Recent progress and challenges on two-dimensional material photodetectors from the perspective of advanced characterization technologies

Abstract

Atomically thin two-dimensional (2D) materials exhibit enormous potential in photodetectors because of novel and extraordinary properties, such as passivated surfaces, tunable bandgaps, and high mobility. High-performance photodetectors based on 2D materials have been fabricated for broadband, position, polarization-sensitive detection, and large-area array imaging. However, the current performance of 2D material photodetectors is not outstanding enough, including response speed, detectivity, and so forth. The way to further promote the development of 2D material photodetectors and their corresponding practical applications is still a tremendous challenge. In this article, these issues of 2D material photodetectors are analyzed and expected to be solved by combining micro-nano characterization technologies. The inherent physical properties of 2D materials and photodetectors can be accurately characterized by Raman spectroscopy, transmission electron microscopy (TEM), and scattering scanning near-field optical microscope (s-SNOM). In particular, the precise probe of lattice defects, doping concentration, and near-field light absorption characteristics can promote the researches of low-noise and high-responsivity photodetectors. Scanning photocurrent microscope (SPCM) can show the overall spatial distribution of photocurrent and analyze the mechanism of photocurrent. Photoluminescence (PL) spectroscopy and Kelvin probe force microscope (KPFM) can characterize the material bandgap, work function distribution and interlayer coupling characteristics, making it possible to design high-performance photodetectors through energy band engineering. These advanced characterization techniques cover the entire process from material growth, to device preparation, and to performance analysis, and systematically reveal the development status of 2D material photodetectors. Finally, the prospects and challenges are discussed to promote the application of 2D material photodetectors.

Charge Transfer at the Hetero‐Interface of WSe2/InSe Induces Efficient Doping to Achieve Multi‐Functional Lateral Homo‐Junctions

“…KPFM is greatly powerful to probe the potential distribution of the device, in order to extract the band diagram of the homo-junctions. [40,41] Figure 5a shows the schematics of the KPFM measurements in our work. Both source-drain (V ds ) and gate (V g ) voltages were applied, and then the potential distribution along the channel was measured.…”

Wide-field mid-infrared single-photon upconversion imaging

“…In recent years, tremendous progress has been witnessed in developing sensitive MIR detectors at room temperature 5 , 6 , especially resorting to emerging materials like colloidal quantum dots 7 , black phosphorus 8 , 9 , graphene 10 , and tellurium nanosheet 11 , 12 . To date, the performance of the reported MIR photodetectors is still limited by the high dark current, which results in a noise equivalent power about nW/Hz 1/2 , many orders of magnitude from the single-photon sensitivity 13 . Additional challenge lies in the improvement of the pixel number and the response time, aiming to approach the high-resolution MIR imaging at high-speed frame rates.…”

Highly crystalline hexagonalPbI2sheets on polyaniline/antimony tin oxide surface as a novel and highly efficient photodetector inUV, Vis, and nearIRregions

“…Many materials such as metal oxides, sulfides, and nitrides have been studied for light detection in various light regions. 1,4,5 The performance of photodetectors could be enhanced by increasing the density of active sites on their surface. One efficient route to achieve this goal is through the utilization of materials featuring high surface area.…”