| Titre : | Study of gallium-oxide-base dultravioletphoto-detectors |
| Auteurs : | RIMA CHERROUN, Auteur ; Afak Meftah., Directeur de thèse |
| Type de document : | Thése doctorat |
| Editeur : | Biskra [Algérie] : Faculté des Sciences Exactes et des Sciences de la Nature et de la Vie, Université Mohamed Khider, 2024 |
| Format : | 1VOL.(125p) / ill.couv.ill.en coul / 30cm |
| Langues: | Anglais |
| Langues originales: | Anglais |
| Mots-clés: | IZTO/β-Ga2O3, SB UV-PhD, numerical simulation, traps, the persistent photoconductivityphenomenon,passivationlayer(Al0.39Ga0.61)2O3,bufferlayer,4H-SiCsuB strate,Graphene,Schottkycontact,highoperatingtemperature |
| Résumé : |
This study presents a numerical simulation of an IZTO/β-Ga2O3 Schottky barrier ultravioletphotodetector(SBUV-PhD),commonlyreferredtoasasolar-blindUVphotodetector, designedtooperatespecificallyatawavelengthof255nm. Thesimulationswereperformed using SILVACO-ATLAS, a renowned 2D and 3D modeling software. Key parameters investigated include the current density–voltage (J–V) characteristics, responsivity, and internal quantumefficiency(IQE),withanadditionalfocusondetectivityandtime-dependentphoto response (T-D PhR). The study is organized into two main parts. Initially, efforts were directedtowardsreplicatingexperimentalJ–Vcharacteristicsundervariousconditions: inthe dark and illuminated with wavelengths of 500nm, 385nm, and 255nm. Notably, the influence of shallow and deep traps, particularly on persistent photoconductivity (PPC), was examined. The most significant impact was observed from the deepest traps (ET =0.74eV andET =1.04eV), whichcontributedtoadecaytimeof0.05s. Moreover, incorporatingan (Al0.39Ga0.61)2O3 passivation layer on the device’s surface significantly enhanced its performance. Inthesecondpartofthestudy,furtheroptimizationwaspursuedbysubstitutingthe β-Ga2O3:Sn substrate with 4H-SiC and introducing a buffer layer between theβ-Ga2O3:Si drift layer and the new substrate. Additionally, the top contact IZTO was replaced with Graphene, considering the effect of work function and electronic affinity. These optimizationsyieldedenhanceddevicemetrics: aphotocurrentdensityof7.38×10−5A/cm2,responsivityof0.074A/W, IQEof0.57, anddetectivityof5×1012Jones at-1V under255nm illumination. Furthermore,thedevicedemonstratedrobustnessatelevatedoperatingtemperatures. Insummary,thisresearchnotonlysimulatedtheperformanceoftheIZTO/β-Ga2O3 SBUV-PhDunderspecificoperatingconditionsbutalsoexploredsignificantenhancements throughmaterialandstructuraloptimizations,therebyimprovingitsoverallphotodetection capabilities. |
| Sommaire : |
1Introduction 2 1 AnoverviewofGa2O3properties 6 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2 HistoryofGa2O3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.2.1 Discoveryandearlystudies(1960s-1990s) . . . . . . . . . . . . . . . . . . 6 1.2.2 EmergenceofGa2O3 (1990s-2010s) . . . . . . . . . . . . . . . . . . . . . . 7 1.2.3 Commercialandindustrialinterest(2010s-present) . . . . . . . . . . . . 7 1.3 FundamentalpropertiesofGa2O3 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.1 Structuralproperties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2 Electricalproperties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3.2.1 Electronicstructure . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.3.2.2 Controllingconductivityanddoping . . . . . . . . . . . . . . . . . 11 1.3.3 Opticalproperties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.3.4 Thermalproperties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.4 OverviewofGa2O3 defects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.4.1 NativedefectsinGa2O3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.4.1.1 Oxygenvacancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.4.1.2 Galliumvacancies . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4.1.3 Nativedeeptraps . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4.2 ExtrinsicdefectsinGa2O3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 1.4.2.1 Shallowdonors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 .4.2.2 Deepacceptors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1.5 GrowthmechanismsinGa2O3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 1.6 ThemostimportantapplicationsofGa2O3 . . . . . . . . . . . . . . . . . . . . . . 20 2 Solar-blindUVphotodetectorsbasedonGa2O3 23 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.2 ClassificationofUVphotodetectorsanditsworkingprinciple . . . . . . . . . . . 24 2.2.1 Photodetectorsbasedonexternalphotoelectricphenomenon . . . . . . 24 2.2.1.1 Photoemissivedetector(vacuumUVdetector) . . . . . . . . . . . 24 2.2.2 Photodetectorsbasedoninternalphotoelectricphenomenon . . . . . . . 25 2.2.2.1 SolidstateUVdetectors(semiconductorsbasedphotodetectors) 25 2.3 PrimaryparametersofUVphotodetectors . . . . . . . . . . . . . . . . . . . . . . 29 2.4 DevelopmentofUVdetectormaterials . . . . . . . . . . . . . . . . . . . . . . . . 32 2.4.1 Ga2O3 solar-blindUVphotodetectors . . . . . . . . . . . . . . . . . . . . . 32 2.4.2 ComparisonofUVdetectorsandtheirparametersbasedonGa2O3 with differentconfigurations(Themostrecentresearch) . . . . . . . . . . . . . 36 2.4.3 ConstraintsoftheGa2O3 UVphotodetectors . . . . . . . . . . . . . . . . . 39 2.4.4 EnhancingtheperformanceoftheGa2O3UVphotodetectorsbyapplying a(AlxGa1–x)2O3 passivationlayer . . . . . . . . . . . . . . . . . . . . . . . . 40 2.4.5 Theoptimalsubstrates(semi-insulators)forthedepositionoftheGa2O3 UVphotodetectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 2.4.6 EnhancingtheperformanceoftheGa2O3 UVphotodetectorsbyadd-ing abufferlayerbetweentheGa2O3 epitaxiallayerandsubstrate . . . . . . . 43 2.4.7 Enhancing the performance of the Ga2O3 UV photodetectors by using GrapheneasSchottkycontact . . . . . . . . . . . . . . . . . . . . . . . . . . 44 2.4.8 TheimpactofhighoperatingtemperatureontheGa2O3UVphotodetectorsperf44 3 BasicsofSchottkydevicesimulationbySILVACO-ATLAS 47 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 3.2 ThefunctionalphysicalmechanismsinSchottkycontact . . . . . . . . . . . . . . 47 3.2.1 Fermi-levelpinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 3.2.2 Image-forcelowering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.2.3 Carrierrecombination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.2.3.1 SRHrecombination . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 3.2.3.2 Augerrecombination . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.2.4 Thermionicemission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 3.2.5 Diffusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.2.6 Tunneling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.2.6.1 Bandtobandtunneling . . . . . . . . . . . . . . . . . . . . . . . . . 54 3.3 SimulationbySILVACO-ATLASsoftware . . . . . . . . . . . . . . . . . . . . . . . 55 3.3.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 3.3.2 Deckbuild . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 3.3.2.1 Structurespecification . . . . . . . . . . . . . . . . . . . . . . . . . 58 3.3.2.2 Materialsandmodelsspecification . . . . . . . . . . . . . . . . . . 61 3.3.2.3 Numericalmethodselection . . . . . . . . . . . . . . . . . . . . . . 66 3.3.2.4 Solutionspecification . . . . . . . . . . . . . . . . . . . . . . . . . . 66 3.3.2.5 Resultsanalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 4 Resultsanddiscussion 70 4.1 Introduction . . . . . . . . . . . . . . . . . . . . 4.2 Devicestructureandmodelling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 4.3 Reversebiasmodeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 4.4 Optimizationsofβ-Ga2O3 SBUV-PhD . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.4.1 Effectofreducingbulktrapsdensity . . . . . . . . . . . . . . . . . . . . . . 75 4.4.1.1 J-Vcharacteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 4.4.1.2 Theresponsivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 4.4.1.3 Photocurrentdensityversuslightpowerdensity . . . . . . . . . . 77 4.4.1.4 Timedependencyphoto-response . . . . . . . . . . . . . . . . . . 78 4.4.2 Effectofinsertingan(Al0.39Ga0.61)2O3 passivationlayer . . . . . . . . . . 79 4.4.2.1 J–Vcharacteristic . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 4.4.2.2 Thegenerationandrecombinationrates . . . . . . . . . . . . . . 80 4.4.2.3 Internalquantumefficiency . . . . . . . . . . . . . . . . . . . . . . 81 4.4.2.4 Time-dependencyphoto-response . . . . . . . . . . . . . . . . . . 81 4.4.3 Effectofsubstitutingβ-Ga2O3:Snsubstratewith4H-SiCsubstrate. . . . . 82 4.4.3.1 Effectoftrapsin4H-SiCsubstrate. . . . . . . . . . . . . . . . . . . 88 4.4.4 Effectofincorporatingabufferlayerbetweenβ-Ga2O3:Sidriftlayerand 4H-SiCsubstrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 4.4.4.1 Effectofelectronicaffinityofthebufferlayer . . . . . . . . . . . . 94 4.4.5 EffectofsubstitutingIZTOwithGraphene . . . . . . . . . . . . . . . . . . 95 4.4.5.1 EffectofGrapheneworkfunction . . . . . . . . . . . . . . . . . . . 98 4.4.6 Effectofhighoperatingtemperature . . . . . . . . . . . . . . . . . . . . . . 99 4.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Conclusion 104 Bibliography 107 Publications and conferences 130 |
| Type de document : | Thése doctorat |
| En ligne : | http://thesis.univ-biskra.dz/id/eprint/6821 |
Disponibilité (1)
| Cote | Support | Localisation | Statut |
|---|---|---|---|
| TPHY/148 | Théses de doctorat | bibliothèque sciences exactes | Consultable |
