A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices
We present a phenomenological model for the photocurrent transient relaxation observed in ZnO-based metal-semiconductor-metal (MSM) planar photodetector devices based on time-resolved surface band bending. Surface band bending decreases during illumination, due to migration of photogenerated holes t...
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| Format: | Article |
| Language: | English |
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MDPI AG
2013-08-01
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| Series: | Sensors |
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| Online Access: | http://www.mdpi.com/1424-8220/13/8/9921 |
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| author | James C. Moore Cody V. Thompson |
| author_facet | James C. Moore Cody V. Thompson |
| author_sort | James C. Moore |
| collection | DOAJ |
| description | We present a phenomenological model for the photocurrent transient relaxation observed in ZnO-based metal-semiconductor-metal (MSM) planar photodetector devices based on time-resolved surface band bending. Surface band bending decreases during illumination, due to migration of photogenerated holes to the surface. Immediately after turning off illumination, conduction-band electrons must overcome a relatively low energy barrier to recombine with photogenerated holes at the surface; however, with increasing time, the adsorption of oxygen at the surface or electron trapping in the depletion region increases band bending, resulting in an increased bulk/surface energy barrier that slows the transport of photogenerated electrons. We present a complex rate equation based on thermionic transition of charge carriers to and from the surface and numerically fit this model to transient photocurrent measurements of several MSM planar ZnO photodetectors at variable temperature. Fitting parameters are found to be consistent with measured values in the literature. An understanding of the mechanism for persistent photoconductivity could lead to mitigation in future device applications. |
| first_indexed | 2024-04-11T12:40:29Z |
| format | Article |
| id | doaj.art-eb6a5d4c65604492a8180523a1032054 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-04-11T12:40:29Z |
| publishDate | 2013-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-eb6a5d4c65604492a8180523a10320542022-12-22T04:23:31ZengMDPI AGSensors1424-82202013-08-011389921994010.3390/s130809921A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector DevicesJames C. MooreCody V. ThompsonWe present a phenomenological model for the photocurrent transient relaxation observed in ZnO-based metal-semiconductor-metal (MSM) planar photodetector devices based on time-resolved surface band bending. Surface band bending decreases during illumination, due to migration of photogenerated holes to the surface. Immediately after turning off illumination, conduction-band electrons must overcome a relatively low energy barrier to recombine with photogenerated holes at the surface; however, with increasing time, the adsorption of oxygen at the surface or electron trapping in the depletion region increases band bending, resulting in an increased bulk/surface energy barrier that slows the transport of photogenerated electrons. We present a complex rate equation based on thermionic transition of charge carriers to and from the surface and numerically fit this model to transient photocurrent measurements of several MSM planar ZnO photodetectors at variable temperature. Fitting parameters are found to be consistent with measured values in the literature. An understanding of the mechanism for persistent photoconductivity could lead to mitigation in future device applications.http://www.mdpi.com/1424-8220/13/8/9921zinc oxideZnOultravioletphotodetectorpersistent photoconductivityphotoresponse |
| spellingShingle | James C. Moore Cody V. Thompson A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices Sensors zinc oxide ZnO ultraviolet photodetector persistent photoconductivity photoresponse |
| title | A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices |
| title_full | A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices |
| title_fullStr | A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices |
| title_full_unstemmed | A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices |
| title_short | A Phenomenological Model for the Photocurrent Transient Relaxation Observed in ZnO-Based Photodetector Devices |
| title_sort | phenomenological model for the photocurrent transient relaxation observed in zno based photodetector devices |
| topic | zinc oxide ZnO ultraviolet photodetector persistent photoconductivity photoresponse |
| url | http://www.mdpi.com/1424-8220/13/8/9921 |
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