Titre : | Study of Schottky diodes based on ultrawide-band gap semiconductors |
Auteurs : | Madani Labed, Auteur ; Seung RimYou, Directeur de thèse ; Noureddine Sengouga, Directeur de thèse |
Type de document : | Monographie imprimée |
Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2022 |
Format : | 1 vol. (161 p.) / couv. ill. en coul / 30 cm |
Langues: | Anglais |
Résumé : |
In this thesis, Ni/β-Ga2O3 Schottky barrier diodes (SBDs) deposited by confined magnetic field based sputtering (CMFS) and Electron-beam evaporation (EBE), are modelled using SILVACO-Atlas and compared to experimental measurements. Firstly, Forward and reverse current of CFMS SBDs were studied. A model was developed to understand the role of Ni atoms diffusion in the surface of β-Ga2O3. In this model, Ni out diffusion combines with oxygen to form a new (NixGa1−x)2O3 interfacial layer. This new compound is modelled as a semiconductor with different energy gap and affinity and less defects since Ni diffusion compensates Ga vacancy related defects. A good agreement between simulation and measurement for forward at high and low temperatures and reverse current with the consideration of band-to-band (BBT) and impact ionization for the reverse current. The achieved agreement demonstrates the soundness of the proposed model. In addition, temperature dependent SBD characteristics were studied. At room temperature, the deviation of SBD parameters from the ideal case is due to the effect of interfacial states due to plasma and Ar bombardment. It was found that the Schottky barrier height ( |
Sommaire : |
Table of Contents Acknowledgement...i Dedication Abstract iv Table of Contents.. v List of figures viii List of tables. xii Introduction1 Chapter 1: β-Ga2O3 material properties..3 1.1. Introduction 3 1.2. Polymorphs and crystal structure of Ga2O3. 3 1.3. Electronic band structure of β-Ga2O3... 7 1.4. Electrical properties .... 8 1.4.1. Free electron concentration, Hall mobility, and resistivity..9 1.4.2. Native deep traps in β-Ga2O3...12 1.5. Optical properties ..... 13 Chapter 2: β-Ga2O3 Schottky barrier diode development and challenges ..16 2.1. Introduction. 16 2.2. Challenge of surface treatment .. 17 2.3. Controlling SBD outputs parameters . 20 2.4. Reverse bias transport mechanisms 24 2.5. Low temperature transport mechanisms and high ideality factor interpretation........... 27 Chapter 3: Ni/β-Ga2O3 Schottky barrier diode fabrication and modeling..28 3.1. Introduction 28 3.2. Schottky barrier diode deposition details 29 3.2.1. Deposition of Si doped β-Ga2O3 drift layer9 3.2.2. Deposition of Ni Schottky contact 31 3.3. The physical models of Ni/β-Ga2O3 Schottky barrier diode 32 3.3.1. Fermi level pinning ..32vi 3.3.2. Image-force lowering34 3.3.3. Carrier recombination models 35 3.3.3.1. Shockley-Read-Hall recombination (SRH).35 3.3.3.2. Auger recombination ..38 3.3.4. Mobility models .38 3.3.4.1. Concentration and temperature dependent mobility ..38 3.3.4.2. Parallel electric field dependent mobility .39 3.3.5. Bandgap models..39 3.3.5.1. Bandgap narrowing .39 3.3.5.2. Bandgap variation with temperature ..40 3.3.6. Impact ionization model ..40 3.3.7. Incomplete ionization...41 3.3.8. Transport models...41 3.3.8.1. Thermionic emission.42 3.3.8.2. Diffusion..42 3.3.8.3. Tunneling...43 3.3.8.4. Band to band tunneling (BBT).43 3.3.9. Self-Heating.44 Chapter 4: Silvaco TCAD simulation .46 4.1. Introduction . 46 4.2. Silvaco overview. 46 4.2.1. Deckbuild .....47 4.2.2. Device generation and simulation using Atlas...48 4.2.2.1. Structure specification..49 4.2.2.2. Materials and models specification53 4.2.2.3. Numerical method selection ..55 4.2.2.4. Solution specification ..56 4.2.2.5. Results analysis .57 Chapter 5: Results and discussion..59 5.1. Introduction 59 5.2. Modelling and optimization of Ni/β-Ga2O3 SBD deposited by CMFS 59vii 5.2.1. Forward bias modelling .60 5.2.1.1. Effect of defective layer thickness..60 5.2.1.2. Effect of band gap and affinity of defected layer...64 5.2.1.3. Effect of Nickel work function.66 5.2.1.4. Effect of the concentration of traps related to plasma and Ar bombardment 66 5.2.1.5. Temperature effect ...68 5.2.1.6. Low temperature modeling.69 5.2.2. Leakage current modelling (reverse bias)....70 5.2.3. Schottky barrier diode parameters modelling..74 5.2.4. Optimizations of Ni/β-Ga2O3 SBD deposited by CMFS...79 5.2.4.1. Undoped layer insertion effect.80 5.2.4.2. TiO2 Edge termination effect.83 5.3. Modelling and optimization Ni/β-Ga2O3 SBD deposited by EBE. 86 5.3.1. Modelling Ni/β-Ga2O3 SBD deposited by EBE 87 5.3.1.1. Effect of Ni workfunction ...87 5.3.1.2. Effect of surface traps88 5.3.1.3. Effect of surface electron affinity 89 5.3.2. Effect of insertion of graphene layer 91 5.3.2.1. Effect of graphene bandgap..93 5.3.2.2. Effect of graphene workfunction..96 5.4. Summary 98 General conclusion.98 Publications and conferences .112 |
En ligne : | http://thesis.univ-biskra.dz/5865/1/Labed%20Madani%20PhD%20thesis-%20Final%20verssion%2015-10-2022.pdf |
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