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The atomic layer etching of molybdenum disulfides using low-power oxygen plasma
摘要： The layered removal mechanisms of molybdenum disul?des (MoS2) using low-power oxygen plasma are investigated in this paper. After the low-power oxygen plasma treatment, the topmost MoS2 layer is completely oxidized. The weaker adhesion of Mo oxides with MoS2 surfaces would lead to the detachment of the topmost oxidized MoS2 layer from the underlying MoS2 ?lms. Since MoS2 is insoluble and Mo oxides are soluble in water, an additional dipping procedure of the sample in de-ionized water will help with the complete detachment of the topmost oxidized MoS2 layer. With a re-sulfurization procedure after the removal process, the partially oxidized MoS2 ?lm remaining on the substrate can be recovered back to a complete MoS2 ?lm. Both optical and electrical characteristics of the MoS2 ?lms can be maintained after the removal procedure. By repeating the same procedure, a layer-by-layer removal of MoS2 is demonstrated, which provides an easy and fast approach to determine the number of layers of the 2D material.
关键词： layered removal,oxygen plasma,layer number controllability
更新于2025-11-14 17:03:37
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Growth Condition-Oriented Defect Engineering for Changes in Au–ZnO Contact Behavior from Schottky to Ohmic and Vice Versa
摘要： ZnO has the built-in characteristics of both ionic and covalent compound semiconductors, which makes the metal–ZnO carrier transport mechanism quite intricate. The growth mechanism-centric change in ZnO defect density and carrier concentration also makes the contact formation and behavior unpredictable. This study investigates the uncertainty in Au–ZnO contact behavior for application-oriented research and the development on ZnO nanostructures. Herein, we explain the phenomenon for how Au–ZnO contact could be rectifying or non-rectifying. Growth method-dependent defect engineering was exploited to explain the change in Schottky barrier heights at the Au–ZnO interface, and the change in device characteristics from Schottky to Ohmic and vice versa. The ZnO nanorods were fabricated via aqueous chemical growth (ACG) and microwave-assisted growth (MAG) methods. For further investigations, one ACG sample was doped with Ga, and another was subjected to oxygen plasma treatment (OPT). The ACG and Ga-doped ACG samples showed a quasi-Ohmic and Ohmic behavior, respectively, because of a high surface and subsurface level donor defect-centric Schottky barrier pinning at the Au–ZnO interface. However, the ACG-OPT and MAG samples showed a more pronounced Schottky contact because of the presence of low defect-centric carrier concentration via MAG, and the removal of the surface accumulation layer via the OPT process.
关键词： oxygen plasma treatment,nanorod,ZnO,crystal defects,microwave,metal-semiconductor contact
更新于2025-09-23 15:22:29
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Induced Photonic Response of ZnO Nanorods Grown on Oxygen Plasma-Treated Seed Crystallites
摘要： We examined the influence of O2 plasma treatment for the ZnO seed layer (SL) crystallites on the material characteristics of ZnO nanorods (NRs) synthesized by the hydrothermal method. Diode photocurrent and photo-response transient characteristics of the p-Si/n-ZnO-NR heterojunction-based ultraviolet (UV) photodetectors were also examined according to the plasma treatment for the SLs. The superior optical properties of NRs were measured from the photoluminescence by exhibiting 4.6 times greater near-band edge emission when grown on the O2-plasma-treated SL. The degree of (002) orientation of the NR crystals was improved from 0.67 to 0.95, as revealed by X-ray diffraction analysis, and a higher NR surface density of ~80 rods/μm2 with a smaller mean diameter of 65 nm were also observed by the SL modification using plasma-treatment. It was shown by X-ray photo-electron spectroscopy that this improvement of NR crystalline quality was due to the recovery of stoichiometric oxygen with significant reduction of oxygenated impurities in the SL crystals and the subsequent low-energy growth mode for the NRs. UV PDs fabricated by the proposed SL plasma treatment technique showed significantly enhanced UV-to-dark current ratio from 2.0 to 83.7 at a forward bias of +5 V and faster photo-response characteristics showing the reduction in recovery time from 16 s to 9 s.
关键词： photoluminescence,surface defects,oxygen plasma,ZnO seed crystals,hydrothermal
更新于2025-09-23 15:21:01
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Surface Engineering of Low-Temperature Processed Mesoporous TiO <sub/>2</sub> via Oxygen Plasma for Flexible Perovskite Solar Cells
摘要： A major problem in the application of mesoporous TiO2 as an electron transport layer for flexible perovskite solar cells is that a high temperature sintering process is required to remove organic additives from the TiO2 layer. A facile oxygen plasma process is herein demonstrated to fabricate mesoporous structured perovskite solar cells with significant photovoltaic performance at low temperatures. When the low-temperature processed TiO2 layer is modified via oxygen plasma, the organic additives in the TiO2 layer that hinder the charge transport process are successfully decomposed. The oxygen plasma treatment improves the wettability and infiltration of the perovskite layer and also passivates the oxygen vacancy related traps in TiO2. Hence, the oxygen plasma treatment evidently enhances charge extraction and transport, thereby improving photovoltaic performance and decreasing hysteresis.
关键词： Mesoporous TiO2,Flexible solar cell,Oxygen plasma,Low-temperature processed TiO2,Perovskite solar cell
更新于2025-09-23 15:19:57
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Gianta??Enhanced SnS <sub/>2</sub> Photodetectors with Broadband Response through Oxygen Plasma Treatment
摘要： Layered tin disulfide (SnS2) is a vital semiconductor with versatile functionality due to its high carrier mobility and excellent photoresponsivity. However, the intrinsic defects Vs (sulfur vacancies), which cause Fermi level pinning (significant metal contact resistance), hinder its electrical and optoelectrical performance. Herein, oxygen plasma treatment is employed to enhance the optoelectronic performance of SnS2 flakes, which results in artificial sub-bandgap in SnS2. Consequently, the broadband photosensing (300–750 nm) is remarkably improved. Specifically, under 350 nm illumination, the O2-plasma-treated SnS2 photodetector exhibits an enhanced photoresponsivity from 385 to 860 A W?1, the external quantum efficiency and the detectivity improve by one order of magnitude as well as increase the photoswitching response improvement by two orders of magnitude for both rising (τr) and decay (τd) time. This artificial sub-bandgap can both improve the photoresponse and broaden the response spectra, which paves a new path for the applications of optoelectronics.
关键词： broadband photodetection,2D materials,SnS2 photodetectors,oxygen plasma treatment
更新于2025-09-23 15:19:57
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Ultraviolet Photodetecting and Plasmon-to-Electric Conversion of Controlled Inkjet-Printing Thin-Film Transistors
摘要： Direct ink-jet printing of a zinc-oxide-based thin-film transistor (ZnO-based TFT) with a three-dimensional (3-D) channel structure was demonstrated for ultraviolet light (UV) and visible light photodetection. Here, we demonstrated the channel structures by which temperature-induced Marangoni flow can be used to narrow the channel width from 318.9 ± 44.1 μm to 180.1 ± 13.9 μm via a temperature gradient. Furthermore, a simple and efficient oxygen plasma treatment was used to enhance the electrical characteristics of switching ION/IOFF ratio of approximately 105. Therefore, the stable and excellent gate bias-controlled photo-transistors were fabricated and characterized in detail for ultraviolet (UV) and visible light sensing. The photodetector exhibited a superior photoresponse with a significant increase of more than 2 orders of magnitude larger drain current generated upon UV illumination. The results could be useful for the development of UV photodetectors by the direct-patterning ink-jet printing technique. Additionally, we also have successfully demonstrated that a metal-semiconductor junction structure that enables plasmon energy detection by using the plasmonic effects is an efficient conversion of plasmon energy to an electrical signal. The device showed a significant variations negative shift of threshold voltage under different light power density with exposure of visible light. With the ZnO-based TFTs, only ultraviolet light detection extends to the visible light wavelength.
关键词： visible light photodetection,plasmon energy detection,ink-jet printing,zinc-oxide-based thin-film transistors,oxygen plasma treatment
更新于2025-09-19 17:13:59
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Reprint of “Oxygen-plasma processed Spiro-OMeTAD toward high performance for perovskite solar cell”
摘要： Efficient perovskite solar cell was achieved using a small hole transport material, Spiro-OMeTAD, after oxygen plasma treatment. It was demonstrated that the plasma treatment of hole transport layer for the solids state perovskite solar cell was enhanced power conversion efficiency. Reason for enhancing the cell performance of solar cell was good match of homo energy level between perovskite and Spiro-OMeTAD. It leads to transfer well hole carrier at Active/HTL interface. This study obtained highly improved performance by a current density of 25.4 mA/cm2, an open-circuit voltage of 1.02 V, and a fill factor of 60.2%, which resulted showed above 15% of cell efficiency.
关键词： Perovskite solar cell,Oxygen plasma,Plasma treatment,Aging effect
更新于2025-09-16 10:30:52
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Remarkable improved solar transmission of VO2 smart windows by partial controlled oxygen plasma bombarding
摘要： The vanadium dioxide (VO2) based smart windows are developed to reduce energy consumption and improve thermal and visual comfort by controlling the solar flux entering into a building. In this paper, the solo oxygen plasma bombarding is adopted at low temperature (30 °C) for the solar transmission improvement in VO2 smart windows, which helps to overcome the constraints of destruction in toughened VO2 windows by annealing. Various oxygen flow rates were used to assist the plasma to identify the influence and mechanism in thermochromic VO2 films for the first time. The oxygen plasma treatment leads to an effective composition modulation and microstructure reconstruction in the VO2 films to create new functionalities. The conversion between VO2 and V2O5 can be controlled and maintained stable during the O2 flow range of 120–160 sccm (called stable zone). Favorable results are achieved in the stable zone compared with the untreated VO2 films, the relative improvement of luminous transmission T lum (380–780 nm) is 44%, meanwhile, the increase of T sol (380–2500 nm) is 30% with a negligible decrease of 1.5% in ΔT sol. Additionally, the solar transmission of VO2 films can be emphatically improved with preserved phase transition behaviors. It reveals that the proposed technique is simple, efficient and performed with ease in working tolerance, and can be applied widely in the VO2 smart window field.
关键词： VO2 films,Energy-saving buildings,Solar transmittance,Smart windows,Oxygen plasma
更新于2025-09-16 10:30:52
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Influence of External Input Parameters on Species Production in a Dual-Frequency Capacitively Coupled Radio-frequency Oxygen Plasma
摘要： The impact of some external input parameters on electron, ozone O3, negative O? and positive O2+ ions, metastable singlet delta-state O2(a1Δg) molecule and atomic oxygen O formation is investigated using a numerical simulation. A one-dimensional, self-consistent fluid model of a dual radio-frequency capacitively coupled discharge operating on pure oxygen is developed to explore the evolution of the species density profiles as functions of gas pressure pg, driving high-frequency fhf, inter-electrode gap distance d and driving voltage waveform Vhf. The proposed model incorporates five main species and 24 dominant reaction channels. Simulation results show that the time-averaged density profiles of electron, ozone O3, negative O? and positive O2+ ions decrease when the gas pressure increases. However, the density of the metastable singlet delta-state O2(a1Δg) molecule and atomic oxygen O increase when the gas pressure increases. The electron density significantly increases with increased fhf until a maximum peak is reached at 40.68 MHz, and then it drops almost linearly at frequencies greater than 40.68 MHz. However, the negative ions O? density increases over a range of frequencies from 27.12 to 67.80 MHz, then it decreases slightly as fhf increases further. Therefore, when fhf increases, it does enhance the production of the metastable O2(a1Δg) and the oxygen O atoms, whereas the O2+ density is decreased. It is also shown that an increase in the inter-electrode gap distance causes a noticeably decrease in the formation of the various species in the discharge. Furthermore, a significant increase in the atomic oxygen O and the metastable singlet delta-state O2(a1Δg) densities is displayed as Vhf increases. Comparisons are made with recent simulation models and experimental data, and a qualitative agreement is obtained.
关键词： Low-temperature plasma,Dual capacitively coupled oxygen plasma,Species production
更新于2025-09-12 10:27:22
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Recovery of cycling-induced endurance failed HfO <sub/><i>x</i> </sub> based memristive devices by utilizing oxygen plasma treatment
摘要： The oxygen ion (O2(cid:2)) loss effect during resistive switching (RS) cycles will inevitably lead to endurance degradation or even failure in oxide-based memristive devices. In this Letter, we propose an effective way to recover the cycling-induced endurance failed HfOx based memristive devices by utilizing oxygen plasma treatment (OPT). In the as-fabricated Pt/HfOx/Pt devices, a negative SET event is observed after consecutive normal RS cycles and eventually triggers endurance failure. The appearance of the intermediate resistance state at the initial stage of the negative SET cycle indicates a prominent reduction of the migration barrier of O2(cid:2), which accounts for the occurrence of negative SET after increasing cycles. Then, we recover the devices from endurance failure by moderate OPT, which can supply the available O2(cid:2) in RS cycles. More importantly, the first recovered devices after endurance failure can be recovered again through OPT, which better proves the validity of the recovery method. This study could provide an effective approach for understanding and addressing the cycling-induced endurance failure issue in oxide-based memristive devices.
关键词： oxygen plasma treatment,HfOx,endurance failure,memristive devices,resistive switching
更新于2025-09-12 10:27:22