From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides

Sourish Banerjee

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

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Abstract

To continue the miniaturization trend of Silicon (Si)-based microelectronic devices in an era when we have almost fully-exploited the physical capabilities of Si, other semiconductors such as gallium nitride (GaN) and aluminium nitride (AlN) (collectively (Al)GaN) are currently being investigated. These can potentially complement Si, since in their monocrystalline form, have superior material properties to Si. Examples include direct and wider bandgap, high electron mobility and high breakdown field. Thus, combining the mature Si-based process technology with such superior (Al)GaN material properties on one platform enables microelectronic devices, in accordance with the ‘More-than-Moore’ philosophy. Exploring polycrystalline and thin film (i.e., sub-micron) (Al)GaN must also be pursued, since that broadens their applications; enabling utilization in sensors, thin film transistors (TFT), as passivation layers, etc. Atomic layer deposition (ALD) is a highly relevant technique for (Al)GaN, since the technique promises atomic-level thickness control, coupled with superb film conformality and spatial uniformity. Reports of (Al)GaN ALD are only appearing recently in the literature, suggesting the increasing relevance of this field.

This thesis investigated ALD of polycrystalline (Al)GaN, using conventional Si-technology and industrially accepted precursors. A variety of activation techniques, from thermal, to plasma, and the novel hot-wire activation were explored. Some important obtained research results were: (a) Identification of a chemical route which enables pure thermal ALD of GaN, (b) Preparation of novel GaCN composite layers with high refractive indices, (c) Selectively depositing GaN on specially-terminated substrates, (d) Tuning (Al)GaN polycrystallinity and optical properties with plasma composition and investigating the underlying causes, (e) Investigating the role of precursor-generated radicals on (Al)GaN growth, and (f) Identifying the discontinuous nature of sub-10 nm AlN with electrical and optical techniques. In conclusion, the results obtained and the suggested future work are expected to advance the state-of-the-art of Al(GaN) ALD.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Twente
Supervisors/Advisors
  • Gravesteijn, Dirk J, Supervisor
  • Kovalgin, Alexey Y., Supervisor
Award date11 Sep 2019
Place of PublicationEnschede
Publisher
Print ISBNs978-90-365-4825-0
DOIs
Publication statusPublished - 11 Sep 2019

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gallium nitrides
aluminum nitrides
atomic layer epitaxy
silicon
microelectronics
activation
plasma composition
theses
miniaturization
thin films
electron mobility
complement
passivity
transistors
platforms
breakdown
tuning
routes
wire
refractivity

Cite this

Banerjee, Sourish . / From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides. Enschede : University of Twente, 2019. 201 p.
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title = "From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides",
abstract = "To continue the miniaturization trend of Silicon (Si)-based microelectronic devices in an era when we have almost fully-exploited the physical capabilities of Si, other semiconductors such as gallium nitride (GaN) and aluminium nitride (AlN) (collectively (Al)GaN) are currently being investigated. These can potentially complement Si, since in their monocrystalline form, have superior material properties to Si. Examples include direct and wider bandgap, high electron mobility and high breakdown field. Thus, combining the mature Si-based process technology with such superior (Al)GaN material properties on one platform enables microelectronic devices, in accordance with the ‘More-than-Moore’ philosophy. Exploring polycrystalline and thin film (i.e., sub-micron) (Al)GaN must also be pursued, since that broadens their applications; enabling utilization in sensors, thin film transistors (TFT), as passivation layers, etc. Atomic layer deposition (ALD) is a highly relevant technique for (Al)GaN, since the technique promises atomic-level thickness control, coupled with superb film conformality and spatial uniformity. Reports of (Al)GaN ALD are only appearing recently in the literature, suggesting the increasing relevance of this field.This thesis investigated ALD of polycrystalline (Al)GaN, using conventional Si-technology and industrially accepted precursors. A variety of activation techniques, from thermal, to plasma, and the novel hot-wire activation were explored. Some important obtained research results were: (a) Identification of a chemical route which enables pure thermal ALD of GaN, (b) Preparation of novel GaCN composite layers with high refractive indices, (c) Selectively depositing GaN on specially-terminated substrates, (d) Tuning (Al)GaN polycrystallinity and optical properties with plasma composition and investigating the underlying causes, (e) Investigating the role of precursor-generated radicals on (Al)GaN growth, and (f) Identifying the discontinuous nature of sub-10 nm AlN with electrical and optical techniques. In conclusion, the results obtained and the suggested future work are expected to advance the state-of-the-art of Al(GaN) ALD.",
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year = "2019",
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Banerjee, S 2019, 'From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides', Doctor of Philosophy, University of Twente, Enschede. https://doi.org/10.3990/1.9789036548250

From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides. / Banerjee, Sourish .

Enschede : University of Twente, 2019. 201 p.

Research output: ThesisPhD Thesis - Research UT, graduation UTAcademic

TY - THES

T1 - From radical-enhanced to pure thermal ALD of gallium and aluminium nitrides

AU - Banerjee, Sourish

PY - 2019/9/11

Y1 - 2019/9/11

N2 - To continue the miniaturization trend of Silicon (Si)-based microelectronic devices in an era when we have almost fully-exploited the physical capabilities of Si, other semiconductors such as gallium nitride (GaN) and aluminium nitride (AlN) (collectively (Al)GaN) are currently being investigated. These can potentially complement Si, since in their monocrystalline form, have superior material properties to Si. Examples include direct and wider bandgap, high electron mobility and high breakdown field. Thus, combining the mature Si-based process technology with such superior (Al)GaN material properties on one platform enables microelectronic devices, in accordance with the ‘More-than-Moore’ philosophy. Exploring polycrystalline and thin film (i.e., sub-micron) (Al)GaN must also be pursued, since that broadens their applications; enabling utilization in sensors, thin film transistors (TFT), as passivation layers, etc. Atomic layer deposition (ALD) is a highly relevant technique for (Al)GaN, since the technique promises atomic-level thickness control, coupled with superb film conformality and spatial uniformity. Reports of (Al)GaN ALD are only appearing recently in the literature, suggesting the increasing relevance of this field.This thesis investigated ALD of polycrystalline (Al)GaN, using conventional Si-technology and industrially accepted precursors. A variety of activation techniques, from thermal, to plasma, and the novel hot-wire activation were explored. Some important obtained research results were: (a) Identification of a chemical route which enables pure thermal ALD of GaN, (b) Preparation of novel GaCN composite layers with high refractive indices, (c) Selectively depositing GaN on specially-terminated substrates, (d) Tuning (Al)GaN polycrystallinity and optical properties with plasma composition and investigating the underlying causes, (e) Investigating the role of precursor-generated radicals on (Al)GaN growth, and (f) Identifying the discontinuous nature of sub-10 nm AlN with electrical and optical techniques. In conclusion, the results obtained and the suggested future work are expected to advance the state-of-the-art of Al(GaN) ALD.

AB - To continue the miniaturization trend of Silicon (Si)-based microelectronic devices in an era when we have almost fully-exploited the physical capabilities of Si, other semiconductors such as gallium nitride (GaN) and aluminium nitride (AlN) (collectively (Al)GaN) are currently being investigated. These can potentially complement Si, since in their monocrystalline form, have superior material properties to Si. Examples include direct and wider bandgap, high electron mobility and high breakdown field. Thus, combining the mature Si-based process technology with such superior (Al)GaN material properties on one platform enables microelectronic devices, in accordance with the ‘More-than-Moore’ philosophy. Exploring polycrystalline and thin film (i.e., sub-micron) (Al)GaN must also be pursued, since that broadens their applications; enabling utilization in sensors, thin film transistors (TFT), as passivation layers, etc. Atomic layer deposition (ALD) is a highly relevant technique for (Al)GaN, since the technique promises atomic-level thickness control, coupled with superb film conformality and spatial uniformity. Reports of (Al)GaN ALD are only appearing recently in the literature, suggesting the increasing relevance of this field.This thesis investigated ALD of polycrystalline (Al)GaN, using conventional Si-technology and industrially accepted precursors. A variety of activation techniques, from thermal, to plasma, and the novel hot-wire activation were explored. Some important obtained research results were: (a) Identification of a chemical route which enables pure thermal ALD of GaN, (b) Preparation of novel GaCN composite layers with high refractive indices, (c) Selectively depositing GaN on specially-terminated substrates, (d) Tuning (Al)GaN polycrystallinity and optical properties with plasma composition and investigating the underlying causes, (e) Investigating the role of precursor-generated radicals on (Al)GaN growth, and (f) Identifying the discontinuous nature of sub-10 nm AlN with electrical and optical techniques. In conclusion, the results obtained and the suggested future work are expected to advance the state-of-the-art of Al(GaN) ALD.

U2 - 10.3990/1.9789036548250

DO - 10.3990/1.9789036548250

M3 - PhD Thesis - Research UT, graduation UT

SN - 978-90-365-4825-0

PB - University of Twente

CY - Enschede

ER -