- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Growth of InGaN films on hardness-controlled bulk GaN substrates
摘要： We carried out an evaluation of the crystalline quality of bulk GaN substrates and the properties of InGaN ?lms grown on them. The Urbach energy estimated by photothermal de?ection spectroscopy and the tail states near the valence band maximum determined by hard x-ray photoemission spectroscopy were larger for hardness-controlled bulk GaN (hard GaN) than those for conventional bulk GaN (conventional GaN). However, InGaN on hard GaN grows in a step-?ow-like mode, while InGaN grown on conventional GaN exhibits spiral-like growth. The photoluminescence decay at room temperature for InGaN grown on the hard GaN was 470 ps, compared with 50 ps for that grown on the conventional GaN. This can be attributed to the suppression of spiral-like growth due to the resistance to deformation of the hard GaN. These results indicate that substrate hardness is one of the most important factors for III–V nitride growth on the bulk GaN substrate.
关键词： hard x-ray photoemission spectroscopy,photoluminescence,bulk GaN substrates,InGaN films,photothermal de?ection spectroscopy,crystalline quality
更新于2025-09-11 14:15:04
-
AIP Conference Proceedings [AIP Publishing THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Karbala City, Iraq (27–28 March 2019)] THE 7TH INTERNATIONAL CONFERENCE ON APPLIED SCIENCE AND TECHNOLOGY (ICAST 2019) - Structure, morphology and optical properties of thermally evaporated Cu2S thin films annealed at different temperatures
摘要： In the present work the preparation of Cu2S alloy was done throughout mixing the sulphur and copper elements according to the proper atomic weight and then put in an evacuated quartz ampoule which then sealed and heated at 1273 K for five hours and left to cool. Thin films from Cu2S powder thicknesses of ~300nm were prepared by thermal evaporation technique on a glass substrate and under vacuum of 10-5 mbar with rate of deposition 25nm/sec. The prepared thin films subjected to heat treatment at different temperatures(300, 373 , 473 and 573 K)for half an hour. The structures of Cu2S powder and films have been studied by X–ray diffraction technique. The result reveals that the prepared alloy has cubic structure and coincides with slandered cards while the prepared thin films have amorphous structure. The optical measurement shows that the Cu2S films have direct and indirect energy gap energy gap (Eg opt) for allowed transition. The energy gap (Eg opt) increases slightly with the increase annealing temperature and retune to increase with further increases of annealing temperature. The energy gap (Eg opt) increases from 2.55 to 2.6 eV and then decreases. The transmittance and optical constants such as refractive index (n), extinction coefficient (k) and dielectric constant (εr, εi) have been calculated. The optical constants decrease in the first and then return to increase with annealing temperature.
关键词： Cu2S thin films,optical properties,structural morphology,thermal evaporation,annealing temperature
更新于2025-09-11 14:15:04
-
Multi-mode optical coded patterns enabled by upconversion nanoparticles and photonic crystals
摘要： The Al-Zr-ZnO films was deposited on the surface of n-Si (111) by sol-gel method. The results showed that the average grain size of Al-Zr-ZnO films decreases due to ion doping concentration. Based on XPS analysis, the surface defect oxygen of Al-Zr-ZnO films decreases. As for graphene/ Al-Zr-ZnO Schottky contact, barrier height increased and ideality factor decreased with the increasing of Al ion or Zr ion doping, indicating that the rectifying characteristics of graphene/Al-Zr-ZnO Schottky contacts was enhanced due to ion co-doping. It can be explained that oxygen vacancies of Al-Zr-ZnO films decreases due to the ion doping and weakens Fermi level pinning.
关键词： sol-gel method,Ion doping,Al-Zr-ZnO films,electrical properties,graphene
更新于2025-09-11 14:15:04
-
Vacuum-annealed and oxygen plasma treated ellipsometric investigations on molybdenum bronzes and measurements of their thermo optic coefficients and electronic polarizability coefficients
摘要： In this investigation, we have measured the optical constants (n, k) of vacuum evaporated MoO3 thin films and of ZxMoO3 (Z = H+, Li+) bronze thin films being annealed at different temperatures and with different concentrations (x) over the range 298–453 K without and within an oxygen plasma environment using manual ellipsometry. We have also measured mass densities, thermo optic coefficients (TOCs), electronic polarizability coefficients (EPCs) and the coefficients of temperature dependence of density of MoO3 thin film and of its bronzes over the same temperature range. It was found that the change in density and porosity of MoO3 thin film (when annealed at 453 K for 36 h) was not more than 6.4% and 15% respectively from the room temperature data. In the case of bronzes, when the samples H0.203MoO3, Li0.076MoO3 and Li0.133MoO3 were annealed at 453 K within an oxygen plasma over different periods of times, it was found that the overall increase in mass density and decrease in the porosity was not more than 4% and 11%, respectively from the initial data at room temperature. Comparably, when the samples H0.211MoO3 and Li0.27MoO3 were annealed at 453 K within an oxygen plasma over different periods of time, the respective decrease in density and increase in porosity was found not more than 3.4% and 6% from the room temperature data. All these results are mostly due to evolution of H2O which causes diffusion of oxygen leading to shallow and deep localised states in the oxide bronze layers. TOCs and EPCs of samples HxMoO3 (x = 0.203) and LixMoO3(x = 0.076, 0.133) upon annealing at 453 K (without and within an oxygen plasma) over different periods of times have an increase in TOCs and in EPCs, and that increase is from 0.10 × 10?4 K?1 to 13.5 × 10?4 K?1 and 0.13 × 10?27 cm3 K?1 to 3.2 × 10?27 cm3 K?1, respectively. On the other hand, the thermo optic coefficient and the coefficient of temperature dependence of density of MoO3 thin films decrease from ? 1.2 × 10?4 K?1 to ? 8.86 × 10?4 K?1 and ? 1.86 × 10?4 g cm?3 K?1 to ? 15.13 × 10?4 g cm?3 K?1, respectively. In the case of H0.211MoO3 and Li0.27MoO3 when annealed at 453 K over different periods of time within oxygen plasma, the overall decrease in TOC is from ? 0.3 × 10?4 K?1 to ? 4.62 × 10?4 K?1, and the decrease in coefficient of temperature dependence of density is from ? 0.45 × 10?4 g cm?3 K?1 to ? 8.9 × 10?4 g cm?3 K?1. These results are due to linear thermal expansion effect.
关键词： ellipsometry,thermo optic coefficients,electronic polarizability coefficients,MoO3 thin films,molybdenum bronzes
更新于2025-09-11 14:15:04
-
Systematic Comparison of Thermal Annealing and Laser Treatment of TiO2 Thin Films Prepared by Sol-Gel Processing
摘要： Thin films with titania composition were prepared on glass substrates by dip-coating from coating solutions based on soluble precursor powders. The as-dried deposits were thermally annealed in a furnace and irradiated by a CO2 laser, respectively. Oven temperature can systematically be correlated to laser power density in terms of film thickness and refractive index. Results indicate that the formation of anatase and rutile critically depends on the different treatment conditions. Some specific microstructural features that originate from the laser irradiation are highlighted.
关键词： Laser annealing,Sol-gel processing,Thermal curing,Thin films,TiO2
更新于2025-09-11 14:15:04
-
Effect of the Substrate Temperature on the Properties of SnO<sub>2</sub> Thin Films Prepared by Ultrasonic Spray for Solar Cells Applications
摘要： Structural, optical properties of SnO2 thin films deposited by spray ultrasonic technique were investigated by varying substrate temperature. The structural characterization of the films was analyzed via X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). These studies indicated that the layers were polycrystalline. Films surface morphologies were studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optical absorption spectrum was recorded using the UV-VIS-NIR spectroscopy and the films were found to be transparent. The optical transmittance varied with substrate temperature from 60–80% over a wide range of wavelength. Optical measurements showed that the layers had a relatively high absorption coefficient of 105 cm?1. A shift in the absorption edge was observed and the films exhibited direct transitions with band gap energies ranging from 3.85 to 3.94 eV.
关键词： transparent and conductive tin dioxide,SnO2 thin films,spray ultrasonic technique,substrate temperature
更新于2025-09-11 14:15:04
-
Effect of carbon quantum dots on the optical and electrical properties of polyvinylidene fluoride polymer for optoelectronic applications
摘要： In this work, the effect of carbon quantum dots (CQDs) on the optical and electrical properties of polyvinylidene fluoride (PVDF) has been investigated. Different weight percent (0, 1, 3, 5 and 10 wt%) ratios of CQDs/PVDF nanocomposite films were prepared using solution casting technique. The morphological properties of CQDs were examined using a transmission electron microscope (TEM). The optical properties of the prepared plain PVDF and CQDs/PVDF nanocomposite films were measured using UV–Visible spectrophotometer in the wavelength range 190–1200 nm. The direct energy band gap (Eg dir.) of the prepared films decreases from 5.28 to 2.96 eV as the wt% ratio of CQDs/PVDF increases from 0 to 10.0%. The DC electrical conductivity (σDC) of the prepared nanocomposite films are measured in the temperature range from 298 to 398 K. The electrical conductivity of the nanocomposite films has been enhanced six times in magnitude as compared with that of the plain PVDF film, as the wt% ratio of CQDs/PVDF increases up to 10 wt%. The enhancement in the optical and electrical properties of PVDF makes it as a novel candidate in various optoelectronic applications.
关键词： Optical properties,Electrical properties,Polyvinylidene fluoride,Nanocomposite films,Carbon quantum dots
更新于2025-09-11 14:15:04
-
[Frontiers of Nanoscience] Nanostructured Thin Films Volume 14 || Spectroscopic and electrical properties of hybrid thin films for solar cell applications
摘要： Third-generation solar cells are designed in order to be able to fabricate thin film solar cells with solution deposition techniques and to obtain high-efficiency solar cells. There are two types of well-known solution-phase-fabricated solar cells: (1) multilayer structure and (2) bulk heterojunction (BHJ) solar cells. Multilayer structure solar cells are fabricated layer by layer of semiconductors, whereas BHJ solar cells consist of two semiconducting materials mixed in one common solvent and deposited onto a conductive glass substrate. Compared with multilayer structures, the BHJ method enables a reduction of the electron pathways between the two materials. One type of solution process for BHJ solar cells is the polymer-nanocrystal BHJ (or hybrid) solar cell. Hybrid BHJ solar cells are fabricated by blending the conducting polymer and inorganic colloidal NCs, and thus combining the properties of both organic and inorganic nanocrystals semiconductors. In this process, the performance of hybrid BHJ solar cells is influenced by the nanocrystals’ shape, solubility, and surface modification, as these properties are believed to affect the crystals’ incorporation in the polymer matrix.
关键词： bulk heterojunction,charge transport,ligand exchange,solar cells,nanocrystals,thin films,polymer
更新于2025-09-11 14:15:04
-
Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides
摘要： Magnetic binary oxides with the rocksalt structure constitute an important class of materials for potential applications as electronic or electrochemical devices. Moreover, they often become a theoretical playground, due to the simple electronic and crystal structures, in the quest for novel phenomena. For these possibilities to be realized, a necessary prerequisite would be to grow atomically ordered and controllably-strained binary oxides on proper substrates. Here we systematically explore the use of pulsed laser deposition technique (PLD) to grow three basic oxides that have rocksalt structure but different chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable) and EuO (unstable). By tuning laser fluence FL, an epitaxial single-phase NiO thin-film growth can be achieved in a wide range of growth temperatures 10 ≤ TG ≤750 °C. At the lowest TG, the out-of-plane strain raises to 1.5%, which is five times higher than in NiO film grown at 750 °C. MnO thin films that had long-range order were successfully deposited on the MgO substrates after appropriate tuning of deposition parameters. The growth of MnO phase was strongly influenced by FL and the TG. EuO films with satisfactory quality were deposited by PLD after oxygen availability had been minimized. Synthesis of EuO thin films at rather low TG = 350 °C prevented thermally-driven lattice relaxation and allowed growth of strained films. Overall, PLD was a quick and reliable method to grow binary oxides with rocksalt structure in high quality that can satisfy requirements for applications and for basic research.
关键词： Thin films,Nickel monoxide,Long-range ordered,Manganese monoxide,Europium monoxide,Strain engineering
更新于2025-09-11 14:15:04
-
[IEEE 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Lviv, Ukraine (2019.7.2-2019.7.6)] 2019 IEEE 2nd Ukraine Conference on Electrical and Computer Engineering (UKRCON) - Dependence of the Thin Film Solar Cells Efficiency from Operating Temperature
摘要： The made research results of the dependence of the film photovoltaic converters efficiency on their operating temperature and their comparison are considered in the paper. The physical mechanisms of temperature influence analysis on output, diode and electronic parameters of photovoltaic converters was conducted. The efficiency temperature coefficients of the photovoltaic converter, which make up for devices with a CdTe of -0.14 rel.%/C, CuInSe -0.36 rel.%/C, amorphous silicon -0.21 rel.%/C were obtained. The analytical processing and analysis of the light diode characteristic effect on the PVC efficiency based on the CdTe showed that the temperature stability of their efficiency is ensured by the diode current density, the incision which increases by 50% from 1.9·10-9 A to 2.7·10-9 A with the temperature rise from 20°С to 50°С.
关键词： solar cells,thin films,output and diode parameters,working temperature,photovoltaic converters,efficiency
更新于2025-09-11 14:15:04