Abstract
A photodetector converts optical signals to detectable electrical signals. Lately, self-powered photodetectors have been widely studied because of their advantages in device miniaturization and low power consumption, which make them preferable in various applications, especially those related to green technology and flexible electronics. Since self-powered photodetectors do not have an external power supply at zero bias, it is important to ensure that the built-in potential in the device produces a sufficiently thick depletion region that efficiently sweeps the carriers across the junction, resulting in detectable electrical signals even at very low-optical power signals. Therefore, two-dimensional (2D) materials are explored as an alternative to silicon-based active regions in the photodetector. In addition, plasmonic effects coupled with self-powered photodetectors will further enhance light absorption and scattering, which contribute to the improvement of the device’s photocurrent generation. Hence, this review focuses on the employment of 2D materials such as graphene and molybdenum disulfide (MoS2) with the insertion of hexagonal boron nitride (h-BN) and plasmonic nanoparticles. All these approaches have shown performance improvement of photodetectors for self-powering applications. A comprehensive analysis encompassing 2D material characterization, theoretical and numerical modelling, device physics, fabrication and characterization of photodetectors with graphene/MoS2 and graphene/h-BN/MoS2 heterostructures with plasmonic effect is presented with potential leads to new research opportunities.
Highlights
Light detection mechanism was introduced back in 1887 when Heinrich Hertz discovered that electrodes generate electric sparks when illuminated with ultraviolet light.This was supported with Max Planck’s suggestion that energy carried by electromagnetic fields can be quantized as discrete packets, known as photons or quanta, while studying black-body radiation in 1900
This review emphasizes photodetectors, other devices such as transistors and solar cells with graphene/MoS2 or graphene/hexagonal boron nitride (h-BN)/MoS2 heterostructures are included to understand the behaviors and physics of these heterostructures, because this review aims to study the impact of material structuring and attribution of plasmonic effects towards the electrical and optical properties, as well as the photovoltaic effect on graphene/MoS2 -based devices as a path for self-powering application
Based on these band diagrams, it can be concluded that h-BN layer acted as a barrier for electrons that suppressed the dark current and allowed hole tunnelling during illumination that contributed to a high Ion /Ioff ratio, which was supported by the work done in [36]
Summary
Light detection mechanism was introduced back in 1887 when Heinrich Hertz discovered that electrodes generate electric sparks when illuminated with ultraviolet light. The separation of photogenerated carriers in the P–N and Schottky junction photodetector types rely on the built-in potential of the active region materials, whereas the PEC type photodetector performance is dependent on the energy barrier between the electrode materials and electrolyte In this case, the response mechanism of self-powered photodetectors does not utilize an external biasing and is totally dependent on the light source that illuminates the device. Since the graphene/h-BN/MoS2 heterostructures have potential in self-powering photodetectors, further studies must be continued to tailor the device structures and modify the behavior of these materials for optimal performance, which is crucial for self-powered photodetectors because these advanced devices are expected to detect the smallest light signal without relying on external biasing. MoS2 /h-BN/graphene photodetector and the outlook of this study for the future
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