Responsivity

About: Responsivity is a research topic. Over the lifetime, 9918 publications have been published within this topic receiving 186118 citations.

Construction of a β-Ga2O3-based metal–oxide–semiconductor-structured photodiode for high-performance dual-mode solar-blind detector applications

Abstract: Sensitive, high photoresponse and energy-saving detectors are urgently required to monitor solar-blind UV signals. The impressive advantages of Ga2O3 in this field give rise to extensive research and studies. A high-performance dual-mode β-Ga2O3 metal–oxide–semiconductor (MOS)-structured photodiode solar-blind detector is introduced. The device shows a rectifying ratio of 2 × 103 at ±10 V with a low reverse leakage current of 1.05 pA. Under 1.1 μW cm−2 254 nm light illumination, it provides a specific detectivity (D*) of ∼1013 Jones, a high responsivity (R) of 189.89/3.96 A W−1 and a high external quantum efficiency (EQE) of 92 879%/1936% at 10/−10 V, suggesting a high-resolution and sensitive detection in the dual operating (photoconductive/depletion) mode. At zero bias, it exhibits an ultralow dark current of 4.2 pA, an R of 33.48 mA W−1, an EQE of 16.37% and a D* of 1.83 × 1011 Jones, yielding a self-powered operation owing to the enhanced built-in electrical field. Moreover, at ±200 V, the device still avoids breakdown and displays an R of 3930.55 A W−1 and a D* of 1015 Jones, allowing harsh environmental operation. In addition, no obvious degeneration was observed after two months storage. The dual-mode photodiode promises to perform solar-blind detection along with sensitive, stable and self-powered performances.

High-Responsivity Mid-Infrared Black Phosphorus Slow Light Waveguide Photodetector

Abstract: DOI: 10.1002/adom.202000337 transparency windows and the characteristic absorption bands of abundant biochemical molecules.[1,2] Thus, the MIR possesses enormous potential for various applications, ranging from thermal imaging for homeland security and missile guidance to label-free absorption spectroscopy for environmental monitoring, industrial process control, and medical diagnostics.[3–7] The monolithic integration of waveguides and photodetectors enables miniaturization of photonic systems and is an essential step towards the realization of on-chip sensing systems.[8,9] Moreover, the waveguide photodetector provides another advantage of decoupling the optical absorption length from the absorption material thickness, thereby offering more flexibility in the device geometry design for performance optimization.[10] However, the development of MIR waveguide photodetectors is still in infancy, which is primarily hindered by the huge lattice mismatch between silicon (Si) and typical narrowbandgap semiconductors for MIR photodetection, such as II–VI,[11] III–V,[12,13] and IV–VI[14] alloys. 2D materials, whose layered lattice structures ease their monolithic integration with Si, are regarded as promising alternatives to overcome this bottleneck. Compared with graphene that suffers from large dark current due to its zero bandgap,[15–18] the lately rediscovered black phosphorus (BP) has been attracting intense research interest for realizing high-performance MIR photodetection because of its narrow direct bandgap of around 0.3 eV in bulk form corresponding to a cut-off wavelength of 4.13 μm.[19,20] Beyond 4.13 μm, through alloying with arsenic[21,22] or exploring the Stark effect by applying a vertical electric field,[23] BP photoresponses have been extend to around 8 μm. Various MIR BP photodetectors with free-space geometry have been reported.[24–28] In addition, several BP waveguide photodetectors have been demonstrated in the near-infrared and the short-wavelength infrared.[29,30] Recently, MIR grating-couplerintegrated BP photodetectors were reported with a high responsivity of 1.333 A W−1 at 3.78 μm in a 40 nm zigzag device under 1 V bias and 1.193 μW incident power.[31] Nevertheless, the high responsivity was obtained at the expense of a long device length (i.e., channel width) of 80 μm. Further miniaturization of the photodetector is expected to improve the operation speed, the signal-to-noise ratio (SNR), and the internal quantum Black phosphorus (BP) offers unique opportunities for mid-infrared (MIR) waveguide photodetectors due to its narrow direct bandgap and layered lattice structure. Further miniaturization of the photodetector will improve operation speed, signal-to-noise ratio, and internal quantum efficiency. However, it is challenging to maintain high responsivities in miniaturized BP waveguide photodetectors because of reduced light–matter interaction lengths. To address this issue, a method utilizing the slow light effect in photonic crystal waveguides (PhCWGs) is proposed and experimentally demonstrated. A shared-BP photonic system is proposed and utilized to fairly and precisely characterize the slow light enhancement. Close to the band edge around 3.8 μm, the responsivity is enhanced by more than tenfold in the BP photodetector on a 10 μm long PhCWG as compared with the counterpart on a subwavelength grating waveguide. At a 0.5 V bias, the BP PhCWG photodetector achieves a 11.31 A W−1 responsivity and a 0.012 nW Hz−1/2 noise equivalent power. The trap-induced photoconductive gain is validated as both the dominant photoresponse mechanism and the major limiting factor of the response speed. The BP slow light waveguide photodetector is envisioned to realize miniaturized high-performance on-chip MIR systems for widespread applications including environmental monitoring, industrial process control, and medical diagnostics.

Non-Equilibrium Devices For Infrared Detection

Abstract: A non-equilibrium mode of operation for semiconductor infrared photodetectors is proposed which will enable their cooling requirements to be substantially reduced. The operating temperature of 3-5 μm band detectors may be raised from - 200K to near ambient, whilst for the 8-12 μm band devices thermoelectric coolers can be considered in place of liquified nitrogen systems. The phenomena of minority carrier exclusion and extraction are utilised in order to maintain the densities of both carrier types well below the near intrinsic, equilibrium values associated with these elevated temperatures, with consequent improvements in responsivity and D.

High-Stability, Self-Powered Perovskite Photodetector Based on a CH3NH3PbI3/GaN Heterojunction with C60 as an Electron Transport Layer

Abstract: We reported first photodetectors based on a CH3NH3PbI3/GaN heterojunction with or without an electron transport layer (ETL). Through the investigation, the device without an ETL showed good sensitivity, high stability, and repeatability. Particularly, when C60 was applied as the ETL, the device showed a self-powered characteristic with high stability. The best self-powered device with 6 nm C60 displayed an on/off ratio of greater than 5000, peak responsivity of 0.198 A/W, and detectivity of 7.96 × 1012 cm Hz1/2/W, which is comparable with the other reports. The high performance mentioned above was attributed mainly to the C60 layer, which can reduce the density of trap states and passivate the grain boundaries of the CH3NH3PbI3 absorbing layer to facilitate intermolecular charge transport.