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Electrical characterization of ZnO and metal ZnO contacts
Dissertation (MSc)--University of Pretoria, 2010.
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| Format: | Thesis |
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University of Pretoria
2013
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| _version_ | 1867613589519466496 |
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| access_status_str | Open Access |
| author2 | Auret, F.D. (Francois Danie) |
| author_browse | Auret, F.D. (Francois Danie) |
| author_facet | Auret, F.D. (Francois Danie) |
| collection | Thesis |
| dc_rights_str_mv | © 2009, 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, 2010. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/28131 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:38:33.011Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| 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:2263/28131 Electrical characterization of ZnO and metal ZnO contacts Auret, F.D. (Francois Danie) wilbert.mtangi@up.ac.za Nel, J.M. Mtangi, Wilbert Schottky contacts Current transport Barrier height inhomogeneities Barrier height Surface states and claenliness Surface conduction Shallow donors Hall effect Capacitance voltage Current voltage measurements Acceptors Temperature dependent hall measurements Ohmic contacts Fermi level pinning Temperature coefficients UCTD Dissertation (MSc)--University of Pretoria, 2010. The electrical properties of ZnO and contacts to ZnO have been investigated using different techniques. Temperature dependent Hall (TDH) effect measurements have been used to characterize the as-received melt grown ZnO samples in the 20 – 330 K temperature range. The effect of argon annealing on hydrogen peroxide treated ZnO samples has been investigated in the 200 – 800oC temperature range by the TDH effect measurement technique. The experimental data has been analysed by fitting a theoretical model written in Matlab to the data. Donor concentrations and acceptor concentrations together with the associated energy levels have been extracted by fitting the models to the experimentally obtained carrier concentration data by assuming a multi-donor and single charged acceptor in solving the charge balance equation. TDH measurements have revealed the dominance of surface conduction in melt grown ZnO in the 20 – 40 K temperature range. Surface conduction effects have proved to increase with the increase in annealing temperature. Surface donor volume concentrations have been determined in the 200 – 800oC by use of theory developed by D. C. Look. Good rectifying Schottky contacts have been fabricated on ZnO after treating the samples with boiling hydrogen peroxide. Electrical properties of these Schottky contacts have been investigated using current-voltage (IV) and capacitance-voltage (CV) measurements in the 60 – 300 K temperature range. The Schottky contacts have revealed the dominance of predominantly thermionic emission at room temperature and the existence of other current transport mechanisms at temperatures below room temperature. Polarity effects on the Schottky contacts deposited on the O-polar and Zn-polar faces of ZnO have been demonstrated by the IV technique on the Pd and Au Schottky contacts at room temperature. Results obtained indicate a strong dependence of the Schottky contact quality on the polarity of the samples at room temperature. The quality of the Schottky contacts have also indicated their dependence on the type of metal used with the Pd producing contacts with the better quality as compared to the Au. Schottky barrier heights determined using temperature dependent IV measurements have been observed to increase with increasing temperature and this has been explained as an effect of barrier inhomogeneities, while the ones obtained from CV measurements have proved to follow the negative temperature coefficient of the II – VI semiconductor material, i.e. a decrease in barrier height with increasing temperature. However, the values have proved to be larger than the energy gap of ZnO, an effect that has been explained as caused by an inversion layer. Copyright Physics unrestricted 2013-09-07T12:55:50Z 2010-05-26 2013-09-07T12:55:50Z 2010-02-11 2010-05-26 2010-02-11 Dissertation Mtangi, W 2009, Electrical characterization of ZnO and metal ZnO contacts, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/28131 > C10/89/gm http://hdl.handle.net/2263/28131 http://upetd.up.ac.za/thesis/available/etd-02112010-130627/ © 2009, 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 | Schottky contacts Current transport Barrier height inhomogeneities Barrier height Surface states and claenliness Surface conduction Shallow donors Hall effect Capacitance voltage Current voltage measurements Acceptors Temperature dependent hall measurements Ohmic contacts Fermi level pinning Temperature coefficients UCTD Electrical characterization of ZnO and metal ZnO contacts |
| title | Electrical characterization of ZnO and metal ZnO contacts |
| title_full | Electrical characterization of ZnO and metal ZnO contacts |
| title_fullStr | Electrical characterization of ZnO and metal ZnO contacts |
| title_full_unstemmed | Electrical characterization of ZnO and metal ZnO contacts |
| title_short | Electrical characterization of ZnO and metal ZnO contacts |
| title_sort | electrical characterization of zno and metal zno contacts |
| topic | Schottky contacts Current transport Barrier height inhomogeneities Barrier height Surface states and claenliness Surface conduction Shallow donors Hall effect Capacitance voltage Current voltage measurements Acceptors Temperature dependent hall measurements Ohmic contacts Fermi level pinning Temperature coefficients UCTD |
| url | http://hdl.handle.net/2263/28131 http://upetd.up.ac.za/thesis/available/etd-02112010-130627/ |