Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation
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2019
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu15554957329361012021-08-03T07:10:29Z Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation Farzana, Esmat Electrical Engineering Ga2O3 Defects Schottky barrier Deep levels DLTS DLOS Radiation Neutron Crystal Orientation Beta-phase gallium oxide (β-Ga2O3) is attracting significant interest for high-power electronics and ultraviolet optoelectronics due to its ~4.8 eV wide bandgap, large predicted breakdown field, ability to support β-(Al1-xGax)2O3/Ga2O3 heterojunctions, and the availability of large area, melt-grown native substrates for homoepitaxial growth. There is also continued interest for space-based applications due to its predicted high radiation hardness compared to contemporary wide bandgap materials (III-nitrides and SiC). However, the integration of β-Ga2O3 into prospective applications will largely depend on device design innovations as well as the availability of high quality and low defect-density materials. This is considerably important as crystalline defects can adversely affect material properties critical to device operation, output power, threshold voltage, and carrier mobility by causing carrier compensation, scattering, and trapping effects. Defect-induced degradation can also dictate the entire behavior of β-Ga2O3 devices in their intended space-based applications where exposure to energetic radiation particles is typical, leading to introducing defect states in the bandgap. Furthermore, there is an intense need of understanding of metal/ β-Ga2O3 contact and interface properties to ensure large Schottky barrier height and low leakage current for high power operations. However, despite remarkable early progress, the underlying knowledge of metal contact properties, dopants, electrically active defects, and their role on material properties is still very limited. Hence, this research aims to pursue a comprehensive investigation of defects in β-Ga2O3 bandgap, building from the native β-Ga2O3 substrate to subsequent homoepitaxial layers. Using deep level transient and optical spectroscopy (DLTS/DLOS) techniques, experiments have been undertaken to understand the formation, physical structure, electronic, and optical properties of defects in β-Ga2O3 bandgap, with correlation to theoretical studies. Specifically, by exploring melt-grown unintentionally doped (Si background dominated) substrate and Ge-doped plasma-assisted molecular beam epitaxy (PAMBE)-grown epitaxy, the impact of dopant choice and growth method on formation of deep levels in β-Ga2O3 has been investigated. In addition, the electronic properties and behaviors of deep levels in the β-Ga2O3 substrate and epitaxy material under high energy neutron exposure have been investigated, with a goal to understand the degradation mechanisms induced by the irradiation-induced defects. Such findings will also greatly assist the elucidation of the physical sources of deep levels since intrinsic defects are susceptible to respond to irradiation, and aid in optimizing growth conditions for enabling radiation-hardened β-Ga2O3 devices. Moreover, metal/β-Ga2O3 Schottky contact and interface characteristics have been investigated to analyze Schottky barrier heights, transport mechanisms, and correlation of work function and barrier height with different metal choices which can provide a pathway of gate metal engineering for high performance devices. 2019-09-04 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1555495732936101 http://rave.ohiolink.edu/etdc/view?acc_num=osu1555495732936101 unrestricted This thesis or dissertation is protected by copyright: some rights reserved. It is licensed for use under a Creative Commons license. Specific terms and permissions are available from this document's record in the OhioLINK ETD Center. |
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NDLTD |
| language |
English |
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NDLTD |
| topic |
Electrical Engineering Ga2O3 Defects Schottky barrier Deep levels DLTS DLOS Radiation Neutron Crystal Orientation |
| spellingShingle |
Electrical Engineering Ga2O3 Defects Schottky barrier Deep levels DLTS DLOS Radiation Neutron Crystal Orientation Farzana, Esmat Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| author |
Farzana, Esmat |
| author_facet |
Farzana, Esmat |
| author_sort |
Farzana, Esmat |
| title |
Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| title_short |
Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| title_full |
Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| title_fullStr |
Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| title_full_unstemmed |
Defects and Schottky Contacts in β-Ga2O3:Properties, Influence of Growth Method and Irradiation |
| title_sort |
defects and schottky contacts in β-ga2o3:properties, influence of growth method and irradiation |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2019 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1555495732936101 |
| work_keys_str_mv |
AT farzanaesmat defectsandschottkycontactsinbga2o3propertiesinfluenceofgrowthmethodandirradiation |
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1719455471448883200 |