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Improvement of Ga distribution with Sb incorporation for two-step low-temperature processing of CIGSe thin film solar cells
摘要： In this study, the application of Sb incorporation for low-temperature (≤ 450 °C) processing of Cu(In,Ga)Se2 (CIGSe) solar cells is explored. At low reaction temperature, most Ga remains at the back of the ?lm adjacent to the Mo back contact. We observed that the incorporated Sb enhanced grain size and improved device performance compared with similarly processed CIGSe ?lms made without Sb. From the energy-dispersive spectroscopy analysis and secondary ion mass spectrometry results, it was determined that elemental Ga accumulation at the back of the reacted ?lm after the two-step selenization process was signi?cantly alleviated owing to Sb incorporation. Signi?cant Sb-induced grain size enhancement was con?rmed using cross-sectional scanning electron microscopy. The electronic and optical properties of the Sb incorporated CIGSe ?lms were examined with admittance spectroscopy and ?uorescence lifetime imaging techniques.
关键词： Ga distribution,Thin ?lm solar cell,Sb incorporation,Low temperature process
更新于2025-11-14 17:28:48
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[Micro/Nano Technologies] Micro Electro Mechanical Systems Volume 2 || Micro Thermal Flow Sensor
摘要： Measurement of ?uid mechanics is very important in various ?elds, and ?ow sensors have been widely applied to execute accurate and ef?cient measurements. Compared with other sensing principle, thermal ?ow sensors are based on convective heat transfer and take merits of simple structure and easy use and thus offer a practical solution for various ?uidics applications. In this chapter, we describe mainly hot-?lm anemometer fabricated on polyimide substrate. Hot-?lm or hot-wire anemometer utilizes a thermal element that serves as both a joule heater and a temperature sensor. We introduce the principle of thermal ?ow sensing, design and fabrication of the micro hot-?lm ?ow sensor, the measurement methodology, and application cases by using the micro hot-?lm ?ow sensors.
关键词： Flow sensor,Temperature compensation,Micro anemometer,Hot ?lm,Measurement principle
更新于2025-09-23 15:23:52
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Light-illumination stability of amorphous InGaZnO thin film transistors in oxygen and moisture ambience
摘要： The light-illumination stability of amorphous InGaZnO Thin Film Transistors (a-IGZO TFTs) in oxygen and moisture ambience was in-depth characterized by both current-voltage (I-V) and capacitance-voltage (C-V) measurements. With the illuminated light wavelength decreasing, both I-V and C-V curves shifted negatively. When the ambient oxygen content or moisture level increased, the a-IGZO TFTs exhibited more stable properties under light illumination. A qualitative model was proposed to explain the related physical mechanism. The higher oxygen content or moisture level bene?ted the light-illumination-induced oxygen adsorption at back channels of a-IGZO TFTs and prevented the formation of oxygen vacancies (VO) in channel layers; the VO variation with the light illumination became more di?cult and hence led to better light-illumination stability of the corresponding TFT devices.
关键词： Thin ?lm transistor,Light-illumination stability,Amorphous InGaZnO,Ambient gases
更新于2025-09-23 15:23:52
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A Simple Route in Fabricating Carbon-Modified Titania Films with Glucose and Their Visible-Light-Responsive Photocatalytic Activity
摘要： Carbon-modi?ed titania (C–TiO2) ?lms were easily prepared by using an impregnation process with a glucose-containing TiO2 sol. Through controlling calcination conditions, the as-obtained C–TiO2 products exhibited highly photocatalytic activity for the degradation of gaseous NOx under visible light and ultraviolet illumination. The effects of carbon content and calcination temperature on the photocatalytic performances and their photochemical and physical properties were investigated. Carbonaceous species on the TiO2 surface enhanced the visible-light absorption of TiO2 ?lms; however, an excessive amount of carbon on the TiO2 surface reduced its photocatalytic ability due to the serious coverage effect on active sites. The results show that a suitable glucose addition is about 50–100% of the weight of TiO2 content and the optimized calcination temperature is 300 ?C, which leads to better photocatalytic activity under ultraviolet and visible- light irradiations. Accordingly, the simple-prepared C–TiO2 ?lms functioned as visible-light-responsive catalysts, allowing for a feasible producing route for real applications.
关键词： glucose,titania ?lm,impregnation,carbon-modi?ed,visible-light-responsive
更新于2025-09-23 15:22:29
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CVD diamond film detectors for α particles with a new electrode structure of reduced graphene oxide/Au
摘要： (111)-oriented poly-crystalline diamond ?lms (PCDs) have been deposited on Si substrates by MPCVD technology. The new electrode structure of reduced graphene oxide (RGO)/Au was successfully fabricated onto PCDs. Using the circular transmission line model (CTLM), the contact resistance of 6.6 Ω cm?2 was obtained for RGO/Au electrode on PCD surface, which was notably lower than that of 97.4 Ω cm?2 for Ti/Pt/Au electrode. Furthermore, two detectors with these two type electrodes were made respectively. The dark current, photocurrent and energy resolution of these two detectors under 5.5 MeV α particles irradiation from a 241Am source were observed. The results demonstrated that the fabrication of RGO/Au electrode onto PCD can realize a ?ne ohmic contact. The photocurrent of 58.7 nA for the detector with RGO/Au electrode had higher values than that of 8.8 nA for the detector with Ti/Pt/Au electrode at the bias voltage of 100 V respectively. Due to the realization of good contact on PCD surface with RGO/Au electrode, the energy resolution of 11.9% for the detector with RGO/Au electrode better than that of 24% for the detector with Ti/Pt/Au electrode can be obtained. Fabrication of the RGO/Au electrode on PCD may provide a feasible way to improve its detection performance under α particles irradiation.
关键词： α particle irradiation,Diamond ?lm,Ohmic contact,RGO/Au electrode,Raman spectroscopy
更新于2025-09-23 15:22:29
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Effect of temperature fields on optical properties of La <sub/>2</sub> Ti <sub/>2</sub> O <sub/>7</sub> thin films
摘要： In order to study the effect of temperature ?elds on the microstructure, optical properties and response to laser damage of La2Ti2O7 ?lms, a group of ?lms were prepared by electron beam evaporation using the same parameters on Si and fused silica substrates. Then, rapid thermal annealing at different temperatures was applied to simulate the application of a temperature ?eld. The structure, optical constants and response to laser damage of La2Ti2O7 ?lms were investigated by XPS, XRD, ellipsometry and laser damage testing. The results showed that Ti4+ is gradually converted to Ti3+ with increasing temperature resulting in a higher refractive index, larger extinction coef?cient and more serious absorption. When the temperature was higher than 800 °C, the loss of oxygen was more pronounced. The density of annealed ?lms ?rst increased and then decreased when the temperature rises from 600 to 1000 °C, and reached its maximum at 800 °C. And the crystallization, oxygen loss and densi?cation were found to be related to the laser damage threshold of La2Ti2O7 ?lm. The laser damage threshold of the ?lm decreased sharply when the temperature is above 900 °C.
关键词： temperature ?eld,optical properties,La2Ti2O7 ?lm,laser-induced damage
更新于2025-09-23 15:21:21
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - 50mW Average Power Gas-Plasma THz Generation Driven by a Fiber Laser
摘要： Amorphous indium–gallium–zinc oxide (a-IGZO) thin-?lm transistor nonvolatile memory devices with an IGZO charge storage layer were evaluated for the ?rst time for multi-level cell memory applications. The pristine device was de?ned as the original state (OS), which can be switched to the programmed state (PS) after a positive gate voltage pulse (for example, 12 V for 10 ms), and to the erased state (ES) after a negative gate voltage pulse (for example, ?15 V for 10 ms). The writing mechanism was attributed to Fowler–Nordheim tunneling of electrons from the channel to the charge storage layer under a positive gate bias and inverse tunneling under a negative gate bias. The devices demonstrated superior electrical programmable and erasable characteristics. A memory window of 2.4 V between OS and PS was maintained after 100 programming/erasing cycles, and a memory window of 2.66 V between OS and ES as well. The memory windows relative to OS are equal to 1.91 and 1.30 V for PS and ES, respectively, for a retention time of 105 s.
关键词： nonvolatile memory,thin-?lm transistor,multi-level cell,In-Ga-Zn-O
更新于2025-09-23 15:21:01
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Minimizing Defect States in Lead Halide Perovskite Solar Cell Materials
摘要： In order to reach the theoretical e?ciency limits of lead-based metal halide perovskite solar cells, the voltage should be enhanced because it su?ers from non-radiative recombination. Perovskite materials contain intrinsic defects that can act as Shockley–Read–Hall recombination centers. Several experimental and computational studies have characterized such defect states within the band gap. We give a systematic overview of compositional engineering by distinguishing the di?erent defect-reducing mechanisms. Doping e?ects are divided into in?uences on: (1) crystallization; (2) lattice properties. Incorporation of dopant in?uences the lattice properties by: (a) lattice strain relaxation; (b) chemical bonding enhancement; (c) band gap tuning. The intrinsic lattice strain in undoped perovskite was shown to induce vacancy formation. The incorporation of smaller ions, such as Cl, F and Cd, increases the energy for vacancy formation. Zn doping is reported to induce strain relaxation but also to enhance the chemical bonding. The combination of computational studies using (DFT) calculations quantifying and qualifying the defect-reducing propensities of di?erent dopants with experimental studies is essential for a deeper understanding and unraveling insights, such as the dynamics of iodine vacancies and the photochemistry of the iodine interstitials, and can eventually lead to a more rational approach in the search for optimal photovoltaic materials.
关键词： semiconductor,solar energy,photovoltaics,doping,thin ?lm materials,voltage loss,stabilization,optimization,charge generation,light harvesting
更新于2025-09-23 15:21:01
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Compact and Low-Profile UWB Antenna Based on Graphene-Assembled Films for Wearable Applications
摘要： In this article, a graphene-assembled ?lm (GAF)-based compact and low-pro?le ultra-wide bandwidth (UWB) antenna is presented and tested for wearable applications. The highly conductive GAFs (~106 S/m) together with the ?exible ceramic substrate ensure the ?exibility and robustness of the antenna, which are two main challenges in designing wearable antennas. Two H-shaped slots are introduced on a coplanar-waveguide (CPW) feeding structure to adjust the current distribution and thus improve the antenna bandwidth. The compact GAF antenna with dimensions of 32 × 52 × 0.28 mm3 provides an impedance bandwidth of 60% (4.3–8.0 GHz) in simulation. The UWB characteristics are further con?rmed by on-body measurements and show a bending insensitive bandwidth of ~67% (4.1–8.0 GHz), with the maximum gain at 7.45 GHz being 3.9 dBi and 4.1 dBi in its ?at state and bent state, respectively. Our results suggest that the proposed antenna functions properly in close proximity to a human body and can sustain repetitive bending, which make it well suited for applications in wearable devices.
关键词： wearable antenna,UWB,CPW,graphene-assembled ?lm
更新于2025-09-23 15:21:01
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Strongly Enhancing Photocatalytic Activity of TiO2 Thin Films by Multi-Heterojunction Technique
摘要： The photocatalysts of immobilized TiO2 ?lm suffer from high carrier recombination loss when compared to its powder form. Although the TiO2 with rutile-anatase mixed phases has higher carrier separation ef?ciency than those with pure anatase or rutile phase, the single junction of anatase/rutile cannot avoid the recombination of separated carriers at the interface. In this study, we propose a TiO2/SnO2/Ni multi-heterojunction structure which incorporates both Schottky contact and staggered band alignment to reduce the carrier recombination loss. The low carrier recombination rate of TiO2 ?lm in TiO2/SnO2/Ni multi-heterojunction structure was veri?ed by its low photoluminescence intensity. The faster degradation of methylene blue for TiO2/SnO2/Ni multi-junctions than for the other fabricated structures, which means that the TiO2 ?lms grown on the SnO2/Ni/Ti coated glass have a much higher photocatalytic activity than those grown on the blank glass, SnO2-coated and Ni/Ti-coated glasses, demonstrated its higher performance of photogenerated carrier separation.
关键词： titanium dioxide,multijunction,thin ?lm,photocatalysis,functional coatings
更新于2025-09-23 15:21:01