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Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode
Dissertation (MSc)--University of Pretoria, 2015.
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| Format: | Thesis |
| Language: | English |
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University of Pretoria
2015
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| _version_ | 1867613496637652992 |
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| access_status_str | Open Access |
| author2 | Meyer, W.E. (Walter Ernst) |
| author_browse | Meyer, W.E. (Walter Ernst) |
| author_facet | Meyer, W.E. (Walter Ernst) |
| collection | Thesis |
| dc_rights_str_mv | © 2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2015. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/49880 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:37:04.556Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/49880 Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode Meyer, W.E. (Walter Ernst) Auret, F.D. (Francois Danie) Van Schalkwyk, Louwrens Aluminium gallium nitride Iridium(IV) oxide Optoelectronic Ultraviolet (UV) UV-to-visible rejection ratio UCTD Dissertation (MSc)--University of Pretoria, 2015. Several applications require the detection of terrestrial UV-C signatures. Efficiency, compactness, environmentally friendly and cost-effective requirements for UV-C–detectors resulted in a research interest in wide-bandgap (WBG) semiconductor-based photovoltaic diodes with a 280 nm cut-off wavelength. Advances in producing group-III-nitride materials allowed the growth of high quality Al[x]Ga[1−x]N, a direct-WBG ternary semiconductor in which the Al mole fraction (x) could be varied, allowing for a tuneable bandgap that made the semiconductor intrinsically 'blind' to longer wavelengths and responsive to selected wavelengths shorter than 360 nm. This dissertation reports on the development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode. A fabrication procedure was established using optimized metallization techniques derived from literature. This included metallization schemes, metal thicknesses and annealing methods for metallization of both the ohmic and Schottky contacts for a front-irradiated photodiode. Characterization was done with a newly constructed optoelectronic characterization system. Electrical characterization was performed inside a light-tight shielded enclosure and a software routine aided in applying current–voltage and capacitance–voltage measurements on a Schottky diode. Spectral characterization made use of either a UV source or a visible-to-near-infrared source that was coupled to a monochromator that allowed for wavelength selection. The monochromatic electromagnetic radiation was guided by an optical fibre from the monochromator into the enclosure where the photodiode was irradiated. An additional software routine was developed that allowed for the automation of the spectral characterization. The system was calibrated against standards traceable to the National Institute of Standards and Technology (NIST) by following the photodetector substitution method. The study concluded with the manufacturing of an epoxy wire-bonded front-irradiated four-quadrant detector that was mounted on a commercial microchip carrier. Metal depositions were done through physical contact masks. The quadrants were surrounded with optimized layered ohmic contacts and a quadrant consisted of a thin-film iridium(IV) oxide (IrO₂) as Schottky contact that is UV transmissive with a Au contact on top to which a wire was bonded. Optoelectronic characterization verified that the four-quadrant detector was intrinsically solar-blind and showed good uniformity across the quadrants. Electrical parameters obtained included an average ideality factor of 1.97 ± 0.09, a Schottky barrier height of (1.22 ± 0.08) eV, a reverse leakage current density of (2.1 ± 3.3) nA/cm² and a series resistance of (120 ± 30) Ω. Spectral parameters obtained included a (275 ± 5) nm cut-off wavelength, an average current responsivity at 250 nm of (28 ± 1.0) mA/W with a quantum efficiency of (14 ± 0.5) % and an UV-to-visible and near-infrared rejection ratio between 10³ and 10⁵ for 400 nm to 1100 nm wavelengths. These characteristics allowed for the detector to be used in demonstrating a working solar-blind UV-sensitive electro-optic device. Physics Unrestricted 2015-09-15T09:25:24Z 2015-09-15T09:25:24Z 2016-04 2015 Dissertation van Schalkwyk, L 2015, Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/49880> A2016 http://hdl.handle.net/2263/49880 en © 2016 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Aluminium gallium nitride Iridium(IV) oxide Optoelectronic Ultraviolet (UV) UV-to-visible rejection ratio UCTD Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title | Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title_full | Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title_fullStr | Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title_full_unstemmed | Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title_short | Development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode |
| title_sort | development and characterization of a tuneable algan based solar blind uv sensitive schottky photodiode |
| topic | Aluminium gallium nitride Iridium(IV) oxide Optoelectronic Ultraviolet (UV) UV-to-visible rejection ratio UCTD |
| url | http://hdl.handle.net/2263/49880 |