High-performance Schottky photodiodes with asymmetric metal contacts based on 2D Bi2O2Se
Presentation of results
Two-dimensional Bi2O2Se is a newly developed 2D semiconductor material with air stability, medium band gap width (0.8 eV) and high carrier mobility, showing great promise in optoelectronics. However, due to the high carrier mobility and conductivity, the 2D Bi2O2Se-based photodetectors have been reported to have the disadvantage of high dark currents.
In view of this, professor Huang Kai's team at Xiangtan University recently used asymmetric electrode technology to build a Schottky photodiode based on 2D Bi2O2Se. Due to the Schottky barrier, the device's dark current is significantly suppressed, and the photodetector avoids the complex and sophisticated preparation of traditional heterojunction devices. The photodetector shows a broadband response in the range of 450 to 1400 nm (visible-NIR), with response and detection rates of 1.2 A W-1 and 7×1011 Jones under 500 nm light (6.4 mW cm-2), respectively. In addition, the device achieves fast response at more than three orders of magnitude of on/off ratios and zero bias (rise time 117 ms, fall time 58.5 ms). What's more, at the external bias (-0.5 V), the response rate reaches 193 A W-1, and the outer quantum efficiency exceeds 47899%. These results show the unlimited potential of 2D Bi2O2Se in high-sensitivity, wideband and low-power optoelectronic devices.
Illustrated reading
Figure 1. Characterization of 2D Bi2O2Se nanosheets grown on a fluorlogene mica substrate.
Figure 2. (a) Schematic diagram of the Pd/Bi2O2Se/Ti photodetector under irradiation. (b) OM image of the device. (c) The work function of Pd and Ti and the band plot of Bi2O2Se. (d) Logarithmic I-V curve of Pd/Bi2O2Se/Ti photodiode. (e) Band diagram of the device at different Vds.
Figure 3. (a) Band diagram of the device at zero bias under irradiation. (b) Correspondence between the current of light and the wavelength of incident light. (c&d) Time response of photodetectors at visible and infrared wavelengths. (e) Photocurrent imaging of Pd/Bi2O2Se/Ti photodetectors at zero bias.
Figure 4. (a) I-V curves of the device at different laser power densities (500 nm). (b) The correspondence between the on/off ratio and the laser power density at zero bias. (c) The relationship between photocurrent and laser power density. (d) Dependence of response rate and detection rate on laser power density. (e) The rise and fall curves of the device under 500 nm light exposure. (f) Response curve of the device 100 optical on/off cycles at zero bias.
Figure 5. (a&b) A single period of the I-T curve under positive and negative bias. (c&d) band plot of the device in positive and negative bias light. (e) Photocurrent and response rate at different bias voltages. (f) EQE at different bias voltages.
Literature information
A High-Performance Schottky Photodiode with Asymmetric Metal Contacts Constructed on 2D Bi2O2Se
(Adv. Electron. Mater., 2022, DOI:10.1002/aelm.202100987)
Literature Links: Links to web pages
