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Photoconductivity of few-layered p-WSe2 phototransistors via multi-terminal measurements

Photoconductivity of few-layered p-WSe2 phototransistors via multi-terminal measurements Recently, two-dimensional materials and in particular transition metal dichalcogenides (TMDs) have been extensively studied because of their strong light–matter interaction and the remarkable optoelectronic response of their field-effect transistors (FETs). Here, we report a photoconductivity study from FETs built from few-layers of p-WSe2 measured in a multi-terminal configuration under illumination by a 532 nm laser source. The photogenerated current was measured as a function of the incident optical power, of the drain-to-source bias and of the gate voltage. We observe a considerably larger photoconductivity when the phototransistors were measured via a four-terminal configuration when compared to a two-terminal one. For an incident laser power of 248 nW, we extract 18 A W−1 and ∼4000% for the two-terminal responsivity (R) and the concomitant external quantum efficiency (EQE) respectively, when a bias voltage Vds = 1 V and a gate voltage Vbg = 10 V are applied to the sample. R and EQE are observed to increase by 370% to ∼85 A W−1 and ∼20 000% respectively, when using a four-terminal configuration. Thus, we conclude that previous reports have severely underestimated the optoelectronic response of transition metal dichalcogenides, which in fact reveals a remarkable potential for photosensing applications. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png 2D Materials IOP Publishing

Photoconductivity of few-layered p-WSe2 phototransistors via multi-terminal measurements

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Copyright
Copyright © 2016 IOP Publishing Ltd
eISSN
2053-1583
DOI
10.1088/2053-1583/3/4/041004
Publisher site
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Abstract

Recently, two-dimensional materials and in particular transition metal dichalcogenides (TMDs) have been extensively studied because of their strong light–matter interaction and the remarkable optoelectronic response of their field-effect transistors (FETs). Here, we report a photoconductivity study from FETs built from few-layers of p-WSe2 measured in a multi-terminal configuration under illumination by a 532 nm laser source. The photogenerated current was measured as a function of the incident optical power, of the drain-to-source bias and of the gate voltage. We observe a considerably larger photoconductivity when the phototransistors were measured via a four-terminal configuration when compared to a two-terminal one. For an incident laser power of 248 nW, we extract 18 A W−1 and ∼4000% for the two-terminal responsivity (R) and the concomitant external quantum efficiency (EQE) respectively, when a bias voltage Vds = 1 V and a gate voltage Vbg = 10 V are applied to the sample. R and EQE are observed to increase by 370% to ∼85 A W−1 and ∼20 000% respectively, when using a four-terminal configuration. Thus, we conclude that previous reports have severely underestimated the optoelectronic response of transition metal dichalcogenides, which in fact reveals a remarkable potential for photosensing applications.

Journal

2D Materials – IOP Publishing

Published: Dec 1, 2016

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