Source Thermal Evaporation Research Articles

Single-source thermal deposition of (BA)2(MA)3Pb4I13 perovskite for a novel SnO2NRs/comp-TiO2@ irradiated-ITO based 2D/3D perovskite solar cell: Comparative study of irradiated ITO layer and its effect on device performance

Perovskite solar cells have achieved very good efficiency but their stability is still a big issue. To achieve an efficient a stable perovskite solar cell; a new simple single source thermal evaporation approach has been used to deposit 2D/3D (BA)2(MA)3Pb4I13 perovskite active layer, for realization of novel architecture of stable perovskite solar cell. Bi ions irradiated ITO electrode, coated with compact TiO2 and SnO2 nano-rods (NRs) layers, has been used as ETL. A unique approach is adopted to deliberately place SnO2 NRs horizontally on the surface comp-TiO2 coated irradiated ITO. Four, SnO2NRs/comp-TiO2@ irradiated-ITO based 2D/3D perovskite devices, have been fabricated with 1.2 GeV Bi ions irradiated ITO, at four different fluences (1.3 × 1011, 6.5 × 1011, 1.3 × 1012 and 2.6 × 1012 ions/cm2). Nano-hillocks formed by irradiation proved to contribute for the better performance to a certain point. It was found that the choice of using horizontally place SnO2-NRs in ETL contributed for better performance and stability of proposed device. Among four fabricated devices highest efficiency of 13.6 % is obtained for ITO irradiated with 1.3 × 1012 ions/cm2 fluence which is very encouraging for 2D/3D hybrid perovskite based solar cells in addition to improved performance all the devices showed good stability.

Antimony sulfide selenide thin film solar cells prepared from thermal evaporation sources produced via chemical reactions

Continued research during the past twenty years has contributed toward an increase in the conversion efficiency of antimony sulfide selenide thin film solar cells above 10%. Hence, new methodologies to open-up this research are relevant. Here, antimony sulfide selenide thin film solar cells were prepared by thermal evaporation from Sb2SxSe3-x sources obtained via an in-situ reaction of SbCl3, Se and Sb2S3 for a desired mole-ratio. A thin film (175 nm) of Sb2S2.1Se0.9 prepared this way with a bandgap (Eg) of 1.67 eV and photoconductivity, 10 −6 Ω– 1 cm– 1. Its solar cell, SnO2:F (FTO)/CdS(100 nm)/Sb2S2.1Se0.9 (175 nm)/C–Ag, has an open circuit voltage (Voc) of 0.514 V, short circuit current density (Jsc) of 11.78 mA cm – 2, and a solar-to-electric energy conversion efficiency (η) of 2.36%. Powder mixture with increased Se-content in the SbCl3 + Se + Sb2S3 mixture was produced in a tubular oven at 450 °C, and used as a source. A thin film of Sb2S0.7Se2.3 (190 nm) produced this way has an Eg of 1.29 eV and photoconductivity, 7x10 – 5 Ω – 1 cm – 1. For its solar cell, FTO/CdS(100 nm)/Sb2S0.7Se2.3 (190 nm)/C–Ag, Voc is 0.455 V; Jsc, 20.3 mA cm – 2 and η, 4.52%. This method of preparing Sb2SxSe3-x thin film solar cells of varying compositions offers versatility in vacuum thermal evaporation from sources prepared from laboratory grade reagents. Perspectives for further work to improve the solar cell efficiency are presented.

Desorption characteristics of selenium and tellurium thin films

The temperature-dependent desorption behavior of selenium and tellurium is investigated using a heated quartz crystal microbalance. Prior to heating the quartz crystal microbalance, selenium and tellurium films with varying thickness were deposited using thermal effusion cells in a molecular beam epitaxy system for subsequent determination of temperature-dependent mass loss of the deposited films. The desorption rate for tellurium was found to exhibit one sharp peak around 190 °C, indicating the loss of the entire film irrespective of film thickness within a temperature window of 20 °C, which was completely evaporated at 200 °C. Similar experiments for selenium revealed that the thermal desorption took place via a two-stage process with a smaller portion of the material desorbing within an even narrower temperature window of 5 °C at a much lower peak temperature of 65 °C, while most selenium desorbed within a temperature range of 10 °C around 90 °C. This two-stage behavior indicated the presence of at least two chemically distinct selenium species or binding states. The direct and quantitative determination of the chalcogen desorption process provides important insights into the kinetics of chalcogenide-based film growth and is in addition of applied benefit to the research community in the area of Se/Te capping and decapping of air sensitive materials as it provides temperature ranges and rates at which full desorption is achieved. Our work furthermore points toward the need for a more detailed understanding of the chemical composition state of atomic and molecular beams supplied from thermal evaporation sources during growth.

Effect of Firing Holding Time on Density, Porosity, and Hardness, Crucible Materials Based on Evaporation Boats

Evaporation boats are conductive advanced ceramic composites with the best thermal evaporation source for metalizing applications. The short life time of the evaporation boats causes the metalizing industry to produce large amounts of evaporation boats waste. However, studies on the utilization of evaporation boat waste are still limited. Therefore, this study aims to determine the effect of firing holding time on the density, porosity, and hardness of crucible materials made from evaporation boats waste. The material used in this research is a mixture of evaporation boats waste powder, kaolin, and graphite, with a composition of 50%, 25% and 25%, respectively. During the mixing process, 15% of the water is added. The compacting process carried out with a compaction pressure of 25 MPa. The firing process is carried out at a temperature of 1000<sup>o</sup>C with holding times of 60, 90, 120, 150, and 180 minutes. The test results show that the holding time of firing has an effect on density, porosity, and hardness. The highest density value was 1,91 g/cm<sup>3</sup> at a holding time of 180 minutes, and the lowest was 1,77 g/cm<sup>3</sup> at a holding time of 60 minutes. The highest porosity value is 4,10% at a holding time of 60 minutes, and the lowest is 2,16% at a holding time of 180 minutes. The highest hardness value was 12,84 HV at a holding time of 180 minutes, and the lowest was 8,3 HV at a holding time of 60 minutes. The longer holding time in the firing process results in a decrease in the porosity content. The decrease in the porosity content results in an increase in density and hardness of the cruicible specimens.

69‐4: Collimating and Recycling Linear Evaporation Source for AMOLED Mass Production

It is important in AMOLED pixel forming process to reduce low angle region flux of particles emitted from thermal evaporation source. Because it can cause the mask shadow effect, nozzle clogging and material waste. We developed Collimating and Recycling source. It has unique nozzle structure that can make low angle flux go down to recycling basket and pass only high angle flux through final nozzle. It can make collimating flux that is similar with cosine to the tenth. And it can recycle material 70%.

Ultrathin 2D ternary Bi2Te2Se flakes for fast-response photodetectors with gate-tunable responsivity

Two-dimensional (2D) ternary materials have sprung up in a broad variety of optoelectronic applications due to their robust degree of freedom to design the physical properties of the materials through adjusting the stoichiometric ratio. However, the controlled growth of high-quality 2D ternary materials with good chemical stoichiometry remains challenging, which severely impedes their further development and future device applications. Herein, we synthesize ternary Bi2Te2Se (BTS) flakes with a thickness down to 4 nm and a lateral dimension about 60 µm by an atmospheric-pressure solid source thermal evaporation method on a mica substrate. The phonon vibration and electrical transportation of 2D BTS are respectively investigated by temperature-dependent Raman spectrum and conductivity measurements. Furthermore, the photodetector based on 2D BTS exhibits excellent performance with a high light on/off ratio of 1300 (365 nm), a wide spectral response range from 365 to 980 nm, and an ultra-fast response speed up to 2 µs. In addition, its electrical and photoelectric properties can be modulated by the gate voltage, offering an improved infrared responsivity to 2.74 A W−1 and an on/off ratio of 2266 under 980 nm. This work introduces an effective approach to obtain 2D BTS flakes and demonstrates their excellent prospects in optoelectroni cs.

Growth of Cu(In,Ga)Se2 thin films by a novel single flash thermal evaporation source

A novel route of a single flash thermal evaporation technique has been used for deposition of Cu(In,Ga)Se2. This route allows the deposition of stoichiometric CIGS layers direct from powder elements without selenization or any treatment. Structure, optical properties and surface morphology of the deposited films at various substrate temperatures have been investigated using X-ray diffraction (XRD) analysis, Raman spectroscopy, photospectroscopy, Scanning electron microscopy (SEM) and Atomic force microscopy. The structure and the optical properties of deposited films depend on the substrate temperatures which play crucial rule on the stoichiometry of the film by changing mainly the content of selenium. Increasing the substrate temperature improved the crystallinity of the films and the best stoichiometric film has been found at 220°C, the grain size increased from 146 to 286 Å, Whereas, the band gap reduced to 1.37 eV.

Molecular flux distribution from the thermal evaporation source using Monte Carlo method: The importance of interparticle collision

Molecular flux distribution is critical information to obtain uniform thin films using the thermal evaporation technique in vacuum. However, the flux distribution is a quite complex function depending on the geometry of evaporation sources and the individual motion of evaporated molecules. This makes it difficult to establish a model describing the flux distribution that is directly associated with the distribution of film thickness on the substrate. In this study, we found that the conventional analytic model severely deviates from the experimental flux distribution except in the simple case. Thus, we developed a numerical model based on the Monte Carlo method to simulate the angular flux distribution from a thermal evaporation source. In particular, interparticle collisions have been handled rigorously. Evaporated molecules were assumed to be point particles that collide with each other and adsorbed (emitted) on (from) the nozzle wall of the source. The interparticle collision probability was addressed with the rarefied gas dynamics and the cosine law of emission was adopted to simulate the adsorption/emission process at the nozzle wall. Finally, we compared the simulated flux distribution with experiments on the cylindrical nozzle with various aspect ratios and deposition rates. The simulation results show excellent agreement with experimental data, indicating that interparticle collision is a key parameter for accurate simulation.

The influence of Ag doping and annealing on phase, structural and carrier transport characteristics of CIS thin films

Abstracts The un-doped and Ag-CIS thin films were deposited on quartz glass substrates by single source thermal evaporation method. Then, some CIS films were annealed in vacuum or N2 atmosphere from 350 °C to 550 °C. The results of XRD patterns showed the phase compositions of CIS thin films were changed with the increase of annealing temperature. Meanwhile, the results of Raman measurement confirmed a dramatic transition from CA phase to CH phase. Furthermore, the Ag atoms could promote the recrystallization process and the transition from CA phase to CH phase, which might result in the improvement of optical-electrical properties of CIS film. The transient photocurrent of the CIS-3 sample annealed at 450 °C was higher than those of other samples, which might be related to the good crystal quality. The results of I-V curves confirmed the N-type conduction of CIS-3 films, which was consistent with the results of EDS measurement. The C-V results of CIS-2 films also were the same as the results of EDS measurement. Furthermore, for the CIS-2 samples, with increase of annealing temperature, the change of conduction type may be related to the S element volatilization under vacuum situation and the decomposition of the substitutional defects AgIn.

Process Development for Thin Film Solid State Battery on Four Inch Wafer Using Glove Box Attached Custom Built Single Chamber PVD System

A process for fabricating thin film solid state battery on four-inch silicon wafer has been developed in a custom built hybrid PVD configuration in a single chamber attached to a glove box. In this work, we have performed six layer deposition, which includes Lithium evaporation in the same chamber. As the cathode current collector, Aluminum of 2-5 microns thick, was deposited using specially designed compact thermal evaporation sources, after aluminium deposition thin layer metallic nickel or cobalt was used as the barrier for Lithium cobalt oxide cathode. The total thickness of the thin film solid state battery is 15-18 micron, with a specific capacity between 50-80 µAh-Cm2. The capacity of the batteries reduced to 20-30 percent from the initial capacity after 100 cycles. Some batteries were cycled up to 15,000 cycles and the capacity fading is about 50-60 percent. Based on different studies, we have established the protocol to make reliable thin film battery processing using custom built PVD system in the laboratory scale. The investigations have shown degradation due to the intrinsic material limitations rather than process induced degradation.

Microstructural and optical properties of HC(NH2)2PbI3 thin films prepared by single source thermal evaporation

The HC(NH2)2PbI3 thin films as the perovskite solar cells absorption layer were prepared by single-source thermal evaporation. The stoichiometric ratio effects of HC(NH2)2I/PbI2 precursors on the properties of HC(NH2)2PbI3 thin films were investigated. The microstructure, surface morphology and optical properties of HC(NH2)2PbI3 thin films were characterized by X-ray diffraction (XRD), energy dispersive spectroscope, scanning electron microscopy and spectrophotometer respectively. The results show that, with stoichiometric ratio of FAI/PbI2 3:1, the XRD results of formamidine lead iodine thin films prepared by single source thermal evaporation indicated the typical peaks of HC(NH2)2PbI3 thin films with few impurities. The dense and uniform films were formed with large crystal grains on the surface and high crystallization. The Pb/I element ratio was approximate to the ideal stoichiometric ratio of HC(NH2)2PbI3 thin films. The band gap of the HC(NH2)2PbI3 thin film calculated was 1.5 eV, which satisfied the optical properties requirement of absorbers for perovskite solar cell applications, making them potential applicable for large-area efficient perovskite solar cells.

Modelling of a vacuum metallization patterning method for organic electronics

The high throughput roll-to-roll patterning of metal thin films could be used to create organic functional devices. In this paper we present research into the compatibility of an in-vacuum selective metallization technique, which uses a sacrificial oil to define the metal electrode pattern for functional devices. The exact mechanism of the sacrificial oil masking, pattern definition and oil vaporization, due to the radiant heating from the thermal evaporation source, is described from previous research and experimental findings. The thermal modelling of this process develops further the requirements for the masking oil. It is found that in this particular system the oil thickness must be 1.63±0.31μm to match the radiative energy, and not be evaporated prior to leaving the metallization zone or to remain, as excess, after metallization is complete. The temperatures required are low and compatible with heat sensitive functional organic materials. The definition of the metal pattern edges is found to be like the liquid oil but thermal modelling still supports the theory of the oil vapor having the largest masking effect and concludes that the pattern definition quality does not depend on the sacrificial oil masking or vaporization effects but on the flexography patterning.

The Effect of Stoichiometry on the Stability of Inorganic Cesium Lead Mixed-Halide Perovskites Solar Cells

Metal halide perovskite solar cells that use the inorganic cation Cs have been shown to have better thermal stability than the organic cation containing counterparts, and CsPbI2Br has a more suitable (lower) band gap than CsPbIBr2 as a photovoltaic energy harvesting material. However, increase in iodine content reduces structural stability due to the preference toward the non-perovskite orthorhombic phase when the film is exposed to air. In this work, the effect of varying stoichiometry of CsPbI2Br perovskite on film quality such as the grain size, presence of impurities and nature of impurity grains, photoluminescence, morphology, and elemental distribution are studied. Details on how to vary the stoichiometry during the dual source thermal evaporation process are reported. It is found that the air stability of CsPbI2Br film correlates with the CsBr-to-PbI2 deposition rate ratio, in which the CsBr-rich CsPbI2Br is the most stable upon air exposure, while the stoichiometrically balanced CsPbI2Br perovskit...

Substrate temperature dependence of structural, morphological and optical properties of Sn4Sb6S13 thin films deposited by vacuum thermal evaporation

In this work, structural and morphological properties of Sn4Sb6S13 thin films grown by single source thermal evaporation were investigated. The films were deposited onto glass substrates heated in the temperature range 30–200°C then characterized by XRD, AFM, SEM and Raman spectroscopy. The films are preferentially oriented along the (6¯11) plane. Analysis of the surface morphology reveals that the films had an average roughness increasing from 2.81 to 8.23nm as the substrate temperature increases from 30 to 200°C. The variations of the microstructural parameters, such as crystallite size (D), dislocation density (δ), the number of crystallites per unit area (N), the stacking fault probability (P) and strain (ε) with substrate temperature were investigated. Raman measurement was used to obtain more information about structural changes of Sn4Sb6S13 films. The optical parameters were deduced by using Forouhi-Bloomer models.

Hole Transport Layer Free Inorganic CsPbIBr2 Perovskite Solar Cell by Dual Source Thermal Evaporation

Hole Transport Layer Free Inorganic CsPbIBr₂ Perovskite Solar Cell by Dual Source Thermal Evaporation

All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

Synthesis and Characterization of HC(NH 2 ) 2 PbI 3 perovskite thin film prepared by single source thermal evaporation

Synthesis and Characterization of HC(NH ₂ ) ₂ PbI ₃ perovskite thin film prepared by single source thermal evaporation

Effects of sulfurization temperature on Cu2ZnSnS4 thin film deposited by single source thermal evaporation method

In this study, the effects of sulfurization temperature on the properties of thermally evaporated Cu2ZnSnS4 (CZTS) thin films were investigated. Molybdenum (Mo) coated soda lime glass (SLG) was used as substrates and stoichiometric CZTS powder (99.95%) was used as the source material. XRD patterns showed that CZTS were formed with preferential orientations of (112) > (220) > (312) for all the investigated films. The intensity of (112) peak is found increasing until a certain temperature indicating that the highest degree of crystallinity is achieved together with secondary phases such as ZnS and SnS. It was confirmed by raman shift at 338 cm−1 from Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM) results showed a trend for surface roughness as well as morphology. From Hall effect measurement, all deposited films exhibited p-type conductivity. From UV–vis spectroscopy measurement, the optical band gap of all the films are found in the range of potential absorbers for CZTS based thin film solar cells.

Programmable solid state atom sources for nanofabrication.

In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ∼1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques.

Impact of interface roughness on the performance of broadband blackbody absorber based on dielectric-metal film multilayers

We report on factors affecting the performance of a broadband, mid-IR absorber based on multiple, alternating dielectric / metal layers. In particular, we investigate the effect of interface roughness. Atomic layer deposition produces both a dramatic suppression of the interface roughness and a significant increase in the optical absorption as compared to devices fabricated using a conventional thermal evaporation source. Absorption characteristics greater than 80% across a 300 K black body spectrum are achieved. We demonstrate a further increase in this absorption via the inclusion of a patterned, porous anti-reflection layer.