Visible‐NIR Photodetectors Based on Low‐Dimensional GeSe Micro‐Crystals: Designed Morphology and Improved Photoresponsivity

Abstract

GeSe micro‐sheets and micro‐belts have been synthesized by a facile one‐pot wet chemical method in 1‐octadecene solvent and oleic acid solvent, respectively. The adsorption of more oleic acid molecules on the (002) plane promoted growth along [010] direction of the GeSe micro‐belts and limited carrier transport in this direction, resulting in higher carrier concentration and mobility of the GeSe micro‐belts. The performance of the photodetectors based on the single GeSe micro‐sheet and the single GeSe micro‐belt was investigated under illumination at 532 nm, 980 nm and 1319 nm. Both, photodetectors based on a single GeSe micro‐sheet and a single GeSe micro‐belt, exhibit a high photoresponse, short response/recovery times, and long‐term durability. Moreover, the photodetector based on a single GeSe micro‐belt displays a broadband response with a high responsivity (5562 A/W at 532 nm, 1546 A/W at 980 nm) and detectivity (3.01×1012 Jones at 532 nm, 8.38×1011 Jones at 980 nm). These excellent characteristics render single GeSe micro‐belts very interesting for use as highly efficient photodetectors, especially in the NIR region.

Chemical Vapor Deposition of Quaternary 2D BiCuSeO p‐Type Semiconductor with Intrinsic Degeneracy

“…A carrier concentration comparison of BiCuSeO and other typical p‐type 2D semiconductors is shown in Table 1 . [ 44–54 ] The mobility of BiCuSeO is ≈196 cm 2 V −1 s −1 at 2 K. It is noteworthy that the carrier concentration and mobility of 2D BiCuSeO nanosheets sharply change when the temperature is over ≈130 K. A maxima value arising at ≈126 K in the bottom‐right inset in Figure 3c indicates that these phenomena can be assigned to a phase transition of 2D BiCuSeO nanosheets. Although similar behaviors were reported in bulk BiCuSeO, [ 16,17 ] the origin of this phase transition is still ambiguous.…”

Large-Area GeSe Realized Using Pulsed Laser Deposition for Ultralow-Noise and Ultrafast Broadband Phototransistors

“…Even though the D * value gradually decreased with increasing wavelength (beyond 500 nm), the value of RT specific detectivity was more than 5 × 10 9 Jones throughout the IR region probed, which is considerably larger than the noise current-based D * values reported for other 2D IR photodetectors . Here, it is important to note that the significantly high values of D * reported for other solution-processed or mechanically exfoliated GeSe nanoflakes-based photodetectors , are primarily derived from the dark current of the device using the relation: D * prefix= R . A Device 1 / 2 / false( 2 q J d false) 1 / 2 , where q is the electronic charge and J d is the dark current density. This relation is valid only if the shot noise and thermal noise are the major contributor to the total noise of the device, rather than the 1/ f noise .…”

“…3 An ultrafast rise time of 3.2 μs and a fall time of 14.9 μs were recorded for the prepared device, which is much superior to the values reported previously for GeSe-based photodetectors. 31,46,47 Furthermore, the device exhibited fast switching of the incident optical signal up to 150 kHz frequency, but the relative change in photocurrent reduced to 50% of the original value around 60 kHz frequency. Such fast response speed and stable highfrequency operation of the fabricated device reveals the potential capacity of the PLD-grown GeSe to follow highfrequency optical signals.…”

“…Even though the D* value gradually decreased with increasing wavelength (beyond 500 nm), the value of RT specific detectivity was more than 5 × 10 9 Jones throughout the IR region probed, which is considerably larger than the noise current-based D* values reported for other 2D IR photodetectors. 55 Here, it is important to note that the significantly high values of D* reported for other solutionprocessed or mechanically exfoliated GeSe nanoflakes-based photodetectors 20,47 are primarily derived from the dark current of the device using the relation:…”

Enhanced Photoresponse in GeSe‐Based Phototransistors by Ferroelectric Gating

“…[12][13][14] Zhao et al reported a visible-near-infrared (NIR) photodetector based on low-dimensional GeSe microcrystals. [15] Zhao suggested a bottom-gate GeSe-based transistor which can respond to the illumination wavelengths from the visible light to 1400 nm with a fast response speed. [16] Improving the photoresponsivity is one of the most important issues in developing high-performance photodetectors.…”