Development of thick GaN and AlGaN drift layers for vertical power devices
(2023) PHYM03 20231Solid State Physics
Department of Physics
- Abstract
- High-quality, thick III-nitride epitaxial drift layers with controlled doping are
needed for next-generation highly efficient vertical power devices for a smart grid
applications and electrification of mobility. Achieving desirable material properties, such as low background impurity concentrations and reduced dislocation densities in combination with high growth rates, necessary for practical application present a challenge. In this work, metal-organic vapor phase epitaxy (MOVPE) is employed for the development of GaN and low-Al content AlGaN drift layers on GaN substrates.
GaN drift layers with controlled Si doping of 4.6×1016cm−3 and thicknesses of 5 μm and 10 μm were homoepitaxially grown utilizing a n+ (7.6×1018cm−3) 300 nm-thick... (More) - High-quality, thick III-nitride epitaxial drift layers with controlled doping are
needed for next-generation highly efficient vertical power devices for a smart grid
applications and electrification of mobility. Achieving desirable material properties, such as low background impurity concentrations and reduced dislocation densities in combination with high growth rates, necessary for practical application present a challenge. In this work, metal-organic vapor phase epitaxy (MOVPE) is employed for the development of GaN and low-Al content AlGaN drift layers on GaN substrates.
GaN drift layers with controlled Si doping of 4.6×1016cm−3 and thicknesses of 5 μm and 10 μm were homoepitaxially grown utilizing a n+ (7.6×1018cm−3) 300 nm-thick GaN nucleation layers. Smooth surface layer morphology with a surface roughness of 0.11 nm over 2 μm×2 μm area was demonstrated and the density of screw dislocations in the drift layers was found to be comparable to or better than that in the GaN substrate. In addition, the densities of edge dislocations, which are the predominant type of dislocations and are responsible for the undesired leakage currents, were decreased with respect to the substrate. At the optimised growth conditions, an industrially relevant growth rate of 2 μm/h was achieved, and background concentrations of C, H and O were limited to 1.1 × 1016cm−3, 3.4×1016cm−3 and 9.6×1014cm−3, respectively.
To enhance the Baliga figure of merit, 5 μm AlGaN drift layers with low Al content (7.28%) were grown on GaN substrates. A graded AlGaN buffer layer was developed to accommodate tensile strain, where both its thickness and doping were explored. We found that a 300 nm thick, n− doped, compositionally-graded AlGaN buffer layer enables crack-free drift layers with smooth surface morphology (surface roughness of 0.15 nm). As a next step the optimized GaN and AlGaN drift layers are being employed for the fabrication of FIN field effect transistors. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9134949
- author
- Dhora, Andri LU
- supervisor
- organization
- course
- PHYM03 20231
- year
- 2023
- type
- H2 - Master's Degree (Two Years)
- subject
- language
- English
- id
- 9134949
- date added to LUP
- 2023-08-24 16:12:45
- date last changed
- 2023-10-15 03:43:48
@misc{9134949,
abstract = {{High-quality, thick III-nitride epitaxial drift layers with controlled doping are
needed for next-generation highly efficient vertical power devices for a smart grid
applications and electrification of mobility. Achieving desirable material properties, such as low background impurity concentrations and reduced dislocation densities in combination with high growth rates, necessary for practical application present a challenge. In this work, metal-organic vapor phase epitaxy (MOVPE) is employed for the development of GaN and low-Al content AlGaN drift layers on GaN substrates.
GaN drift layers with controlled Si doping of 4.6×1016cm−3 and thicknesses of 5 μm and 10 μm were homoepitaxially grown utilizing a n+ (7.6×1018cm−3) 300 nm-thick GaN nucleation layers. Smooth surface layer morphology with a surface roughness of 0.11 nm over 2 μm×2 μm area was demonstrated and the density of screw dislocations in the drift layers was found to be comparable to or better than that in the GaN substrate. In addition, the densities of edge dislocations, which are the predominant type of dislocations and are responsible for the undesired leakage currents, were decreased with respect to the substrate. At the optimised growth conditions, an industrially relevant growth rate of 2 μm/h was achieved, and background concentrations of C, H and O were limited to 1.1 × 1016cm−3, 3.4×1016cm−3 and 9.6×1014cm−3, respectively.
To enhance the Baliga figure of merit, 5 μm AlGaN drift layers with low Al content (7.28%) were grown on GaN substrates. A graded AlGaN buffer layer was developed to accommodate tensile strain, where both its thickness and doping were explored. We found that a 300 nm thick, n− doped, compositionally-graded AlGaN buffer layer enables crack-free drift layers with smooth surface morphology (surface roughness of 0.15 nm). As a next step the optimized GaN and AlGaN drift layers are being employed for the fabrication of FIN field effect transistors.}},
author = {{Dhora, Andri}},
language = {{eng}},
note = {{Student Paper}},
title = {{Development of thick GaN and AlGaN drift layers for vertical power devices}},
year = {{2023}},
}