High Quality Zinc Oxide Thin films and Nanostructures Prepared by Pulsed Laser Deposition for Photodetectors

Handle URI:
http://hdl.handle.net/10754/626351
Title:
High Quality Zinc Oxide Thin films and Nanostructures Prepared by Pulsed Laser Deposition for Photodetectors
Authors:
Flemban, Tahani H. ( 0000-0002-2661-5092 )
Abstract:
Zinc oxide (ZnO) semiconductors have been utilized by many researchers, due to its unique properties beneficial for functional devices. In particular, gadolinium (Gd)–doped ZnO exhibits high ferromagnetic and electrical properties, which is attributed to defect/impurity bands mediated by Gd dopants. In this dissertation, I study the effects of Gd concentration, oxygen pressure using pulsed laser deposition (PLD), and thermal annealing on the optical and structural properties of undoped and Gd-doped ZnO films and nanostructures. Moreover, as the growth of practical ZnO nanostructures-based devices without catalyst, while presently challenging, is highly important for many applications. Thus, for the first time, a novel method is developed for growing well aligned ZnO nanorods (NRs) by optimizing PLD conditions using Gd-doped ZnO target without any catalyst in a single step. This study shows that, both the lattice orientation of the substrate and the Gd characteristics are significant in enhancing the NR growth. Our findings reveal that precise control of the NR density can be achieved by changing the oxygen partial pressure. Furthermore, due to the Gd incorporation, these NRs possess favorable electrical properties with a significant mobility of 177 cm2 (V.s)-1 compared to that reported in literature. Nonetheless significant challenges need to be overcome to achieve reproducible and stable p-type ZnO for commercial applications. Hence, several attempts based on n-type ZnO grown on foreign p-type substrates were made to achieve high-performance devices and overcome the issues arising when p-type doped ZnO is employed. Moreover, Growth of ZnO nanostructures on a foreign p-type substrates does not require a lattice-matched p-type substrate. Thus, for the first time, PLD conditions are improved to grow high quality ZnO nanotubes (NTs) with high optical, structural and electrical properties on a p-type Si (100) substrate without catalyst for high-performance devices. A fabrication of high performance UV photodetector (PD) based on ZnO NT/p-Si is demonstrated with superior responsivity (up to ~ 101.2 AW-1) compared to that reported in literature. This new and simple method demonstrates that the PLD system has a significant potential for improving the performance of materials used in a wide range of electronic and optoelectronic applications.
Advisors:
Roqan, Iman S. ( 0000-0001-7442-4330 )
Committee Member:
Li, Lain-Jong ( 0000-0002-4059-7783 ) ; Rothenberger, Alexander; Al-Dossari, Omar
KAUST Department:
Physical Sciences and Engineering (PSE) Division
Program:
Materials Science and Engineering
Issue Date:
11-Dec-2017
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorRoqan, Iman S.en
dc.contributor.authorFlemban, Tahani H.en
dc.date.accessioned2017-12-11T12:18:28Z-
dc.date.available2017-12-11T12:18:28Z-
dc.date.issued2017-12-11-
dc.identifier.urihttp://hdl.handle.net/10754/626351-
dc.description.abstractZinc oxide (ZnO) semiconductors have been utilized by many researchers, due to its unique properties beneficial for functional devices. In particular, gadolinium (Gd)–doped ZnO exhibits high ferromagnetic and electrical properties, which is attributed to defect/impurity bands mediated by Gd dopants. In this dissertation, I study the effects of Gd concentration, oxygen pressure using pulsed laser deposition (PLD), and thermal annealing on the optical and structural properties of undoped and Gd-doped ZnO films and nanostructures. Moreover, as the growth of practical ZnO nanostructures-based devices without catalyst, while presently challenging, is highly important for many applications. Thus, for the first time, a novel method is developed for growing well aligned ZnO nanorods (NRs) by optimizing PLD conditions using Gd-doped ZnO target without any catalyst in a single step. This study shows that, both the lattice orientation of the substrate and the Gd characteristics are significant in enhancing the NR growth. Our findings reveal that precise control of the NR density can be achieved by changing the oxygen partial pressure. Furthermore, due to the Gd incorporation, these NRs possess favorable electrical properties with a significant mobility of 177 cm2 (V.s)-1 compared to that reported in literature. Nonetheless significant challenges need to be overcome to achieve reproducible and stable p-type ZnO for commercial applications. Hence, several attempts based on n-type ZnO grown on foreign p-type substrates were made to achieve high-performance devices and overcome the issues arising when p-type doped ZnO is employed. Moreover, Growth of ZnO nanostructures on a foreign p-type substrates does not require a lattice-matched p-type substrate. Thus, for the first time, PLD conditions are improved to grow high quality ZnO nanotubes (NTs) with high optical, structural and electrical properties on a p-type Si (100) substrate without catalyst for high-performance devices. A fabrication of high performance UV photodetector (PD) based on ZnO NT/p-Si is demonstrated with superior responsivity (up to ~ 101.2 AW-1) compared to that reported in literature. This new and simple method demonstrates that the PLD system has a significant potential for improving the performance of materials used in a wide range of electronic and optoelectronic applications.en
dc.language.isoenen
dc.subjectZinc oxideen
dc.subjectPulsed laser depositionen
dc.subjectPhotodetectoren
dc.subjectNanotubesen
dc.subjectNanorodsen
dc.subjectOptical propertiesen
dc.titleHigh Quality Zinc Oxide Thin films and Nanostructures Prepared by Pulsed Laser Deposition for Photodetectorsen
dc.typeDissertationen
dc.contributor.departmentPhysical Sciences and Engineering (PSE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen
dc.contributor.committeememberLi, Lain-Jongen
dc.contributor.committeememberRothenberger, Alexanderen
dc.contributor.committeememberAl-Dossari, Omaren
thesis.degree.disciplineMaterials Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id117649en
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