Effect of substrate misorientation angle on the structural properties of N-polar GaN grown by hot-wall MOCVD on 4H-SiC(0001̄)
(2025) In Journal of Crystal Growth 651.- Abstract
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 (0001̄) 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... (More)
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 (0001̄) 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° depending on whether its direction is towards the a-plane or the m-plane. In contrast, for a misorientation angle of 1° 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 °C to 1100 °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° and an RMS value of 1.5 nm over an area of 20 μm × 20 μm is attained when the substrate mis-cut is towards the m-plane.
(Less)
- author
- Zhang, Hengfang ; Chen, Jr Tai ; Papamichail, Alexis ; Persson, Ingemar ; Tran, Dat Q. ; Paskov, Plamen P. and Darakchieva, Vanya LU
- organization
- publishing date
- 2025
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- epitaxial growth, MOCVD, Multi-step temperature growth, N-polar GaN, SiC substrate misorientation angle
- in
- Journal of Crystal Growth
- volume
- 651
- article number
- 127971
- publisher
- Elsevier
- external identifiers
-
- scopus:85210094818
- ISSN
- 0022-0248
- DOI
- 10.1016/j.jcrysgro.2024.127971
- language
- English
- LU publication?
- yes
- id
- 04050c59-08cf-4eb1-b935-ae5f1a109d30
- date added to LUP
- 2025-02-18 15:33:32
- date last changed
- 2025-04-04 14:03:01
@article{04050c59-08cf-4eb1-b935-ae5f1a109d30,
abstract = {{<p>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 (0001̄) 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° depending on whether its direction is towards the a-plane or the m-plane. In contrast, for a misorientation angle of 1° 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 °C to 1100 °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° and an RMS value of 1.5 nm over an area of 20 μm × 20 μm is attained when the substrate mis-cut is towards the m-plane.</p>}},
author = {{Zhang, Hengfang and Chen, Jr Tai and Papamichail, Alexis and Persson, Ingemar and Tran, Dat Q. and Paskov, Plamen P. and Darakchieva, Vanya}},
issn = {{0022-0248}},
keywords = {{epitaxial growth; MOCVD; Multi-step temperature growth; N-polar GaN; SiC substrate misorientation angle}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Journal of Crystal Growth}},
title = {{Effect of substrate misorientation angle on the structural properties of N-polar GaN grown by hot-wall MOCVD on 4H-SiC(0001̄)}},
url = {{http://dx.doi.org/10.1016/j.jcrysgro.2024.127971}},
doi = {{10.1016/j.jcrysgro.2024.127971}},
volume = {{651}},
year = {{2025}},
}