| EPSRC Reference: |
GR/J17111/01 |
| Title: |
VISIBLE LIGHT EMITTING DEVICES USING POROUS SILICON |
| Principal Investigator: |
ODonnell, Professor K |
| Other Investigators: |
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| Researcher Co-Investigators: |
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| Project Partners: |
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| Department: |
Physics |
| Organisation: |
University of Strathclyde |
| Scheme: |
Standard Research (Pre-FEC) |
| Starts: |
28 April 1993 |
Ends: |
27 October 1995 |
Value (£): |
157,227
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| EPSRC Research Topic Classifications: |
| Optoelect. Devices & Circuits |
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Summary on Grant Application Form |
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a) Fabrication of Electroluminescent and Cathodoluminescent devices using porous silicon and the active medium.b) Experimental investigation and theoretical modelling of luminescence mechanisms of porous silicon.c) Fabrications of quantum dot arrays in silicon by dry-etching and ion-beam ablation techniques with a view to generating luminescence from the processed material.Progress:a) A process has been developed using Silicon Nitride (deposited by Microelectronics Centre, Southampton University) as a Hydrofluoric Acid resistant mask for the fabrication of isolated, discrete areas of Porous Silicon. Hence discrete Porous Silicon devices with diode I-V characteristics have been fabricated. However electoluminescence and cathodoluminescence have not been observed and work continues.b) The effect of wetting (primarily by aqueous Hydrofluoric Acid and Potassium Hydroxide) in the photoluminescence of Porous Silicon has been experimentally investigated. The dramatic effects of these chemical agents on the photoluminescence indicate the importance of surface chemistry in Porous Silicon photoluminescence. These experimental results have been interpreted in terms of a model of the state of surface termination of the Porous Silicon.c) Arrays of Silicon columns have been fabricated by RAL. These will be further processed using oxidation and wet etching steps increase quantum confinement effects. These structures will be investigated for luminescent behaviour.d) Post processing of conventionally prepared material using Potassium Hydroxide has been used produce Porous Silicon with broadband photoluminescence which appears white to the naked eye. As a result of the post processing a blue photoluminescence band is observed in addition to the conventional red/orange band.e) The temperature dependence an temporal behaviour of Porous Silicon photoluminescence has also been investigated experimentally and described theoretically in terms of carrier-hopping-assisted recombination within a fluctuating width quantum wire. It has been found that the room temperature blue photoluminescence decays after the excitation pulse on a single time scale of 123 ns, in contrast the time scale for between 550 and 750nm increases from 0.3 to 3.7-s. In addition the intensity of the time delayed orange luminescence (500 ns after excitation) increases but the intensity of luminescence coincident with the excitation pulse decreases with increasing temperature. These results are consistent with thermally assisted trapping/detrapping of uncombined carriers in a disordered potential followed by radiative recombination.
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Key Findings |
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Potential use in non-academic contexts |
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Impacts |
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| Description |
This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk |
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| Date Materialised |
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Sectors submitted by the Researcher |
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This information can now be found on Gateway to Research (GtR) http://gtr.rcuk.ac.uk
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| Project URL: |
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| Further Information: |
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| Organisation Website: |
http://www.strath.ac.uk |