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GROWTH, OPTIMIZATION,AND CHARACTERIZATION OF TRANSITION METALNITRIDESAND TRANSITION METALOXIDES FOR ELECTRONIC
AND OPTICALAPPLICATIONS

Thesis
Submitted to
The School of Engineering of the UNIVERSITY OF DAYTON

In Partial Fulfillment of the Requirements for
The Degree of
Master of Science in Electro-Optics

By
Zachary Biegler

UNIVERSITY OF DAYTON
Dayton, Ohio December 2019
GROWTH, OPTIMIZATION, AND CHARACTERIZATION OF TRANSITION
METAL NITRIDES AND TRANSITION METAL OXIDES FOR ELECTRONIC AND
OPTICAL APPLICATIONS

Name: Biegler, Zachary Jay APPROVED BY:

Andrew Sarangan, Ph.D., P.E. Advisory Committee Chairman Professor
Amber Reed, Ph.D. Committee Member Materials Engineer

  • AFRL/RXAN
  • Department of Electro-Optics and Photonics

Partha Banerjee, Ph.D. Committee Member Professor Department of Electro-Optics and Photonics

Robert J. Wilkens, Ph.D., P.E. Associate Dean for Research and Innovation Professor
Eddy M. Rojas, Ph.D., M.A., P.E. Dean, School of Engineering

School of Engineering

ii
ABSTRACT
GROWTH, OPTIMIZATION, AND CHARACTERIZATION OF TRANSITION
METAL NITRIDES AND TRANSITION METAL OXIDES FOR ELECTRONIC AND
OPTICAL APPLICATIONS

Name: Biegler, Zachary J. University of Dayton

Advisor: Dr. Andrew Sarangan
The next generation of electronic and optical devices require high quality, crystalline materials in order to obtain relevant properties for novel devices. Two classes of materials offer unique material properties that can satisfy the requirements for next generation devices. These two classes of materials are the transition metal nitrides (TMNs) and transition metal oxides (TMOs). These materials offer electronic properties that range from conductive, metallic, materials to semiconducting and insulating materials. However, for many optical and electronic applications, the band structure and crystalline symmetries must be preserved. This work examines the growth and characterization of the TMN materials AlN and ScN as well as the TMO materials VO2 and TiO2. In all these materials, the crystalline structure plays and extremely important role in the desired properties. In addition, incorporation of other impurities can detrimentally impact the functionality of these film materials. In order to minimize the impurity incorporation and maintain the crystalline structure, the growth of AlN, ScN, VO2, and TiO2 films by various deposition techniques were examined and optimized. This allowed growth of high quality TMN and TMO materials that resulted in

iii characterization and optimization of the relevant optical, electronic, and structural properties and, somewhat, the degree to which these properties could be tuned through growth conditions.

iv

DEDICATION

This work is dedicated to my parents and siblings. v
ACKNOWLEDGMENTS
This work would not have been possible without the help and guidance from so many different people. My advisors Dr. Andrew Sarangan and Dr. Amber Reed both spent many hours helping me get into a field of study of which I was not familiar. Words cannot express how much their guidance and patience means to me. I also would like to thank Dr. Kurt Eyink, Dr. Tyson Back, Dr. John Centar, and Dr. David Look for all of their help taking data and discussing results obtained through the characterization of these films. Dr. Dean Brown provided COMSOL simulations of the magnetic fields in the unbalanced magnetron system. In addition, none of this work could have been possible without the help of Hadley Smith and Rachel Adams who helped with sample growth and XRD characterization of some of the TMN materials. Dr. Pengfei Guo was instrumental in the growth of VO2 by thermal oxidation. Last, but certainly not least, I want to thank Madelyn Hill for all of the AFM surface analysis that was performed in this work as well as Dr. Albert Hilton for the piezoelectric force microscopy measurements.
Additionally, none of the transition metal nitride work could have commenced without the support of AFOSR under the award number FA9550-17RYCOR490.

vi
TABLE OF CONTENTS
ABSTRACT....................................................................................................................... iii DEDICATION.................................................................................................................... v ACKNOWLEDGMENTS ................................................................................................. vi LIST OF FIGURES ............................................................................................................ x LIST OF ABBREVIATIONS AND NOTATIONS......................................................... xv CHAPTER 1 INTRODUCTION TO MATERIAL SYSTEMS......................................... 1
1.1 Transition Metal Nitrides ..................................................................................... 2
1.1.1 1.1.2 1.1.3
Titanium Nitride............................................................................................ 3 Scandium Nitride .......................................................................................... 4 Aluminum Nitride......................................................................................... 5
1.2 Transition Metal Oxides....................................................................................... 9
1.2.1 1.2.2
Vanadium Oxide........................................................................................... 9 Titanium Oxide........................................................................................... 12
CHAPTER 2 GROWTH SYSTEMS................................................................................ 15
2.1 DC Sputtering System........................................................................................ 15
2.1.1 2.1.2 2.1.3 2.1.4
Sputter Deposition ...................................................................................... 15 Reactive Sputtering..................................................................................... 17 Magnetron Sputtering ................................................................................. 18 Sputtering System....................................................................................... 21
2.2 Controllably-Unbalanced DC Reactive Magnetron Sputtering ......................... 22

vii

  • 2.2.2
  • Controllably-Unbalanced Sputtering System ............................................. 26

2.3 Ion Assisted Evaporation System....................................................................... 30
2.3.1 2.3.2 2.3.3
Thermal Evaporation .................................................................................. 31 Ion Assisted Evaporation ............................................................................ 33 IAD System................................................................................................. 34
CHAPTER 3 CHARACTERIZATION TECHNIQUES.................................................. 37
3.1 X-Ray Diffractometry ........................................................................................ 37
3.1.1 3.1.2 3.1.3
Introduction to XRD ................................................................................... 38 Grazing Incident X-Ray Diffraction ........................................................... 44 Coupled Scans............................................................................................. 46

Asymmetric Coupled Scans................................................................. 52
Rocking Curves........................................................................................... 54 Pole Figures ................................................................................................ 56
3.1.3.2
3.1.4 3.1.5
3.2 X-Ray Photoelectron Spectroscopy ................................................................... 59 3.3 Secondary Ion Mass Spectrometry..................................................................... 62 3.4 Spectroscopic Ellipsometry................................................................................ 63 3.5 Hall Effect and Transport................................................................................... 68
CHAPTER 4 SCANDIUM NITRIDE GROWTH AND CHARACTERIZATION ........ 72
4.1 Nitrogen Fraction ............................................................................................... 76 4.2 Magnetron Power ............................................................................................... 79 4.3 Substrate Temperature........................................................................................ 81 4.4 Final Optimization.............................................................................................. 84

viii
4.5 ScN Optical and Electronic Properties............................................................... 91
CHAPTER 5 ALUMINUM NITRIDE GROWTH AND CHARACTERIZATION ....... 99
5.1 Nitrogen Fraction ............................................................................................... 99 5.2 Substrate Temperature...................................................................................... 104 5.3 Coil Current...................................................................................................... 108 5.4 Magnetron Power............................................................................................. 112 5.5 Final Optimization............................................................................................ 116 5.6 Piezoelectric Properties.................................................................................... 119
5.6.1 5.6.2
TiN on Al2O3............................................................................................. 119 AlN on TiN on Al2O3................................................................................ 121
CHAPTER 6 TITANIUM OXIDE GROWTH AND CHARACTERIZATION ........... 128 CHAPTER 7 VANADIUM OXIDE GROWTH AND CHARACTERIZATION......... 131
7.1 Deposition of VO2 on Al2O3 ............................................................................ 131 7.2 Deposition of VO2on TiO2 ............................................................................... 134 7.3 VO2 Films by Thermal Oxidation.................................................................... 137
CONCLUSIONS AND FUTURE WORK..................................................................... 151 REFERENCES ............................................................................................................... 152

ix
LIST OF FIGURES
Figure 1.1: Rock-salt crystal structure............................................................................... 3 Figure 1.2: Wurtzite crystal structure ................................................................................ 6 Figure 1.3: Comparison of piezoelectric material maximum use temperatures ................ 7 Figure 1.4: Al1-xScxN piezoelectric coefficients with varying Sc content......................... 8 Figure 1.5: VO2 high temperature rutile phase ................................................................ 10 Figure 1.6: VO2 room temperature monoclinic phase ..................................................... 11 Figure 1.7: TiO2 rutile and anatase structures.................................................................. 13 Figure 2.1: Sputter deposition.......................................................................................... 17 Figure 2.2: Magnetron sputtering field lines.................................................................... 18 Figure 2.3: Simulated electron trajectory in magnetron field.......................................... 19 Figure 2.4: Magnetron plasma at target ........................................................................... 20 Figure 2.5: Magnetron sputter target ............................................................................... 20 Figure 2.6: Denton Vacuum Explorer 14 sputter system................................................. 22 Figure 2.7: Balanced and unbalanced field lines ............................................................. 23 Figure 2.8: Unbalanced magnetron field lines................................................................. 24 Figure 2.9: Simulated electron trajectories in an unbalanced system.............................. 24 Figure 2.10: Plasma in an unbalanced system ................................................................. 25 Figure 2.11: Controllably-unbalanced reactive magnetron sputtering system ................ 26 Figure 2.12: Substrate heating calibration ....................................................................... 27 Figure 2.13: COMSOL 퐵 Simulation.............................................................................. 29 Figure 2.14: Plasma comparison of balanced and unbalanced configuration.................. 30

x
Figure 2.15: Thermal evaporation.................................................................................... 31 Figure 2.16: Electrom beam evaporation......................................................................... 32 Figure 2.17: Ion assisted evaporation .............................................................................. 34 Figure 2.18: Ion assisted evaporation system .................................................................. 35 Figure 3.1: Bragg diffraction ........................................................................................... 39 Figure 3.2: Powder XRD system diagram ....................................................................... 41 Figure 3.3: Powder diffraction scan................................................................................. 42 Figure 3.4: Powder diffraction – differing planes............................................................ 43 Figure 3.5: Example of a GIXRD scan............................................................................ 45 Figure 3.6: Reciprocal space map of Al2O3 ..................................................................... 47 Figure 3.7: Reciprocal space map of Al2O3 – symmetric axis......................................... 48 Figure 3.8: Thin TiN coupled scan .................................................................................. 49 Figure 3.9: Thick TiN coupled scan ................................................................................ 52 Figure 3.10: Reciprocal space map of Al2O3 – asymmetric axis..................................... 53 Figure 3.11: Rocking curve FWHM comparison ............................................................ 55 Figure 3.12: Purely polycrystalline pole figure ............................................................... 57 Figure 3.13: Single crystal pole figure............................................................................. 58 Figure 3.14: CasaXPS peak fitting................................................................................... 60 Figure 3.15: Optical propagation in a film....................................................................... 65 Figure 3.16: Hall Effect configuration............................................................................. 70 Figure 4.1: ScN hexagonal structure................................................................................ 73 Figure 4.2: In plane rotation............................................................................................. 74 Figure 4.3: ScN (111) pole figure.................................................................................... 75

xi
Figure 4.4: Al2O3 (1-12) pole figure................................................................................ 76 Figure 4.5: ScN nitrogen fraction surveys ....................................................................... 78 Figure 4.6: ScN nitrogen fractions – zoomed in.............................................................. 79 Figure 4.7: ScN original power series surveys ................................................................ 80 Figure 4.8: ScN power series – zoomed in ...................................................................... 81 Figure 4.9: ScN temperature series surveys..................................................................... 82 Figure 4.10: ScN temperature series detailed scans......................................................... 83 Figure 4.11: ScN nitrogen fraction at 860°C substrate temperature................................ 84 Figure 4.12: Power series optimization at high temp – original set................................. 85 Figure 4.13: ScN power series optimization at higher temperature................................. 86 Figure 4.14: Surface AFM measurements of ScN power series...................................... 88 Figure 4.15: Rocking curve of 75W ScN sample ............................................................ 89 Figure 4.16: ScN power series rocking curve FWHMs................................................... 90 Figure 4.17: ScN full range optical constants.................................................................. 92 Figure 4.18: ScN bandgap examination of power series ................................................. 93 Figure 4.19: ScN room temperature Hall Effect results .................................................. 94 Figure 4.20: ScN SIMS analysis...................................................................................... 95 Figure 4.21: ScN power series planar spacings ............................................................... 96 Figure 5.1: AlN nitrogen fraction coupled scans........................................................... 101 Figure 5.2: AlN overlaid nitrogen fraction coupled scans............................................. 102 Figure 5.3: AlN fN2 AFM analysis................................................................................. 103 Figure 5.4: AlN substrate temperature stacked coupled scans ...................................... 105 Figure 5.5: AlN overlaid substrate temperature optimization ....................................... 106

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  • Ingénierie Des Défauts Cristallins Pour L'obtention De Gan Semi-Polaire

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    Ingénierie des défauts cristallins pour l’obtention de GaN semi-polaire hétéroépitaxié de haute qualité en vue d’applications optoélectroniques Florian Tendille To cite this version: Florian Tendille. Ingénierie des défauts cristallins pour l’obtention de GaN semi-polaire hétéroépitaxié de haute qualité en vue d’applications optoélectroniques. Autre [cond-mat.other]. Université Nice Sophia Antipolis, 2015. Français. NNT : 2015NICE4094. tel-02947430 HAL Id: tel-02947430 https://tel.archives-ouvertes.fr/tel-02947430 Submitted on 24 Sep 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. UNIVERSITE NICE-SOPHIA ANTIPOLIS - UFR Sciences Ecole Doctorale de Sciences Fondamentales et Appliquées THESE pour obtenir le titre de Docteur en Sciences de l’UNIVERSITE de Nice -Sophia Antipolis Discipline : Physique présentée et soutenue par Florian TENDILLE Ingénierie des défauts cristallins pour l’obtention de GaN semi-polaire hétéroépitaxié de haute qualité en vue d’applications optoélectroniques Thèse dirigée par Philippe VENNÉGUÈS et co-dirigée par Philippe DE MIERRY Soutenue publiquement le : 24-11-2015 Jury : N. Grandjean Professeur, EPFL - LASPE, Lausanne Rapporteur T. Baron Directeur de recherche, CNRS/CEA - LTM, Grenoble Rapporteur E. Monroy Ingénieur chercheur, CEA - INAC, Grenoble Examinateur B.
  • Scandium Nitride Buffer for Gallium Nitride on Silicon Applications

    Scandium Nitride Buffer for Gallium Nitride on Silicon Applications

    84 Technology focus: Nitride materials Scandium nitride buffer for gallium nitride on silicon applications Researchers grow a twin-free single-crystal ScN epitaxial layer as a buffer giving small mismatch for GaN-on-Si. esearchers in Germany are proposing The researchers comment that “based on the use of scandium nitride (ScN) as a suitable buffer for highly insulating oxides, the ScN/Sc2O3/Y2O3/Si buffer Rgallium nitride (GaN) on silicon (Si) growth approach can, in principle, be further engineered for [L. Lupina et al, Appl. Phys. Lett., vol107, p201907, improved electrical breakdown field strength with 2015]. The attraction of ScN is a very small mismatch respect to the Si interface, which is of importance for with GaN of less than 0.1%. This compares with the high-power/high-frequency applications of GaN-on-Si GaN/Si mismatch of ~17%. systems.” However, when ScN is grown directly on silicon the The researchers prepared templates with Sc2O3 and resulting material suffers from serious crystal defects. Y2O3 layers on 4-inch (111) silicon (Sc2O3/Y2O3/Si) by The team — from IHP, Technische Universität Berlin, molecular beam epitaxy. The scandium nitride was Siltronic AG, and BTU Cottbus — has developed a grown on the template in a plasma-assisted molecular growth technique where yttrium (Y2O3) and scandium beam epitaxy (PAMBE) reactor chamber with electron- (Sc2O3) oxide are grown first. These layers allow beam evaporation of elemental scandium and nitrogen single-crystal layers of ScN to be developed that avoid radio-frequency plasma as sources. stacking faults away from the interface. The mismatch X-ray and electron microscope analysis showed that between ScN and Sc2O3 is estimated at 8.5%.
  • Molecular Beam Epitaxy Growth of Scandium Nitride on Hexagonal Sic, Gan, and Aln

    Molecular Beam Epitaxy Growth of Scandium Nitride on Hexagonal Sic, Gan, and Aln

    Molecular Beam Epitaxy Growth of Scandium Nitride on Hexagonal SiC, GaN, and AlN Joseph Casamento1, John Wright1, Reet Chaudhuri2, Huili Grace Xing1,2, and Debdeep Jena1,2 1Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853, USA 2School of Electrical and Computer Engineering, Cornell University, Ithaca, New York 14853, USA RF plasma assisted MBE growth of Scandium Nitride (ScN) thin films on GaN (0001)/SiC, AlN (0001)/Al2O3 and on 6H-SiC (0001) hexagonal substrates is found to lead to a face centered cubic (rock-salt) crystal structure with (111) out-of-plane orientation instead of hexagonal orientation. For the first time, cubic (111) twinned patterns in ScN are observed by in-situ electron diffraction during epitaxy, and the twin domains in ScN are detected by electron backscattered diffraction, and further corroborated with X-ray diffraction. The epitaxial ScN films display very smooth, sub nanometer surface roughness at a growth temperature of 750C. Temperature-dependent Hall-effect measurements indicate a constant high n-type carrier concentration of ~1x1020/cm3 and electron mobilities of ~ 20 cm2/Vs. 1 The III-Nitride semiconductors GaN, InN, and AlN and their heterostructures have triggered a rapid expansion of photonic and electronic device applications into new wavelength, voltage, and frequency regimes. Bringing new and unique physical properties into this semiconductor family by new, epitaxially compatible nitride materials holds the promise to significantly expand what is possible today.[1] The transition metal Sc is stable in a hexagonal crystal structure in its elemental form. The Sc ion, as a group III element, has a stable oxidation state of +3.