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Photoresponse of Natural van der Waals Heterostructures
journal contribution
posted on 2017-05-09, 00:00 authored by Kyle Ray, Alexander E. Yore, Tong Mou, Sauraj Jha, Kirby K. H. Smithe, Bin Wang, Eric Pop, A. K. M. NewazVan
der Waals heterostructures consisting of two-dimensional materials
offer a platform to obtain materials by design and are very attractive
owing to unique electronic states. Research on 2D van der Waals heterostructures
(vdWH) has so far been focused on fabricating individually stacked
atomically thin unary or binary crystals. Such systems include graphene,
hexagonal boron nitride, and members of the transition metal dichalcogenide
family. Here we present our experimental study of the optoelectronic
properties of a naturally occurring vdWH, known as franckeite, which
is a complex layered crystal composed of lead, tin, antimony, iron,
and sulfur. We present here that thin film franckeite (60 nm < d < 100 nm) behaves as a narrow band gap semiconductor
demonstrating a wide-band photoresponse. We have observed the band-edge
transition at ∼1500 nm (∼830 meV) and high external
quantum efficiency (EQE ≈ 3%) at room temperature. Laser-power-resolved
and temperature-resolved photocurrent measurements reveal that the
photocarrier generation and recombination are dominated by continuously
distributed trap states within the band gap. To understand wavelength-resolved
photocurrent, we also calculated the optical absorption properties via density functional theory. Finally, we have shown that
the device has a fast photoresponse with a rise time as fast as ∼1
ms. Our study provides a fundamental understanding of the optoelectronic
behavior in a complex naturally occurring vdWH, and may pave an avenue
toward developing nanoscale optoelectronic devices with tailored properties.
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band gapphotocarrier generationrise timevdWHfranckeiteEQEoptoelectronic propertiesoptoelectronic behaviorwide-band photoresponse2 D van der Waals heterostructuresboron nitridenanoscale optoelectronic devicestrap statestemperature-resolved photocurrent measurementsquantum efficiencyNatural van der Waals Heterostructures Van der Waals heterostructureswavelength-resolved photocurrentcrystalband-edge transitionSuch systemsband gap semiconductortransition metal dichalcogenide familyabsorption properties100 nmroom temperaturematerials offer