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Proceedings Paper

Persistent photoconductivity of InP nanowire photoconductors bridged between amorphous silicon electrodes
Author(s): Ataur Sarkar; Logeeswaran V. J.; Nobuhiko P. Kobayashi; Joseph Straznicky; Shih-Yuan Wang; R. Stanley Williams; M. Saif Islam
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Paper Abstract

We fabricated a photo-conducting device with InP nanowires bridged between phosphorous-doped hydrogenated amorphous silicon electrodes. Photoresponse of the device with DC bias was characterized with a white light source and a 630nm He-Ne laser. Experimental results from a large number of devices demonstrate a persistent photoconductivity, a very unique feature of interest. After the light source is shut off, the photogenerated excess carriers recombine very slowly over time and the effect is manifested in the form of persistent photocurrent that takes hours to decay to the dark current level in the range of ~15 nA. Quasi exponential decay of the persistent photocurrent is observed with higher decay rate at the initial stage just after the light source is turned off. Persistent photocurrent magnitude varies with the magnitude of bias voltage, intensity and wavelength of the optical illumination. Experimental decay constant is determined from 0.237/min for -8V bias to 0.174/min for -2V bias. The long recombination time can be attributed to the carrier trapping in the light-induced traps, defects in nanowires and/or in the interface between the nanowires and the amorphous silicon electrodes. Slow recombination process may also originate from the spatial separation of photogenerated electrons and holes by built-in electric fields due to band bending at the heterostructure interfaces between InP nanowire and amorphous silicon electrodes.

Paper Details

Date Published: 10 October 2007
PDF: 7 pages
Proc. SPIE 6768, Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II, 67680P (10 October 2007); doi: 10.1117/12.752679
Show Author Affiliations
Ataur Sarkar, Univ. of California, Davis (United States)
Logeeswaran V. J., Univ. of California, Davis (United States)
Nobuhiko P. Kobayashi, Univ. of California, Santa Cruz (United States)
Joseph Straznicky, Hewlett-Packard Labs. (United States)
Shih-Yuan Wang, Hewlett-Packard Labs. (United States)
R. Stanley Williams, Hewlett-Packard Labs. (United States)
M. Saif Islam, Univ. of California, Davis (United States)

Published in SPIE Proceedings Vol. 6768:
Nanomaterials Synthesis, Interfacing, and Integrating in Devices, Circuits, and Systems II
Nibir K. Dhar; Achyut K. Dutta; M. Saif Islam, Editor(s)

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