Matthias BELLOEIL Croissance par épitaxie par jets moléculaires et caractérisation optique d ...

269 Pages·2017·13.47 MB·French

THÈSE
Pour obtenir le grade de
DOCTEUR DE LA
COMMUNAUTÉ UNIVERSITÉ GRENOBLE ALPES
Spécialité : PHYSIQUE DES MATERIAUX
Arrêté ministériel : 25 mai 2016
Présentée par
Matthias BELLOEIL
Thèse dirigée par Bruno DAUDIN, CEA
et co-dirigée par Bruno GAYRAL, CEA
préparée au sein du Laboratoire PHotonique, ELectronique et
Ingéniérie QuantiqueS
dans l'École Doctorale Physique
Croissance par épitaxie par jets moléculaires
et caractérisation optique d'hétérostructures
de nanofils GaN/AlGaN émettant dans
l'ultraviolet
Molecular beam epitaxy growth and optical
characterization of GaN/AlGaN nanowire
heterostructures emitting in the ultraviolet
Thèse soutenue publiquement le 12 mai 2017,
devant le jury composé de :
Monsieur ENRIQUE CALLEJA PARDO
PROFESSEUR, UNIV. POLYTECHNIQUE DE MADRID - ESPAGNE,
Rapporteur
Monsieur RAPHAËL BUTTE
MAITRE D'ENSEIGNEMENT ET DE RECHERCHE, ECOLE POLYTECH.
FEDERALE LAUSANNE SUISSE, Rapporteur
Monsieur PIERRE LEFEBVRE
DIRECTEUR DE RECHERCHE, CNRS DELEGATION LANGUEDOC-
ROUSSILLON, Examinateur
Monsieur JOËL LEYMARIE
PROFESSEUR, UNIV. BLAISE PASCAL, CLERMONT-FERRAND,
Examinateur
Monsieur HUBERT RENEVIER
PROFESSEUR, GRENOBLE INP, Président

Contents

Contents ................................................................................................................................................... 1
Acknowledgements ................................................................................................................................. 5
Main acronyms ........................................................................................................................................ 7
0. Introduction ................................................................................................................................... 10
0.1 Brief history of III-Nitride semiconductor research: from prehistory to the recent interest for
nanowires .......................................................................................................................................... 10
0.2 Context and motivations of the present research ................................................................... 12
0.3 Organization of the manuscript ............................................................................................. 15
0.4 Collaborations ....................................................................................................................... 15
1. Properties and growth of standard III-Nitride semiconductors ..................................................... 17
1.0 Introduction ........................................................................................................................... 17
1.1 Structural properties of III-Nitride semiconductors .............................................................. 17
1.1.1 Crystal structures of nitride materials ............................................................................ 17
1.1.2 Polarity in wurtzite nitrides ........................................................................................... 21
1.1.3 Spontaneous and piezoelectric polarization in wurtzite nitrides ................................... 22
1.2 Electronic properties of III-Nitride semiconductors .............................................................. 23
1.2.1 Band structure of bulk wurtzite III-Nitride binary crystals ........................................... 23
1.2.1.1 Bandgap of bulk wurtzite nitride binary crystals....................................................... 23
1.2.1.2 Other electronic transitions in bulk wurtzite nitride binaries .................................... 26
1.2.1.3 Effect of external parameters on the band structure of bulk nitride binaries ............. 31
1.2.2 Peculiarities of nitride ternary alloys ............................................................................. 34
1.2.2.1 Bandgap of ternary alloys .......................................................................................... 34
1.2.2.2 Broadening of emission for nitride ternary alloys ..................................................... 35
1.2.2.3 Stokes shift in nitride ternary alloys .......................................................................... 36
1.2.3 Effect of the dimensionality of nitride objects .............................................................. 38
1.2.3.1 Effects intrinsic to carrier quantum confinement in nitrides ..................................... 38
1.2.3.2 A consequence of the nitride peculiar polarization: the quantum-confined Stark effect
(QCSE) ................................................................................................................................... 41
1.2.3.3 The case of nitride nanowires .................................................................................... 43
1.2.3.4 Effect of excitation in nitride quantum heterostructures ........................................... 45
1.3 Growth of III-Nitride semiconductors ................................................................................... 48
1.3.1 Main existing epitaxial growth techniques .................................................................... 49
1.3.2 Main epitaxial growth mechanisms ............................................................................... 50
1.3.2.1 Main kinetic and surface phenomena ........................................................................ 50
1.3.2.2 Strain relaxation mechanisms .................................................................................... 51
1
Contents

1.3.2.3 Main epitaxial growth modes .................................................................................... 53
2. Experimental methods ................................................................................................................... 56
2.0 Introduction ........................................................................................................................... 56
2.1 Our growth technique: plasma-assisted molecular beam epitaxy (PA-MBE) ....................... 56
2.1.1 Presentation of the molecular beam epitaxy setup ........................................................ 56
2.1.1.1 The molecular beam epitaxy chamber ....................................................................... 56
2.1.1.2 The effusion and plasma cells ................................................................................... 57
2.1.1.3 The regulation of sample temperature ....................................................................... 58
2.1.1.4 In situ monitoring with reflection high energy electron diffraction (RHEED) ......... 60
2.1.2 Preparation of substrates and calibrations ..................................................................... 63
2.1.2.1 Preparation of substrates............................................................................................ 63
2.1.2.2 RHEED calibration of growth temperature with a Si (111) wafer ............................ 64
2.1.2.3 RHEED calibration of atomic fluxes ......................................................................... 67
2.1.3 GaN nanowire growth ................................................................................................... 69
2.1.3.1 GaN nanowire growth on Si (111) ............................................................................ 69
2.1.3.2 GaN nanowire growth on AlN buffer ........................................................................ 73
2.1.4 Al Ga N nanowire growth ........................................................................................... 74
x 1-x
2.1.4.1 AlGaN nanowire growth peculiarities ....................................................................... 74
2.1.4.2 Additional calibration for GaN and Al Ga N nanowire growth .............................. 77
x 1-x
2.2 Structural characterization techniques ................................................................................... 82
2.2.1 Electron microscopy ...................................................................................................... 82
2.2.1.1 Scanning electron microscopy (SEM) ....................................................................... 85
2.2.1.2 Scanning transmission electron microscopy (STEM) ............................................... 86
2.2.1.3 Energy-dispersive X-ray (EDX) ................................................................................ 87
2.2.2 X-ray diffraction (XRD) ................................................................................................ 88
2.2.3 Atomic-force microscopy (AFM) .................................................................................. 93
2.3 Optical characterization techniques ....................................................................................... 95
2.3.1 Photoluminescence (PL) ................................................................................................ 96
2.3.1.1 Photoluminescence with a continuous-wave laser excitation (CW-PL) .................... 96
2.3.1.2 Typical continuous-wave photoluminescence spectra of high-structural quality
nitride binary nanowires grown by molecular beam epitaxy .................................................... 98
2.3.1.3 Time-resolved photoluminescence (TRPL)............................................................. 102
2.3.1.4 Photon correlation experiments (HBT) ................................................................... 104
2.3.2 Cathodoluminescence (CL) ......................................................................................... 106
2.3.2.1 Cathodoluminescence in a SEM microscope .......................................................... 107
2.3.2.2 Cathodoluminescence in a STEM microscope ........................................................ 108
2.3.3 Raman spectroscopy .................................................................................................... 108
3. Investigation of carrier localization in Al Ga N nanowires ...................................................... 111
x 1-x
2
Contents

3.0 Introduction ......................................................................................................................... 111
3.1 Growth and basic structural properties of investigated AlGaN nanowire sections ............. 114
3.2 Optical properties of AlGaN nanowire sections .................................................................. 118
3.2.1 Average luminescence of as-grown AlGaN nanowires grown in various conditions . 118
3.2.2 Luminescence of single AlGaN nanowires grown in various conditions .................... 126
3.2.3 Evidence of a quantum-dot like behavior for localization centers .............................. 131
3.2.4 Attribution of the quantum dot-like behavior to compositional fluctuations in AlGaN
nanowires .................................................................................................................................... 134
3.2.5 Confirmation of the quantum-dot like behavior through power-dependent
photoluminescence experiments .................................................................................................. 138
3.2.6 Micro-photoluminescence dynamics of AlGaN nanowires ......................................... 143
3.2.7 Localization attributed to compositional fluctuations at very short scale. .................. 151
3.3 Additional discussion, conclusion and prospects of the chapter ......................................... 159
3.3.1 Macro-structural properties of AlGaN nanowire sections. .......................................... 159
3.3.2 Micro-optical properties of AlGaN nanowire sections. ............................................... 160
4. Another step towards UV-LEDs: study of Al Ga N nanowire pn junctions ............................. 162
x 1-x
4.0 Introduction ......................................................................................................................... 162
4.1 Growth conditions of investigated doped Al Ga N and AlN nanowire samples .............. 165
x 1-x
4.2 Structural properties of Al Ga N nanowire pn junctions .................................................. 168
x 1-x
4.2.1 Highlighting AlGaN nanowire pn junctions through structural characterization ........ 168
4.2.2 Peculiarities of AlN nanowire pn junctions ................................................................. 177
4.3 Optical signature of Al Ga N nanowire pn junctions ........................................................ 182
x 1-x
4.3.1 Luminescence of as-grown ensembles of doped Al Ga N nanowires ....................... 182
x 1-x
4.3.2 Investigation at smaller scale of dispersed Al Ga N nanowire pn junctions ............. 188
x 1-x
4.4 Additional discussion, conclusion and prospects of the chapter ......................................... 198
General conclusion and prospects ....................................................................................................... 200
Investigation of carrier localization in Al Ga N nanowires .......................................................... 200
x 1-x
Study of Al Ga N nanowire pn junctions ...................................................................................... 201
x 1-x
Annexes ............................................................................................................................................... 203
Annex 1: Crystallography in hexagonal systems ............................................................................ 203
Annex 1.1 Miller notations for hexagonal structures .................................................................. 203
Annex 1.2 Characteristic distances and angles in the hexagonal symmetry ............................... 205
Annex 1.3 Hexagonal cell reduction ........................................................................................... 206
Annex 2: Resonant (anomalous) X-ray diffraction ......................................................................... 207
Annex 2.0: Introduction to anomalous X-ray diffraction. ........................................................... 207
Annex 2.1: Basics of resonant X-ray diffraction formalism ....................................................... 209
Annex 2.2: DAFS formalism specific to the assessment of AlGaN polarity and average alloy
composition ................................................................................................................................. 211
3
Contents

Annex 2.3: DAFS formalism peculiar to the extended fine structure analysis ........................... 213
Annex 2.4: Samples investigated by anomalous X-ray diffraction ............................................. 216
Annex 2.5: Simultaneous determination of the polarity and average Al composition of AlGaN
NWs through DAFS spectroscopy .............................................................................................. 220
Annex 2.6: Preliminary overview of the extended fine structure region ..................................... 225
Annex 2.7: Conclusion and prospects ......................................................................................... 228
Summary in French ............................................................................................................................. 229
Bibliography ........................................................................................................................................ 238

4
Acknowledgements

On the 25th of November 2013, I started my PhD at CEA Grenoble. After many samples grown
and analyzed with varying degrees of success, it comes to an end. Therefore, now is the time to thank
all the people whom I have interacted with and who supported me during these 3 years. I apologize in
advance to those I may have inadvertently forgotten in the following.
First of all, I would like to express my gratitude to my supervisors, Bruno GAYRAL and Bruno
DAUDIN, for their guidance and advices as well as for giving me the opportunity to be a part of their
nitride materials research team within the INAC/NPSC laboratory.
I then warmly thank all the members of the jury for having accepted to assess my work: Enrique
CALLEJA and Raphaël BUTTÉ for the reports, Joël LEYMARIE, Hubert RENEVIER and Pierre
LEFEBVRE for the reviews.
I also sincerely thank all our collaborators external to INAC: Hubert RENEVIER for supervising
the resonant X-ray diffraction experiments at Synchrotron and for helping me process the data, Ana
CROS for Raman and Kelvin probe force microscopy characterizations, Mathieu KOCIAK and Luis
TIZEI for cathodoluminescence experiments, as well as Pierre LEFEBVRE, Thierry GUILLET, Pierre
VALVIN, and Christelle BRIMONT for their warm welcome at Montpellier and for the time-resolved
photoluminescence experiments.
As for internal collaborators, special thanks to Yoann CURE, Yann GENUIST and Didier
BOILOT for technical support on the molecular beam epitaxy machine, especially during the second
half of my PhD which was particularly challenging given the number of required interventions. I also
thank Nicolas MOLLARD and Eric ROBIN for their training and advices on electron microscopy
techniques, Fabrice DONATINI for his training on the cathodoluminescence setup at Neel Institute,
Edith BELLET-AMALRIC for her training and discussions regarding X-ray diffraction, Lynda
AMICHI and Catherine BOUGEROL for the electron microscopy and atom probe tomography
experiments, Joël BLEUSE for his help on the time-resolved photoluminescence setup of the
5
Acknowledgements

laboratory, Joël EYMERY and Christophe DURAND for their kindness and fruitful discussion, and
Jean DUSSAUD for his general support.
Thanks to all PhD and post-doctoral students who are or were in the same boat. First, the team
members: Thomas AUZELLE for having trained me on the molecular beam epitaxy setup and for
helpful discussions, Xin ZHANG for his support, Zhihua FANG who shared my office and has
tolerated me for three years, which is not always easy, as well as the two last PhD students whom I
wish good luck, Madalina SILADIE, who will pursue the work on AlGaN nanowires, and Marion
GRUART. Next, the other students at NPSC: Anna, Caroline, Agnès, Thibault, Damien, Samuel,
Emanuel, Tobias, Jonas, Mark, Sirona, Mathieu, Akhil, Amine, Maria, David, Daria, Siew li and
others for livening things up at and out of the lab. Last, I do not forget all the other students met at
CEA, or during GANEX meetings and other events: special thanks to Fabien, Louis, Maxime,
Aurélien, Damien, and Gautier for their sense of humor and kindness.
Finally, I would like to thank my family, especially my parents and my brothers, as well as my
close friends who have supported me for all these years, whatever the challenges in life.

6
Main acronyms

III-N: III-Nitride
A°X: Acceptor-bound eXciton
AFM: Atomic Force Microscopy
AlGaN: Aluminum Gallium Nitride
AlInN: Aluminum Indium Nitride
AlN: Aluminum Nitride
BL: Blue Luminescence (band)
BF: Bright Field
CCD: Charge-Coupled Device
CF: Crystal-Field
CL: Cathodoluminescence
CPD: Contact Potential Difference
CVD: Chemical Vapor Deposition
CW: Continuous-Wave
D°X: Donor-bound eXciton
DAP: Donor-Acceptor Pair
DF: Dark Field
(E)DAFS: (Extended) Diffraction Anomalous Fine Structure
EDX: Energy-Dispersive X-ray
EQE: External Quantum Efficiency
ESRF: European Synchrotron Radiation Facility
(E)XAFS: (Extended) X-ray Absorption Fine Structure
FM: Frank-van der Merwe
FWHM: Full Width at Half Maximum
7
Main acronyms

FX: Free eXciton
GaN: Gallium Nitride
(HA)ADF: (High-Angle) Annular Dark-Field
HBT: Hanbury Brown and Twiss
HEMT: High Electron Mobility Transistor
HF: HydroFluoric acid
HR: High-Resolution
HVPE: Hybrid Vapor-Phase Epitaxy
InGaN: Indium Gallium Nitride
InN: Indium Nitride
IQE: Internal Quantum Efficiency
IR: InfraRed
KPFM: Kelvin Probe Force Microscopy
LD: Laser Diode
LED: Light-Emitting Diode
LO: Longitudinal Optical
MAD: Multi-wavelength Anomalous Diffraction
MD: Misfit Dislocation
ML: MonoLayer
MOVPE: MetalOrganic Vapor Phase Epitaxy
NBE: Near Band Edge
NID: Non-Intentionally Doped
NW: NanoWire
(µ-)PL: (micro-)PhotoLuminescence
(PA-)MBE: (Plasma-Assisted) Molecular Beam Epitaxy
PMT: Photomultiplicator
8