PolyU IR
 

PolyU Institutional Repository >
Applied Physics >
AP Theses >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/3373

Title: Semiconducting properties of oxide thin films prepared by pulsed laser deposition
Authors: Lam, Ching-yee
Subjects: Thin films
Pulsed laser deposition
Hong Kong Polytechnic University -- Dissertations
Issue Date: 2005
Publisher: The Hong Kong Polytechnic University
Abstract: All oxide p-n junctions have been successfully grown by pulsed laser deposition method. Three different p-n junctions, namely LaxSrxMnO₃/SrTiO₃/La1-ySryTiO₃, La₀.₇Sr0.₃MnO₃/Nb-1wt% doped SrTiO₃ and Li₀.₁₅Ni₀.₈₅O/La₀.₀₅Sr₀.₉₅TiO₃ have been fabricated. Structural characterization by x-ray diffraction reveals excellent heteroepitaxial relation in all these junctions. The diffusion potential of La1-xSrxMnO₃/SrTiO₃/La1-ySryTiO₃, La₀.₇Sr₀.₃MnO₃/Nb-lwt% doped SrTiO₃ and Li₀.₁₅Ni₀.₈₅O/La₀.₀₅Sr₀.₉₅TiO₃ junctions are 1eV, 0.2eV, and 0.3eV respectively. All of the fabricated p-n junctions yield typical I-V characteristics and display good rectifying property under room temperature. According to the high thermal stability property of oxides, all-oxide p-n junction could operate at temperature up to 500K. Throughout the research, it is observed that even a highly conducting and metallic-like oxide film could form good p-n junction. However the narrow depletion layer causes a large leakage current under the reverse biased condition. The insertion of insulating layer (SrTiO₃) helps in "broadening" the depletion layer and hence prevents the occurrence of large leakage current. Unfortunately the turn-on voltage increases as well. So a compromise between the reduction of leakage current and the increases of turn-on voltage should be made. It is consideration that ultimately determines the optimum insulating layer thickness. The high temperature operation (~500K) has been confirmed in all junctions. In general, the change in leakage current and turn-on voltage of all-oxide p-n junctions follow the same pattern as those seen in conventional semi-conductor counterparts. La₀.₇Sr₀.₃MnO₃ is a well known magnetoresistance material. It exhibits a large positively MR. We have studied influence of the magnetic field on the La₀.₇Sr0₃MnO₃/Nb-lwt% doped SrTiO₃ junction transport properties at room temperature. The La₀.₇Sr0.₀.₃MnO₃ film, which is grown at 100mTorr, has the phase transition at 290K. It has been shown that the junction works stably upon a 1T magnetic field application. No apparent spin dependent junction transport properties have been observed. Photo-response has been investigated for the all-transparent oxide Li₀.₁₅Ni₀.₈₅O/La₀.₀₅Sr₀.₉₅TiO₃ junction as well. This junction potentially can act as a UV photo-detector. The highest photo-response occurs at 340nm. The junction provides a photovoltage of 377mV under 1.28mW UV illumination.
Degree: M.Phil., Dept. of Applied Physics, The Hong Kong Polytechnic University, 2005
Description: viii, 164 leaves : ill. ; 30 cm.
PolyU Library Call No.: [THS] LG51 .H577M AP 2005 Lam
Rights: All rights reserved.
Type: Thesis
URI: http://hdl.handle.net/10397/3373
Appears in Collections:AP Theses
PolyU Electronic Theses

Files in This Item:

File Description SizeFormat
b1793803x_ir.pdfFor All Users (Non-printable) 4.35 MBAdobe PDFView/Open
b1793803x_link.htmFor PolyU Users 162 BHTMLView/Open



Facebook Facebook del.icio.us del.icio.us LinkedIn LinkedIn


All items in the PolyU Institutional Repository are protected by copyright, with all rights reserved, unless otherwise indicated.
No item in the PolyU IR may be reproduced for commercial or resale purposes.

 

© Pao Yue-kong Library, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
Powered by DSpace (Version 1.5.2)  © MIT and HP
Feedback | Privacy Policy Statement | Copyright & Restrictions - Feedback