Newsfeeds
Journal of Physics D: Applied Physics - latest papers
Latest articles for Journal of Physics D: Applied Physics
-
Defect-state engineering via moderate W doping for high-performance solution-processed SnWO/Si heterojunction photodetectors
Defect states in oxide/Si heterojunction photodetectors play a critical role in governing carrier transport and transient photoresponse behaviors; however, effectively manipulating these defect states to achieve optimized device performance remains a significant challenge. Herein, solution-processed tungsten-doped tin dioxide (SnWO)/Si heterojunctions were fabricated to systematically investigate the impact of W doping. An optimal 2 at.% W concentration significantly enhances film uniformity and optimizes defect-mediated transport, yielding a photocurrent-to-dark current ratio of 314.3, a responsivity of 0.4 A W−1, and a specific detectivity of 6.3 × 1010 Jones under 450 nm illumination at −3 V. Furthermore, W doping modulates the transient photoresponse behaviors, and the phenomena ranging from fast response through spiky overshoot to slow relaxation are tentatively attributed to defect-mediated carrier dynamics. Specifically, the initially empty shallow traps allow transport under the nearly full internal field, giving an overshoot; their subsequent filling partially screens the internal field and returns the current to the steady state. Deep traps, in contrast, capture and slowly release a large fraction of the photocarriers, delaying the photocurrent buildup. After 90 d of ambient storage, both the defect-related and adsorbed oxygen components increase, indicating a reconstruction of the surface states and, in turn, a corresponding change in the transient photoresponse characteristics. Similarly, excessive doping exacerbates structural disorder and introduces recombination centers, ultimately impairing device performance.
-
Progress in the application of atomic layer deposition technology in novel microchannel plates
Microchannel plates (MCPs), as core electron multiplication devices, play a key role in particle physics, space exploration, and low-light imaging. Traditional lead-silicate glass MCPs are limited by material selection, difficulty in independently optimizing resistivity and secondary electron emission (SEE) yield, and challenges in fabricating large-area devices with small pore sizes. The introduction of atomic layer deposition (ALD) technology has provided a new technological route for overcoming these bottlenecks. This article systematically reviews the research progress of ALD-MCPs. First, the theoretical design and fabrication principles of ALD-MCPs are described, with particular emphasis on the calculation basis for the bulk resistivity of the conductive layer and the thickness of the emission layer, as well as the structural design. Second, the research progress of composite thin-film systems for conductive layers, including ZnO/Al2O3 and W/Al2O3-Mo/Al2O3, is discussed in detail in terms of resistivity regulation, stability, and applications. In addition, the gain performance and stability of Al2O3, MgO, and their composite films as SEE layers are analyzed. By separating the MCP substrate from the functional layers through ALD technology, ALD-MCPs exhibit significant advantages, including high electron gain, low dark count rate, long lifetime, and tunable resistivity, thereby laying a technical foundation for the development of novel MCP photodetectors with high resolution, high signal-to-noise ratio, and large area.
-
Enhanced selective production of nitrate in a gas–liquid phase dielectric barrier discharge reactor
A dual-chamber gas–liquid phase dielectric barrier discharge (DBD) reactor with tri-electrodes was designed for air-fed nitrogen fixation (NF). Air was activated in the gas-phase discharge chamber to produce nitrogen oxides (NOx), and these NOx species continued to synthesize aqueous nitrate species in the gas–liquid discharge chamber. The effect of electrode configuration, applied voltage, air flow rate, initial solution pH and electric discharge duration on the concentration, selectivity of nitrate/nitrite/ammonia, total nitrogen concentration and energy yield (EY) of NF was studied. The results showed that the DBD reactor with tri-electrodes efficiently produced microdischarges for N2 fixation with high nitrate selectivity at a higher applied voltage. The initial pH of the water in the lower discharge chamber had little effect on the input power but a significant impact on the transfer and conversion of gaseous NOx into aqueous nitrate, and a weak alkaline pH was more favorable for total nitrogen accumulation. Meanwhile, the input air flow rate in the DBD reactor and the water volume in the lower discharge chamber showed an optimum value, and the EY of total NF reached a maximum of 0.84 g kWh−1 at an initial solution pH 11 and water volume of 35 ml. The optical emission spectrum in the discharge regions indicated that the NF results at different applied voltages and air flow rates can be attributed to their influence on the production of N2*, N2+ and •OH, and the experiments including electron quenching and dry air discharge indicated that NH4+ was mainly produced via the reduction of N2 by hydrated electrons.
-
Enhanced photovoltaic response in Mn-doped BiFeO3-based perovskite solar cells
Prospects of organic-inorganic lead-halide perovskites in solar cell applications are limited by their notorious ambient instability vis-à-vis performance degradation and lead toxicity. Isoelectronic bismuth-based oxide perovskites with suitable optoelectronic properties could be plausible alternatives. Here we show that manganese-doping in bismuth ferrite (BiFeO3 or BFO) tailors the optoelectronic properties suitable for the absorber layer in a perovskite solar cell. We study the crystal structure, surface morphology, and optoelectronic properties of solution deposited thin films (thickness, 250–350 nm) of pristine and Mn-doped BFO (BFMO) from the perspective of photovoltaic applications. Both the systems exhibit rhombohedral R3c symmetry, an optical absorption coefficient, ∼105 cm−1 throughout the visible range, and a charge carrier concentration ∼1018−19 cm−3. Mn-doping demonstrates a small direct bandgap reduction in BFO from 2.6 to 2.5 eV. Ultraviolet photoelectron spectroscopy measurements determine the positions of the band edges (valence band maximum and conduction band minimum), required for the selection of carrier transport layers. A BFMO-based solar cell, FTO/SnO2/BFMO/Spiro-OMeTAD/Ag achieves a power conversion efficiency of 1.92%, in contrast to negligible response in the BFO-based device. We predict that BFMO with superior optoelectronic properties can manifest a significantly high conversion efficiency with precise defect control.
-
Spectrally selective optical, hot-electron, and photothermal effects in planar Tamm plasmon nanostructures
Multifunctional photonic nanostructures integrating optical filtering, hot-electron photodetection, and photothermal conversion are highly desirable for advanced optoelectronic and energy harvesting systems. Nevertheless, it remains challenging to achieve synchronous spectral-selective optical, electrical, and thermal responses in a single nanostructure. This work demonstrates that planar Tamm plasmon nanostructures can achieve simultaneous optical, electrical, and thermal spectral selectivity. A multilayer design, consisting of a Ge/MgF2 distributed Bragg reflector on a silver film, achieves near-perfect absorption (∼99%) at 1660 nm with a narrow full width at half maximum (∼32 nm). This resonance induces intense electromagnetic confinement at the Ag/Ge interface, resulting in a wavelength-selective hot-electron photoresponsivity of 35 mA W−1 and a peak local temperature of 75.4 °C under resonant illumination. Optical and thermal responses all exhibit matched spectral selectivity, confirming the structure’s multifunctional capabilities. The device is fully planar and compatible with lithography-free fabrication, offering practical advantages for integrated optoelectronic and energy-conversion systems. The study establishes a new route to integrate wavelength-selective filtering, hot-electron photodetection, and photothermal conversion within a single planar nanostructure as a high-performance platform.