High-quality N-polar GaN optimization by multi-step temperature growth process
(2023) In Journal of Crystal Growth 603.- Abstract
- We report growth optimization of Nitrogen (N)-polar GaN epitaxial layers by hot-wall metal–organic vapor phase epitaxy on 4H-SiC (000) with a misorientation angle of 4° towards the [110] direction. We find that when using a 2-step temperature process for the N-polar GaN growth, step bunching is persistent for a wide range of growth rates (7 nm/min to 49 nm/min) and V/III ratios (251 to 3774). This phenomenon is analyzed in terms of anisotropic step-flow growth and the Ehrlich–Schwöebel barrier, and their effects on the surface step height and step width. The N-polar GaN growth is further optimized by using 3-step and 4-step temperature processes and the layers are compared to those using the 2-step temperature process in terms of surface... (More)
- We report growth optimization of Nitrogen (N)-polar GaN epitaxial layers by hot-wall metal–organic vapor phase epitaxy on 4H-SiC (000) with a misorientation angle of 4° towards the [110] direction. We find that when using a 2-step temperature process for the N-polar GaN growth, step bunching is persistent for a wide range of growth rates (7 nm/min to 49 nm/min) and V/III ratios (251 to 3774). This phenomenon is analyzed in terms of anisotropic step-flow growth and the Ehrlich–Schwöebel barrier, and their effects on the surface step height and step width. The N-polar GaN growth is further optimized by using 3-step and 4-step temperature processes and the layers are compared to those using the 2-step temperature process in terms of surface morphology and defect densities. It is shown that a significantly improved surface morphology with a root mean square of 1.4 nm and with low dislocation densities (screw dislocation density of 2.8 × 108 cm−2 and edge dislocation density of 1.3 × 109 cm−2) can be achieved for 4-step temperature process. The optimized growth conditions allow to overcome the step-bunching problem. The results are further discussed in view of Ga supersaturation and a general growth strategy for high-quality N-polar GaN growth is proposed. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/2bdff883-54b9-491d-b91b-86541596472a
- author
- Zhang, Hengfang ; Chen Jr., Tai ; Papamichail, Alexis ; Persson, Ingemar ; Paskov, Plamen P. and Darakchieva, Vanya LU
- organization
- publishing date
- 2023-02
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- N-polar GaN, MOCVD, epitaxial growth, epitaxial III-nitride, surface morphology, 2-step temperature process, Ga supersaturation
- in
- Journal of Crystal Growth
- volume
- 603
- article number
- 127002
- publisher
- Elsevier
- external identifiers
-
- scopus:85143858994
- ISSN
- 0022-0248
- DOI
- 10.1016/j.jcrysgro.2022.127002
- language
- English
- LU publication?
- yes
- id
- 2bdff883-54b9-491d-b91b-86541596472a
- date added to LUP
- 2023-02-12 14:48:06
- date last changed
- 2023-11-21 09:45:48
@article{2bdff883-54b9-491d-b91b-86541596472a,
abstract = {{We report growth optimization of Nitrogen (N)-polar GaN epitaxial layers by hot-wall metal–organic vapor phase epitaxy on 4H-SiC (000) with a misorientation angle of 4° towards the [110] direction. We find that when using a 2-step temperature process for the N-polar GaN growth, step bunching is persistent for a wide range of growth rates (7 nm/min to 49 nm/min) and V/III ratios (251 to 3774). This phenomenon is analyzed in terms of anisotropic step-flow growth and the Ehrlich–Schwöebel barrier, and their effects on the surface step height and step width. The N-polar GaN growth is further optimized by using 3-step and 4-step temperature processes and the layers are compared to those using the 2-step temperature process in terms of surface morphology and defect densities. It is shown that a significantly improved surface morphology with a root mean square of 1.4 nm and with low dislocation densities (screw dislocation density of 2.8 × 10<sup>8</sup> cm<sup>−2</sup> and edge dislocation density of 1.3 × 10<sup>9</sup> cm<sup>−2</sup>) can be achieved for 4-step temperature process. The optimized growth conditions allow to overcome the step-bunching problem. The results are further discussed in view of Ga supersaturation and a general growth strategy for high-quality N-polar GaN growth is proposed.}},
author = {{Zhang, Hengfang and Chen Jr., Tai and Papamichail, Alexis and Persson, Ingemar and Paskov, Plamen P. and Darakchieva, Vanya}},
issn = {{0022-0248}},
keywords = {{N-polar GaN; MOCVD; epitaxial growth; epitaxial III-nitride; surface morphology; 2-step temperature process; Ga supersaturation}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Journal of Crystal Growth}},
title = {{High-quality N-polar GaN optimization by multi-step temperature growth process}},
url = {{http://dx.doi.org/10.1016/j.jcrysgro.2022.127002}},
doi = {{10.1016/j.jcrysgro.2022.127002}},
volume = {{603}},
year = {{2023}},
}