Structural, Optical and Electrical Properties of Evaporated CdSe Films

CdSe films are of great interest for use in thin film photoelectric devices. A simple chemical precipitation method is adopted for the first time to synthesise CdSe powder. Films on glass obtained at different substrate temperatures TS such as 300, 373, 423 and 473 K have been characterised by X-ray diffraction, optical absorption and Hall measurements.

Evaporated Thin Films of CdS and CdTe: Optimization for Photovoltaic Applications

Thin films of cadmium sulphide and cadmium telluride have been prepared by thermal evaporation under various conditions of deposition. These films have been characterized optically. electrically and for structure determination. The results of these characterizations along with the initial results of all thin film CdS/CdTe solar cells are presented in this paper

Influence of the Source to Substrate Distance on the Growth,Tribological Properties and Optical Properties of Be Films

The Be films were prepared by thermal evaporation at different sources to substrate distances（SSD） on glass substrates. The decrease of SSD from 90 mm to 50 mm caused the increase of substrate temperature and the rising density of incident Be atoms, thus the properties of Be films greatly changed accordingly. The experimental results showed that the grain diameter in the Be films transited from below 100 nm to 300 nm, the film growth rate increased from 2.35 nm/min to 4.73 nm/min and the roughness increased from 7 nm to 49 nm. The performance study suggested that the friction coefficient of Be films increased from 0.13 to 0.27 and was related to the surface roughness and inner structure, the near-infrared reflectance of Be films increased from 40% to 85% with the increase of wavelength and concurrently decreased with the decrease of SSD, respectively. The performance study indicated that the Be film had the potential application in specific near-infrared reflectance optical system.

Self-pumping ultra-thin film evaporation on CNT-embedded silicon nitride nanopore membrane

The development of nanoporous membrane structure provides a potential opportunity for the advanced ultra-thin liquid film evaporation process,for which the ability of effectively and continuously maintaining the nano-thin liquid film is crucial to realize its superior performance.In this work,we elucidated the nanopore-based ultra-thin water film evaporation characteristics with non-equilibrium molecular dynamics simulation.A self-pumping water transport through the nanopore was observed,which is attributed to the driving force induced by the evaporation meniscus of thin liquid film.The dry-out crisis will occur with the increasing membrane thickness.We demonstrated that the hydrophobic carbon nanotube(CNT)can be utilized as the coating inside the hydrophilic silicon nitride(Si_(3)N_(4))nanopore,which reduces the flow resistance and presents an excellent capability to replenish the evaporated water.Based on the above findings,the internal coating of CNT is an advisable strategy for nanopore-based ultra-thin liquid film evaporation,possessing a stable high evaporation flux as well as a good mechanical strength.

The effect of interfacial evaporation on heat and mass transfer of falling liquid film

Analysis of experimental data and estimation of the order of magnitude for interfacial mass diffusion have demonstrated that considerable excess evaporation exists on the free interface of falling liquid film, and that the capillary pressure caused by surface tension is the driving force of this excess interfacial evaporation, which we called the “capillarity-induced interfacial evaporation”. By correlating the experimental data, an empirical expression of the effective capillary radius, r\-e, is obtained with which the evaporative rate formula we derived and reported previously has been modified to improve the prediction of the critical heat flux for film breakdown. Comparisons with the available predicting models show that our modified equation can predict the experimental results with much lower relative deviation.

Improved film evaporator for mechanistic understanding of microwave-induced separation process

Microwave-induced film evaporation separation process has been reported recently to separate the polar/nonpolar mixture.However,the efficiency of the separation is still too low for practical applications,which requires further enhancement via different strategies such as optimization design of evaporator structure.In addition the depth understanding of the separation mechanisms is great importance for better utilization of the microwaveinduced separation process.To carry out these investigations,a novel microwave-induced falling film evaporation instrument was developed in this paper.The improvement of the enhancement effect of microwave-induced separation was observed based on the improved film evaporator.The systematic experiments on microwave-induced separation with different binary azeotropic mixtures(ethanol-ethyl acetate system and dimethyl carbonate(DMC)-H20 system)were conducted based on the new evaporator.For the ethanol-ethyl acetate system,microwave irradiation shifted the direction of evaporation separation at higher ethanol content in the starting liquid mixture.Moreover,for DMC-H20 system microwaveinduced separation process broke through the limitations of the traditional distillation process.The results clearly demonstrated the microwave-induced evaporation separation process could be commendably applied to the separation of binary azeotrope with different dielectric properties.Effects of operating parameters are also investigated to trigger further mechanism understanding on the microwave-induced separation process.

Dynamic simulation and experimental validation of a two-phase closed thermosyphon for geothermal application

The heat transfer perfonmance of a vertical two-phase closed thermosyphon(TPCT)used in a geothermal heat pump was experimentally investigated.The TPCT is a verticalplain steel pipe with inner diameter of 114 mm and bored 368 m deep underground.Carbon dioxide(CO_(2))is used as working fluid.In the TPCT there is no condensation section.CO_(2)is condensed by the evaporator pf the heat pump,flows into the head of the TPCT and nuns down as a falling film along the inner wall of the pipe.For the heat transfer simulation in the TPCT,a quasi-dynamic model in which the mass transfer between the liquid and vapor phases as well as the conduction heat transfer from the surrounding soil towards the pipe is treated dynamically.However the film flow modeling is based on the Nusselt theory of frilm condenssation.The compauison of the experimental data with the numerical simulation is presented and discussed.

Structural, Optical and Electrical Properties of Ga Doped ZnO/Cu grid/Ga Doped ZnO Transparent Electrodes

Ga doped ZnO （OZO）/Cu grid/GZO transparent conductive electrode （TCE） structures were fabricated at room temperature （RT） by using electron beam evaporation （EBE） for the Cu grids and RF magnetron sputtering for the GZO layers. In this work, we investigated the electrical and optical characteristics of GZO/Cu grid/GZO multilayer electrode for thin film solar cells by using evaporated Cu grid and sputtered GZO thin films to enhance the optical transparency without significantly affecting their conductivity. The optical transmittance and sheet resistance of GZO/Cu grid/GZO multilayer are higher than those of GZO/Cu film/GZO multilayer independent of Cu grid separation distance and increase with increasing Cu grid separation distances. The calculation of both transmittance and sheet resistance of GZO/Cu grid] GZO multilayer was based on Cu filling factor correlated with the geometry of Cu grid. The calculated values for the transmittance and sheet resistance of the GZO/Cu grid/GZO multilayer were similar to the experimentally observed ones. The highest figure of merit ФTc is 5.18× 10^-3Ω^-1 for the GZO/Cu grid] GZO multilayer with Cu grid separation distance of 1 mm was obtained, in this case, the transmittance and resistivity were 82.72% and 2.17 × 10 ^-4Ωcm, respectively. The transmittance and resistivity are accentahle for nractical thin film snlar cell annlicatinn~

EFFECT OF VACUUM ON THE CRYSTAL FORM AND MORPHOLOGY OF THE EVAPORATED FILM OF COPPER PHTHALOCYANINE

In a previous paper, we have reported the relationship between the crystallite orientation of the evaporated film of copper phthalacyanine （PcCu） （α-form） and the incident angle of molecular beam at 10-5 torr. In this paper, we shall show some research results about vacuum effects on the crystal forms and the morphology of the evaporat-

Preparation and Characterization of Cu_2ZnSn(S_xSe_(1-x))_4Thin Films by Synchronous Sulfo-Selenization of Single-Source Evaporated Metallic Precursors

Cu2ZnSn（S,Se）4（CZTSSe） thin film was prepared using a simple two-step approach based on the single-source evaporation and synchronous sulfo-selenization.Composition,microstructure,morphology,and properties of the asprepared CZTSSe thin films were investigated.XRD and Raman patterns confirmed the formation of single-phase CZTSSe solid solutions.SEM results showed that the CZTSSe thin film had a uniform morphology and large grains.EDS results revealed the composition of CZTSSe film was Cu：Zn：Sn：S：Se = 23.7：12.6：12.2：37.7：13.8（in at%）,which was in accordance with the stoichiometric Cu2ZnSn（S,Se）4.The optical band gap of CZTSSe thin film evaluated from its UV–Vis spectrum was 1.33 eV.The resistivity,carrier concentration,and mobility were 0.53 X cm,7.9 9 1018cm3,and 7.5 cm2/（Vs）,respectively.

Study on thickness uniformity of Ta_(2)O_(5) film evaporated on the inner-face of a hemispherical substrate

Theoretical analysis and experimental study on the thickness distribution of Ta_(2)O_(5) film evaporated on the inner-face of a hemispherical substrate are demonstrated. It is derived that the value of n/R and L/R influence the film thickness distribution(where R is the radius of the hemisphere, n and L are the horizontal distance and vertical height between the evaporation source and the center of the hemisphere, respectively). The whole hemispherical substrate can be coated when n≤L+R, otherwise there is a "blind area" on the substrate when the substrate is self-rotating. A hemispherical composite substrate with a radius of 200 mm is coated with Ta_(2)O_(5) protective film under a certain configuration, the thickness of Ta_(2)O_(5) film at the edge is 0.372 times the film at the vertex which shows that the evaporation characteristics of Ta_(2)O_(5) tend to be a point source.