, the surface roughness and RCs widths decrease for the three types of substrates indicating improved crystal quality at higher temperature. The multi-step epitaxial approach is shown to be beneficial for achieving smooth surface morphology and low defect density of N-polar GaN layers grown on C-face SiC substrates with a misorientation angle of 4 degrees and an RMS value of 1.5 nm over an area of 20 mu m x 20 mu m is attained when the substrate mis-cut is towards the m-plane.
ISSN:00220248
18735002
DOI:10.1016/j.jcrysgro.2024.127971