posted on 2022-03-02, 16:03authored byWeili Zhen, Xi Zhou, Shirui Weng, Wenka Zhu, Changjin Zhang
The
demand for high-performance semiconductors in electronics and
optoelectronics has prompted the expansion of low-dimensional materials
research to ternary compounds. However, photodetectors based on 2D
ternary materials usually suffer from large dark currents and slow
response, which means increased power consumption and reduced performance.
Here we report a systematic study of the optoelectronic properties
of well-characterized rhombohedral ZnIn2S4 (R-ZIS)
nanosheets which exhibit an extremely low dark current (7 pA at 5
V bias). The superior performance represented by a series of parameters
surpasses most 2D counterparts. The ultrahigh specific detectivity
(1.8 × 1014 Jones), comparably short response time
(τrise = 222 μs, τdecay =
158 μs), and compatibility with high-frequency operation (1000
Hz) are particularly prominent. Moreover, a gate-tunable characteristic
is observed, which is attributed to photogating and improves the photoresponse
by 2 orders of magnitude. Gating technique can effectively modulate
the photocurrent-generation mechanism from photoconductive effect
to dominant photogating. The combination of ultrahigh sensitivity,
ultrafast response, and high gate tunability makes the R-ZIS phototransistor
an ideal device for low-energy-consumption and high-frequency optoelectronic
applications, which is further demonstrated by its excellent performance
in optical neural networks and promising potential in optical deep
learning and computing.