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Enhanced electron field emission from nanocrystalline orthorhombic boron nitride films
摘要： Nanocrystalline orthorhombic boron nitride (oBN) thin films with an island-in-honeycomb morphology were prepared on graphite substrate by radio frequency (r.f.) magnetron sputtering. The Field emission (FE) measurement results indicated that the FE properties are significantly enhanced in oBN films compared to high quality cBN films, the turn-on electric field of oBN films is decreased from 17.0 V/μm to 6 V/μm, and the highest emission current density is increased from 2.8 × 10?? to 3 × 10?? A/cm2. The enhanced FE properties of the oBN films can be attributed to significant reduction in effective potential barrier caused by both protruded island-in-honeycomb morphology and honeycomb-like interconnected internal structure.
关键词： Semiconductors,Thin films,Electron field emission,Boron nitride,Physical vapour deposition
更新于2025-09-23 15:22:29
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A structural study of the growth of ZnO<sub>x</sub> thin films by thermal evaporation in vacuum followed by heat treatment in air
摘要： ZnO thin films were grown on glass slides by thermal evaporation of zinc powder in vacuum followed by heat treatment in air. The films were characterized by x-ray diffraction (xrd), Raman scattering and scanning electron microscopy (SEM). Xrd pattern for as-deposited thin film sample consists of hexagonal Zn structure with slight wurtzite ZnO texture. It is observed that the heat treatment at between 450 and 600 oC for 1 to 3 hours turns the xrd pattern almost completely to wurtzite ZnO structure. SEM micrographs display flakes like hexagonal button shaped grains for as-deposited thin film which turns to needle like nanometer size structures with heat treatment. The red shift of some vibrational modes in Raman spectra for as-deposited thin film relative to the heat treated films and the introduction of a line at around 582 cm-1 indicate that ZnO thin films have defects such as oxygen vacancies or zinc interstitials. The most intense Raman mode due to high frequency oxygen vibration for as-deposited zinc film is red-shifted by about 7 cm-1 relative to the heat treated films.
关键词： Thin films,ZnO,Physical vapour deposition
更新于2025-09-19 17:15:36
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Impact of pixel surface topography onto thin-film encapsulated top-emitting organic light-emitting diodes performances
摘要： Two di?erent designs of top-emitting green OLEDs (Organic Light-Emitting Diodes) have been studied. The ?rst one presents a planar OLED architecture. The second one presents an OLED having a topographic surface, so as to simulate a pixel partitioning of a display using an electrically insulating, 200 nm-thick, resist. It has been observed that the topography has a large impact on OLED performances. Studying devices using an ALD (Atomic Layer Deposition)-deposited Al2O3 barrier ?lm shows that topographic OLEDs have a lower stability under storage in 65 °C/85% RH conditions compared to planar ones, with a di?erence in ageing models between the two devices. As the ALD deposition technology has a high conformity, which implies that ALD-deposited Al2O3 barrier ?lms should be as good on topographic devices as on planar ones, we inferred that the topographic OLED Achilles’ heel lies rather in the OLED structure rather than in the Al2O3 encapsulation itself. Thus, topographic and planar unencapsulated OLEDs (without Al2O3) were studied: interestingly, it has been observed that planar OLEDs can live several weeks, while topographic OLEDs show a very short shelf lifetime (in laboratory atmosphere, at 21 °C/50% RH), of only a couple of hours. It will be shown that the topographic OLED surface tends to reduce the thickness of the PVD (Physical vapour Deposition)-deposited layers in the OLED, as this is expected for a non-conformal deposition PVD technique, on tapered angle regions of the resist (pixel edges). While this thickness variation would not be critical for thick electrodes, as for instance for bottom-emitting devices made on glass substrates, this thickness reduction turns out to be a critical point for the ultrathin, 15 nm, silver cathode, used as semi-transparent electrode in this top-emitting architecture and will therefore be discussed in the framework of using OLED top-emitting architectures in (micro)display technology.
关键词： Dark spots,Physical vapour deposition,Atomic layer deposition,Organic light-emitting diodes,Topography,Degradation
更新于2025-09-19 17:13:59
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Studies on the developing of Nano-Structured Cu2S film for photovoltaic application
摘要： Current efforts have been given to develop new photovoltaic materials to improve the efficiency with reducing cost. The factors that have been taken into account in developing new photovoltaic materials include: a suitable energy band gap, the possibility of depositing the material using low cost deposition methods, abundance of the elements and low environmental costs with respect to the synthesis of the elements, production, operation and disposal of modules. It’s been a long time that continuous efforts has been given to find out the most appropriate material to be employed as absorber material for solar cell and some advanced material has been proposed too as potential solar cell material. Here in our present study we have taken Cu2-xS as a suitable p-type absorber layer material but the formation of stable Cu2-xS film was being difficult task. Different researchers proposed different methods among them we have found the elemental stacked layer deposition method is one of the promising technique. But this technique requires further optimization on thickness and layer no’s to get the best result with required stoichiometry. With this context we have tried to optimize the thickness and layer no’s for developing multilayer Cu2-xS thin film on the glass substrate by physical vapour deposition technique. The results obtained in this method shows that the optimum numbers of layer is 10 ensures formation of crystalline Cu2S structure with optical band gap is around 1.65 eV to 1.85 eV by different characterization technique like XRD, EDX, SEM, Spectrophotometry and PL. The I-V characteristic of Schotkey junction using silver and bulk resistance (ρb) with the sample shows semiconductor behaviour of the same. To the best of our knowledge this is the first time such type of nano-structured Cu2S film fabrication is reported.
关键词： Cu2S,Elemental stacked layer,Absorber layer,Optimization,Physical vapour deposition,Band gap
更新于2025-09-12 10:27:22
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Facile synthesis of tin monosulfide nanosheets via physical vapour deposition and their near-infrared photoresponse
摘要： Two-dimensional layered materials (TDLMs), such as tin sulfide (SnS2), have attracted significant attention due to their vast potential applications in the fields of electronics, optoelectronics, energy conversion, and storage. Tin monosulfide (SnS) is an intrinsic p-type semiconductor in the family of TDLMs. Further explorations of SnS requires the development of efficient synthesis techniques. Here, we report SnS nanosheets grown via a physical vapour deposition (PVD) approach. The morphology was characterized using Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). These SnS nanosheets exhibit a square shape with a smooth surface having an average lateral size of 7 μm and a thickness of 12 nm. No impurities were observed in the SnS nanosheets. Furthermore, photodetectors based on such SnS nanosheets were fabricated. The results show that the as-grown SnS has an excellent photo-response performance for an 850-nm laser with a high responsivity of 1604 AW-1, an external quantum efficiency of 2.34 × 105% and a detectivity of 3.42 × 1011 jones, which are larger than those values reported for previous SnS-based photodetectors. Moreover, the rise and fall times are 7.6 and 29.9 ms, respectively. Our work provides a strategy to obtain high-purity and ultrathin SnS while indicating that SnS has a great potential in applications for near-infrared photodetectors.
关键词： near-infrared photoresponse,tin monosulfide,nanosheets,physical vapour deposition
更新于2025-09-11 14:15:04
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Long-term stable perovskite solar cells with room temperature processed metal oxide carrier transporters
摘要： A hydrophobic electron transporter is introduced to enhance the moisture stability of perovskite solar cells. The device retains 76.8% of the initial efficiency after half a year's storage. Physical vapour deposition that is compatible with flexible substrates is used to fabricate charge transporters. This scheme contributes to achieving stable perovskite devices with low time and energy inputs.
关键词： physical vapour deposition,low-cost,moisture stability,perovskite solar cells,hydrophobic electron transporter
更新于2025-09-11 14:15:04
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Space-confined physical vapour deposition of high quality ZnTe nanosheets for optoelectronic application
摘要： Low-dimensional semiconductor nanomaterials with novel properties hold great promise for potential electronics and photonics applications. Here we report the growth of high quality ultra-thin ZnTe nanosheets by a space-confined physical vapour deposition route. The as-prepared ZnTe nanosheets are well crystallized and exhibit the zinc-blende crystal structure, with lateral dimension up to tens of micrometers and thickness thin to tens of nanometers. P-type conductivity was confirmed by field-effect transistors based on the individual nanosheet. Photodetectors constructed by the high-quality ZnTe nanosheets exhibit high photoresponsivity (453.9 A W?1), excellent stability and reliability. These results reveal that such high-quality ZnTe nanosheets are excellent candidates for optoelectronic applications.
关键词： Space-confined growth,Photodetectors,Electrical properties,Physical vapour deposition,ZnTe nanosheets
更新于2025-09-04 15:30:14