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Title: Enhanced photocurrent response speed in charge-density-wave phase of TiSe 2 -metal junctions
Group IVB transition metal dichalcogenides (TMDCs) have attracted significant attention due to their predicted high charge carrier mobility, large sheet current density, and enhanced thermoelectric power. Here, we investigate the electrical and optoelectronic properties of few-layer titanium diselenide (TiSe 2 )-metal junctions through spatial-, wavelength-, temperature-, power- and temporal-dependent scanning photocurrent measurements. Strong photocurrent responses have been detected at TiSe 2 -metal junctions, which is likely attributed to both photovoltaic and photothermoelectric effects. A fast response time of 31 μs has been achieved, which is two orders of magnitude better than HfSe 2 based devices. More importantly, our experimental results reveal a significant enhancement in the response speed upon cooling to the charge-density-wave (CDW) phase transition temperature ( T CDW = 206 K), which may result from dramatic reduction in carrier scattering that occurs as a result of the switching between the normal and CDW phases of TiSe 2 . Additionally, the photoresponsivity at 145 K is up to an order of magnitude higher than that obtained at room temperature. These fundamental studies not only offer insight for the photocurrent generation mechanisms of group IVB TMDC materials, but also provide a route to engineering future temperature-dependent, two-dimensional, fast electronic and optoelectronic devices.  more » « less
Award ID(s):
1810088 1805924
PAR ID:
10258181
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Nanoscale
ISSN:
2040-3364
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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