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Spectral responsivity and photoconductive gain in thin film black phosphorus photodetectors
摘要： We have fabricated black phosphorus photodetectors and characterized their full spectral responsivity. These devices, which are effectively in the bulk thin film limit, show broadband responsivity ranging from <400 nm to the ~3.8 μm bandgap. In the visible, an intrinsic responsivity >6 A/W can be obtained due to internal gain mechanisms. By examining the full spectral response, we identify a sharp contrast between the visible and infrared behavior. In particular, the visible responsivity shows a large photoconductive gain and gate-voltge dependence, while the infrared responsivity is nearly independent of gate voltage and incident light intensity under most conditions. This is attributed to a contribution from the surface oxide. In addition, we find that the polarization anisotropy in responsivity along armchair and zigzag directions can be as large as 103 and extends from the band edge to 500 nm. The devices were fabricated in an inert atmosphere and encapsulated by Al2O3 providing stable operation for more than 6 months.
关键词： Two-dimensional materials,Mid-infrared,Photodetectors,Black phosphorus,Photoconductive gain
更新于2025-09-12 10:27:22
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Theoretical correlation and effect of annealing on the photoresponse of vertically strain-coupled In <sub/>0.5</sub> Ga <sub/>0.5</sub> As/GaAs quantum dot heterostructures
摘要： Here, we propose a di?erent approach for growing strain-coupled In0.5Ga0.5As quantum dot infrared photodetectors (QDIPs) with varying dot layer periodicity. Strain calculation is done throughout the quantum dot (QD) heterostructures, which has a signi?cant e?ect on the carrier probability density functions. The localization of the electron probability density function in each heterostructure has a strong correlation with the photoresponse. The con?ned electron wavefunction in the top QD layer of the optimized device heterostructure (trilayer QDIP having dot layer periodicity of three) would be useful for hyperspectral imaging applications owing to its narrow (8.67 meV) photoresponse. Rapid thermal annealing treatment was carried out on the trilayer QDIP to investigate the enhancement in its optoelectronic properties. The dark current density reduced by two orders, and the operating temperature increased by 30 °C for the 650 °C-annealed counterpart. Also, the responsivity enhanced by two times (2.05 A/W at ?1 V) for the annealed QDIP.
关键词： In0.5Ga0.5As,rapid thermal annealing,photoresponse,strain-coupled,quantum dot infrared photodetectors
更新于2025-09-12 10:27:22
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Variation of the photoluminescence spectrum of InAs/GaAs heterostructures grown by ion-beam deposition
摘要： This work reports on an experimental investigation of the influence of vertical stacking of quantum dots, the thickness of GaAs potential barriers, and their isovalent doping with bismuth on the photoluminescence properties of InAs/GaAs heterostructures. The experimental samples were grown by ion-beam deposition. We showed that using three vertically stacked layers of InAs quantum dots separated by thin GaAs barrier layers was accompanied by a red-shift of the photoluminescence peak of InAs/GaAs heterostructures. An increase in the thickness of the GaAs barrier layers was accompanied by a blue shift of the photoluminescence peak. The effect of isovalent Bi doping of the GaAs barrier layers on the structural and optical properties of the InAs/GaAs heterostructures was investigated. It was found that the Bi content up to 4.96 atom % in GaAs decreases the density of InAs quantum dots from 1.53 × 1010 to 0.93 × 1010 cm?2. In addition, the average lateral size of the InAs quantum dots increased from 14 to 20 nm, due to an increase in the surface diffusion of In. It is shown that isovalent doping of GaAs potential barriers by bismuth was accompanied by a red-shift of the photoluminescence peak of InAs quantum dots of 121 meV.
关键词： photoluminescence,semiconductors,quantum dot,ion-beam deposition,nanoheterostructures,infrared photodetectors
更新于2025-09-10 09:29:36
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Effects of barrier energy offset and gradient in extended wavelength infrared detectors
摘要： The extended wavelength infrared photodetectors are new class of III-V semiconductor heterojunction-based photodetectors that can detect incoming radiation with an energy significantly smaller than the minimum energy gap (Δ) at the heterojunction interface. Architecture of these photodetectors include a barrier-emitter-barrier epilayers sandwiched between highly doped ohmic top and bottom contact layers. An energy offset (????) between the barriers is necessary for the extended wavelength photodetection. In this work, we study the performance of extended wavelength infrared photodetectors with varying ???? and gradient of the potential barrier. Results indicate that the extended wavelength threshold varied slightly with varying both the gradient and offset. Spectral responsivity, however, increased with the increasing offset and decreased with increasing gradient.
关键词： Extended wavelength infrared photodetectors,III-V semiconductors,GaAs/AlGaAs heterostructures
更新于2025-09-09 09:28:46
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Low-Dimensional Materials and State-of-the-Art Architectures for Infrared Photodetection
摘要： Infrared photodetectors are gaining remarkable interest due to their widespread civil and military applications. Low-dimensional materials such as quantum dots, nanowires, and two-dimensional nanolayers are extensively employed for detecting ultraviolet to infrared lights. Moreover, in conjunction with plasmonic nanostructures and plasmonic waveguides, they exhibit appealing performance for practical applications, including sub-wavelength photon confinement, high response time, and functionalities. In this review, we have discussed recent advances and challenges in the prospective infrared photodetectors fabricated by low-dimensional nanostructured materials. In general, this review systematically summarizes the state-of-the-art device architectures, major developments, and future trends in infrared photodetection.
关键词： plasmonic waveguides,infrared photodetectors,nanostructures
更新于2025-09-04 15:30:14