DocumentCode :
36258
Title :
Integration of Ni2Si/Si Nanograss Heterojunction on n-MOSFET to Realize High-Sensitivity Phototransistors
Author :
Taghinejad, Mohammad ; Taghinejad, Hossein ; Ganji, M. ; Rostamian, A. ; Mohajerzadeh, Shamsoddin ; Abdolahad, Mohammad ; Kolahdouz, M.
Author_Institution :
Sch. of Electr. & Comput. Eng., Univ. of Tehran, Tehran, Iran
Volume :
61
Issue :
9
fYear :
2014
fDate :
Sept. 2014
Firstpage :
3239
Lastpage :
3244
Abstract :
We report a top-down fabrication technique for direct integration of Ni2Si/Si heterojunction arrays on n-type MOSFET gate terminal to realize sensitive field-effect phototransistors (PTs). It was observed that exposing gate area to light (λ = 655 nm) leads to significant modulation of threshold voltage (VTH) of PT in comparison with a conventional MOSFET. By analyzing optical absorption spectra of Ni2Si/Si nanostructures on SiO2 of this novel PT and planar Ni2Si/poly-Si on SiO2 of conventional transistors, we concluded that, nanostructures strongly improve light absorption. This results in higher optically generated electron-hole pairs in which excess holes induce an electric field on the transistor channel and help the threshold happen at lower voltages. To recognize the appropriate operating point of such nanostructure-based PT, effect of VGS on the sensitivity of drain current was investigated. Experimental results show that device sensitivity (S) is related to gate-source voltage via a homographic like function. Theoretical analysis shows S ∝ 1/(VGS - VTH) for high VGS, which has been confirmed by experimental data. In addition, external quantum efficiency and photoresponsivity of PT as functions of gate voltage were studied. The achieved results suggest that this device would be a promising candidate for fabricating low-power PTs based on silicide nanostructures.
Keywords :
MOSFET; elemental semiconductors; light absorption; low-power electronics; nanostructured materials; nickel compounds; phototransistors; semiconductor device testing; silicon; spectra; Ni2Si-Si heterojunction arrays; Ni2Si-Si; SiO2; device sensitivity; drain current; external quantum efficiency; gate-source voltage; homographic like function; light absorption; low-power PT; n-type MOSFET gate terminal; nanostructure-based PT; optical absorption spectra; optically generated electron-hole pairs; photoresponsivity; sensitive field-effect phototransistors; silicide nanostructures; threshold voltage; top-down fabrication technique; transistor channel; wavelength 655 nm; Heterojunctions; Logic gates; Nanostructures; Nickel; Optical device fabrication; Sensitivity; Silicon; Electro-optical properties; nickel silicide; optical absorption; phototransistor (PT); silicon nanograss;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/TED.2014.2341614
Filename :
6880441
Link To Document :
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