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Ultrathin High-Quality SnTe Nanoplates for Fabricating Flexible Near-Infrared Photodetectors
journal contribution
posted on 2020-07-07, 01:15 authored by Junliang Liu, Xiao Li, Han Wang, Guang Yuan, Alexandra Suvorova, Sarah Gain, Yongling Ren, Wen LeiThis work demonstrates
a controlled van der Waals growth of two-dimensional
SnTe nanoplates on mica substrates and their applications in flexible
near-infrared photodetectors. The growth of nonlayered rock-salt structured
SnTe crystals into two-dimensional SnTe nanoplate structures is mainly
caused by the two-dimensional nature of the mica surface, which also
results in the ultrathin nanoplates obtained (3.6 nm, equivalent to
6 monolayers). Furthermore, it is found that the shape of the SnTe
nanoplates can be well engineered by changing their growth temperature
due to the competition between the surface energy of the {100} crystallographic
plane and that of the {111} plane. As a result of the favorable physical
properties of topological crystalline insulators such as metallic
surface (high electron mobility) and narrow bandgap, near-infrared
photodetectors based on single SnTe nanoplate with the thickness of
3.6 nm present excellent device performance with a responsivity of
698 mA/W, a specific detectivity of 3.89 × 108 jones,
and an external quantum efficiency of 88.5% under the illumination
of a 980 nm laser at room temperature (300 K) without applying a gate
voltage (Vg). Upon increasing the gate
voltage from −30 to 30 V, the detector responsivity increases
from 2.96 to 723 mA/W and the detector detectivity increases from
2.4 × 106 to 5.3 × 108 jones. Furthermore,
upon increasing the thickness of SnTe nanoplate from 3.6 to 35 nm,
the detector responsivity increases from 0.698 to 1.468 A/W. The device
performance measured after bending for 300 times as well as after
bending with different radii presents no obvious degradation, which
exhibits the excellent flexibility of the SnTe nanoplate detectors.
These results not only contribute to a deep understanding of the mechanisms
of the van der Waals growth of nonlayered materials into two-dimensional
structure but also demonstrate the immense potential of SnTe nanoplates
to be used in flexible near-infrared detectors.