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Monolayer Attachment of Metallic MoS <sub/>2</sub> on Restacked Titania Nanosheets for Efficient Photocatalytic Hydrogen Generation
摘要： Monolayer attachment of metallic MoS2 (1T) on restacked titania (Ti0.87O2 0.52?) nanosheets was attained via a facile two-step flocculation process of their colloidal suspensions with the aid of the difference in critical H+ concentrations required for inducing flocculation of the respective nanosheets. The process produced porous flaky aggregates of restacked Ti0.87O2 0.52? nanosheets covered with monolayer MoS2, which serves as the electron collector and provides abundant catalytically active sites for proton reduction reaction. The MoS2-modified restacked-Ti0.87O2 0.52? nanosheets showed a remarkably high photocatalytic efficiency for hydrogen generation (1.2 mmol h-1 g-1), being superior to those of the restacked Ti0.87O2 0.52? nanosheets and P25-TiO2 nanoparticles conventionally modified with MoS2 (0.38, and 0.4 mmol h-1 g-1, respectively). The extensive molecular-level interfacial coupling of Ti0.87O2 0.52?/MoS2 nanosheets facilitates efficient charge separation and fast electron transfer, resulting in the significantly enhanced photocatalytic activity.
关键词： 2D heterointerface,photocatalysis,hydrogen evolution,two-step flocculation process,monolayer co-catalyst
更新于2025-09-23 15:21:21
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Effects of Doping of Bragg Reflector Layers on the Electrical Characteristics of InGaAs/GaAs Metamorphic Photovoltaic Converters
摘要： The current–voltage characteristics of InxGa1 – xAs/GaAs metamorphic photovoltaic converters with built-in n-InGaAs/InAlAs Bragg reflectors are studied at an indium content of x = 0.025–0.24. The series resistance of the heterostructures is measured in the temperature range from 90 to 400 K. It is found that a sharp rise in the resistance of silicon-doped reflectors with an increasing fraction of In is due to weak activation of the donor impurity in InAlAs–n:Si layers. As a result, the energy barriers for majority carriers are formed in the latter, with a height of 0.32–0.36 eV and a substantial width. To suppress this effect, the technology of the Te doping of n-InGaAs/InAlAs Bragg reflectors is developed, which reduces the series resistance by five orders of magnitude. This makes it possible to keep the fill factor of the current–voltage characteristic above 80% up to current densities of 2 A/cm2. Values exceeding 85%, achieved for the quantum efficiency, indicate that the “memory” and tellurium segregation effects characteristic of this kind of impurity are suppressed.
关键词： InAlAs,resistive loss,doping,Bragg reflector,photovoltaic converter,heterointerface,InGaAs
更新于2025-09-23 15:21:01
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Plasmonic gold nanorods mediated p-BFCrO/n-rGO heterojunction in realizing efficient ferroelectric photovoltaic devices
摘要： In this work, we introduce a chemically synthesised lead-free ferroelectric thin film 2% Cr doped BiFeO3 (BFCrO) for possible photovoltaic (PV) applications. The first set of PV devices were fabricated onto ITO/glass electrode by utilizing BFCrO as an active material and Pt as top electrode. The obtained ferroelectric and electrical results were systematically compared with the conventional BFO and the BFCrO device was found to be a potential one. To further enhance the PV performance, highly conducting n-type reduced graphene oxide (rGO) was heterogeneously employed as an electron transport layer (ETL) in between ITO and BFCrO. Surprisingly, the JSC was significantly improved by 1000 times along with amended VOC and FF as compared to the standalone BFCrO device. Furthermore, an attempt has been made to embed plasmonic Au nanorods (NRs) in between rGO and BFCrO, which alleviates the absorbance in heterojunction through localized surface plasmonic effect, ultimately offered remarkable PV performances than conventional BFO one. The Au NRs based BFCrO/rGO PV device exhibited an increased VOC and JSC of 0.63 V and 2.56 mA/cm2, respectively as compared to the BFCrO/rGO device with VOC (0.56 V) and JSC (1.54 mA/cm2). Effort was devoted to establish ferroelectricity in BFCrO and the effect of positive and negative polarizations on J-V measurements were observed in with or without Au NRs based devices. The modulation in charge transport with polarization field and improved photoresponse were explained by projecting a band diagram, which also provides a comprehensive understanding on the operation principle of the fabricated devices.
关键词： Ferroelectric polarization,Heterointerface,Photovoltaic effect,Electron transport layer,Plasmon resonance
更新于2025-09-19 17:13:59
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Polarization induced two-dimensional electron gas in ZnO/ZnMgO Heterointerface for High-performance enhanced UV photodetector
摘要： The spontaneous formation of two-dimensional electron gas (2DEG) with a high carrier density (~1018 cm-3) was achieved at a ZnO/Mg0.2Zn0.8O interface grown using a facile radio-frequency magnetron sputtering system on a quartz substrate. Compared with Mg0.2Zn0.8O ultraviolet (UV) photodetectors (PDs) with and without a ZnO buffer layer, the PD based on ZnO/Mg0.2Zn0.8O bilayer films exhibited not only sensitivity to dual wavelength in the UV region, but also significantly enhanced spectral responsivity, photocurrent-to-dark current ratio (107), specific detectivity (1014), and UV/visible rejection ratio of about four orders of magnitude at a low operating voltage bias. Induced by 2DEG, the external quantum efficiency (EQE) of photodetector reached 14858% at 10 V, indicating that a considered high gain was achieved in the device based on this heterojunction architecture. The gain mechanism was further demonstrated by polarization induction and band bending in detail. This application of 2DEG in a practical detector offers a novel and effective approach for the substantial improvement in the high-performance of ZnO/Mg0.2Zn0.8O dual-band UV PDs.
关键词： two-dimensional electron gas,polarization,high-performance UV PDs,ZnO/Mg0.2Zn0.8O heterointerface,gain
更新于2025-09-12 10:27:22
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Anomalous arsenic diffusion at InGaAs/InP interface
摘要： The anomalous arsenic (As) diffusion at the In0.53Ga0.47As/InP interface grown by solid source molecular beam epitaxy has been reported in this work. Heterointerface samples were grown using group-V switches of P2 to As2 or to As4. High-resolution X-ray diffraction (XRD), photoluminescence (PL), 3-D atom probe (3DAP) and high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) data have shown that, an up to hundred-nanometer-thick composition-graded InAsyP1-y layer formed in the InP buffer layer for the sample grown by P2 to As2. This observation demonstrates a rapid replacement of P by As atoms at the heterointerface and a deep As diffusion into the lower InP buffer. In contrary, a sharper heterointerface without the composition-graded layer was obtained in the sample grown using P2 to As4. These findings give insight into the distinct properties of different As species in the InGaAs/InP interface growth.
关键词： atomic diffusion,InGaAs/InP,P/As exchange,heterointerface
更新于2025-09-04 15:30:14
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Atomic scale depletion region at one dimensional MoSe <sub/>2</sub> -WSe <sub/>2</sub> heterointerface
摘要： Lateral heterojunctions based on two dimensional (2D) transition metal dichalcogenides (TMDCs) potentially realize monolayer devices exploiting 2D electronic structures and the functions introduced by the presence of 1D heterointerfaces. Electronic structures of a lateral MoSe2-WSe2 junction have been unveiled using scanning tunneling microscopy and spectroscopy. A smooth and narrow depletion region exists despite a defect-rich heterointerface deviating from the preferred zigzag orientations of the TMDC lattice. From the characteristics of the depletion region, a high carrier concentration and high internal electric fields are inferred, offering to benefit designs of lateral TMDC devices.
关键词： depletion region,MoSe2-WSe2,heterointerface,scanning tunneling microscopy,scanning tunneling spectroscopy,TMDCs
更新于2025-09-04 15:30:14