Infrared avalanche photodiodes from bulk to 2D materials

Abstract

Avalanche photodiodes (APDs) have drawn huge interest in recent years and have been extensively used in a range of fields including the most important one—optical communication systems due to their time responses and high sensitivities. This article shows the evolution and the recent development of AIIIBV, AIIBVI, and potential alternatives to formerly mentioned—“third wave” superlattices (SL) and two-dimensional (2D) materials infrared (IR) APDs. In the beginning, the APDs fundamental operating principle is demonstrated together with progress in architecture. It is shown that the APDs evolution has moved the device’s performance towards higher bandwidths, lower noise, and higher gain-bandwidth products. The material properties to reach both high gain and low excess noise for devices operating in different wavelength ranges were also considered showing the future progress and the research direction. More attention was paid to advances in AIIIBV APDs, such as AlInAsSb, which may be used in future optical communications, type-II superlattice (T2SLs, “Ga-based” and “Ga-free”), and 2D materials-based IR APDs. The latter—atomically thin 2D materials exhibit huge potential in APDs and could be considered as an alternative material to the well-known, sophisticated, and developed AIIIBV APD technologies to include single-photon detection mode. That is related to the fact that conventional bulk materials APDs’ performance is restricted by reasonably high dark currents. One approach to resolve that problem seems to be implementing low-dimensional materials and structures as the APDs’ active regions. The Schottky barrier and atomic level thicknesses lead to the 2D APD dark current significant suppression. What is more, APDs can operate within visible (VIS), near-infrared (NIR)/mid-wavelength infrared range (MWIR), with a responsivity ~80 A/W, external quantum efficiency ~24.8%, gain ~105 for MWIR [wavelength, λ = 4 μm, temperature, T = 10–180 K, Black Phosphorous (BP)/InSe APD]. It is believed that the 2D APD could prove themselves to be an alternative providing a viable method for device fabrication with simultaneous high-performance—sensitivity and low excess noise.

Broadband Flexible Photodetectors Based on CdSxSe1–x/PbI2 Heterojunctions

“…This suggests that they may be attractive for high voltage applications. 40 The possible working mechanism of these VPDs can be explained using the energy band diagrams shown in Figure 3c and d. Considering the work function difference (Φ CdSd x Sed 1−x = 4.47 eV and Φ PbId 2 = 4.7 eV) 41 determined from ultraviolet photoelectron spectroscopy (Figure S8 in the SI), we suggest that a type-II heterojunction is formed between CdS x Se 1−x and PbI 2 .…”

Van der Waals Gate-Induced Ultrafast Photoresponse in a 2D PdPSe-Based Photodetector

“…Conversely, when a forward bias is applied, majority carriers readily traverse the junction region, resulting in a response time that closely aligns with the characteristics of the material itself. Avalanche photodiodes possess the ability to achieve heightened sensitivity and swifter response; however, they also exhibit increased noise levels as a result of the stochastic characteristics inherent in the avalanche process . Hence, it is crucial to devise a novel approach that can simultaneously enhance the photoresponsivity and response speed while eliminating the limitations imposed by bias voltage.…”

“…Avalanche photodiodes possess the ability to achieve heightened sensitivity and swifter response; however, they also exhibit increased noise levels as a result of the stochastic characteristics inherent in the avalanche process. 24 Hence, it is crucial to devise a novel approach that can simultaneously enhance the photoresponsivity and response speed while eliminating the limitations imposed by bias voltage.…”

Efficient Carrier Multiplication in Self-Powered Near-Ultraviolet γ-InSe/Graphene Heterostructure Photodetector with External Quantum Efficiency Exceeding 161%

“…Efficient CM induced by the high-energy photons in 2D materials shows tremendous potential for constructing ultrahigh-responsivity UV photodetectors with low power consumption, contrasting with photomultiplier tubes that require a high-power supply. 27,28 However, the existing efforts using CM to significantly enhance the self-powered photodetector performances are extremely scarce. 29−31 This is mainly because of the fact that the Gr and other 2D materials at atomic-scale thickness have limited light absorption, resulting in an inadequate photocurrent gain even based on the CM effect.…”

“…Taking Gr for example, , high-energy photons in the UV region can induce more steps of impact excitation cascade, resulting in a more significant CM effect and higher efficiency. Efficient CM induced by the high-energy photons in 2D materials shows tremendous potential for constructing ultrahigh-responsivity UV photodetectors with low power consumption, contrasting with photomultiplier tubes that require a high-power supply. , However, the existing efforts using CM to significantly enhance the self-powered photodetector performances are extremely scarce. − This is mainly because of the fact that the Gr and other 2D materials at atomic-scale thickness have limited light absorption, resulting in an inadequate photocurrent gain even based on the CM effect. Moreover, it remains a challenge to efficiently transfer the photogenerated high-energy carriers into the 2D materials without cooling, even with the addition of a light-absorbing layer.…”