Pub Date : 2021-12-30DOI: 10.3897/j.moem.7.4.51073
V. Berdnikov
This work is a brief overview of numerical study results for hydrodynamics and convective heat exchange for the classic Czochralski technique obtained at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. Flow structure evolution has been compared for melts with Prandtl numbers Pr = 0.05, 16, 50 and 2700. The regularities of local and integral convective heat exchange in the crucible/melt/crystal system for thermal gravity, thermocapillary and heat-induced gravity capillary convection have been studied. The calculations have been carried out using the finite and compact difference methods. This work is a continuation of an article: Berdnikov VS (2019) Hydrodynamics and heat exchange of crystal pulling from melts. Part I: Experimental studies of free convection mode. Modern Electronic Materials 5(3): 91–100. https://doi.org/10.3897/j.moem.5.3.46647
{"title":"Hydrodynamics and heat exchange of crystal pulling from melts. Part II: Numerical study of free convection mode","authors":"V. Berdnikov","doi":"10.3897/j.moem.7.4.51073","DOIUrl":"https://doi.org/10.3897/j.moem.7.4.51073","url":null,"abstract":"This work is a brief overview of numerical study results for hydrodynamics and convective heat exchange for the classic Czochralski technique obtained at the Institute of Thermophysics, Siberian Branch of the Russian Academy of Sciences. Flow structure evolution has been compared for melts with Prandtl numbers Pr = 0.05, 16, 50 and 2700. The regularities of local and integral convective heat exchange in the crucible/melt/crystal system for thermal gravity, thermocapillary and heat-induced gravity capillary convection have been studied. The calculations have been carried out using the finite and compact difference methods.\u0000 This work is a continuation of an article: Berdnikov VS (2019) Hydrodynamics and heat exchange of crystal pulling from melts. Part I: Experimental studies of free convection mode. Modern Electronic Materials 5(3): 91–100. https://doi.org/10.3897/j.moem.5.3.46647","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"32 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72589187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-30DOI: 10.3897/j.moem.7.4.80758
N. Kalanda, M. Yarmolich, A. Gurskii, A. Petrov, A. Zhaludkevich, O. Ignatenko, M. Serdechnova
In this work, solid solutions of La0.7Sr0.3Mn0.95Fe0.05O3-δ with different oxygen content were obtained by the solid-phase reactions technique. Based on the investigation of the dynamics of changes in the oxygen index (3 – δ) during heating of the samples, the formation of a stressed state in their grains as a result of annealing was established. This results in a decrease in the mobility of oxygen vacancies during the reduction of cations according to the Mn4+ + e– → Mn3+ scheme and explains the decrease of released oxygen amount with an increase of δ as well as the heating rate of the samples. When studying the magnetic properties of the obtained samples, it was found that the temperature dependence of the magnetization obeys the Curie–Weiss law and as the oxygen defficiency increases, the Curie temperature for solid solutions decreases. It was found that the particles are in a frozen ferromagnetic state when measured in the low-temperature region of the М (Т) dependence in “zero-field mode” at Т ˂ ТВ. The presence of ferromagnetism at Т ˃ ТВ leads to a magnetically ordered state, in which the resulting magnetic moment of the magnetic particle is influenced by thermal fluctuations. When considering the temperature values of the magnetization of lanthanum-strontium manganite samples, it was found that with an increase of temperature in the low-temperature region, magnetic ordering is disturbed due to the excitation of magnons with a quadratic dependence of the energy from the wave vector, the number of which increases in proportion to T3/2. This results in a decrease in the manganite magnetization. The observed temperature dependence of the magnetization measured in the “field-cooling mode” was approximated taking into account the quadratic and non-quadratic dispersion laws of the magnon spectrum.
本文采用固相反应技术制备了不同氧含量的La0.7Sr0.3Mn0.95Fe0.05O3-δ固溶体。通过对样品在加热过程中氧指数(3 - δ)变化的动力学研究，确定了退火后晶粒中形成应力态。这导致了Mn4+ + e -→Mn3+还原阳离子过程中氧空位迁移率的降低，并解释了随着δ的增加和样品升温速率的增加，氧释放量减少的原因。对所得样品的磁性能进行研究，发现磁化强度与温度的关系符合居里-魏斯定律，固溶体的居里温度随着氧缺乏度的增加而降低。在“零场模式”的М (Т)依赖的低温区域(Т: ТВ)测量时，发现这些粒子处于冻结的铁磁状态。在Т ТВ处存在铁磁性，导致磁性有序状态，在这种状态下，磁性粒子的磁矩受到热波动的影响。在考虑镧锶锰矿样品磁化的温度值时，发现随着低温区温度的升高，磁振子的激发使磁有序受到干扰，磁振子的数量与波矢量能量呈二次依赖关系，且磁振子的数量与T3/2成比例增加。这导致了锰矿磁化强度的降低。考虑到磁振子光谱的二次和非二次色散规律，对在“场冷却模式”下测量到的磁化强度的温度依赖性进行了近似。
{"title":"Oxygen nonstoichiometry and magnetic properties of doped manganites La0.7Sr0.3Mn0.95Fe0.05O3-δ","authors":"N. Kalanda, M. Yarmolich, A. Gurskii, A. Petrov, A. Zhaludkevich, O. Ignatenko, M. Serdechnova","doi":"10.3897/j.moem.7.4.80758","DOIUrl":"https://doi.org/10.3897/j.moem.7.4.80758","url":null,"abstract":"In this work, solid solutions of La0.7Sr0.3Mn0.95Fe0.05O3-δ with different oxygen content were obtained by the solid-phase reactions technique. Based on the investigation of the dynamics of changes in the oxygen index (3 – δ) during heating of the samples, the formation of a stressed state in their grains as a result of annealing was established. This results in a decrease in the mobility of oxygen vacancies during the reduction of cations according to the Mn4+ + e– → Mn3+ scheme and explains the decrease of released oxygen amount with an increase of δ as well as the heating rate of the samples. When studying the magnetic properties of the obtained samples, it was found that the temperature dependence of the magnetization obeys the Curie–Weiss law and as the oxygen defficiency increases, the Curie temperature for solid solutions decreases. It was found that the particles are in a frozen ferromagnetic state when measured in the low-temperature region of the М (Т) dependence in “zero-field mode” at Т ˂ ТВ. The presence of ferromagnetism at Т ˃ ТВ leads to a magnetically ordered state, in which the resulting magnetic moment of the magnetic particle is influenced by thermal fluctuations. When considering the temperature values of the magnetization of lanthanum-strontium manganite samples, it was found that with an increase of temperature in the low-temperature region, magnetic ordering is disturbed due to the excitation of magnons with a quadratic dependence of the energy from the wave vector, the number of which increases in proportion to T3/2. This results in a decrease in the manganite magnetization. The observed temperature dependence of the magnetization measured in the “field-cooling mode” was approximated taking into account the quadratic and non-quadratic dispersion laws of the magnon spectrum.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90302586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-10DOI: 10.3390/electronicmat2040039
Yujian Sun, Yongcao Zhang, Yuxin Li, Yilin Li
Luminescent solar concentrators (LSCs) are considered promising in their application as building-integrated photovoltaics (BIPVs). However, they suffer from low performance, especially in large-area devices. One of the key issues is the self-absorption of the luminophores. In this report, we focus on the study of self-absorption in perovskite-based LSCs. Perovskite nanocrystals (NCs) are emerging luminophores for LSCs. Studying the self-absorption of perovskite NCs is beneficial to understanding fundamental photon transport properties in perovskite-based LSCs. We analyzed and quantified self-absorption properties of perovskite NCs in an LSC with the dimensions of 6 in × 6 in × 1/4 in (152.4 mm × 152.4 mm × 6.35 mm) using three approaches (i.e., limited illumination, laser excitation, and regional measurements). The results showed that a significant number of self-absorption events occurred within a distance of 2 in (50.8 mm), and the photo surface escape due to the repeated self-absorption was the dominant energy loss mechanism.
发光太阳能聚光器(LSCs)在建筑集成光伏(bipv)中具有广阔的应用前景。然而，它们的性能较低，特别是在大面积设备中。其中一个关键问题是发光团的自吸收。在本报告中，我们主要研究钙钛矿基LSCs的自吸收。钙钛矿纳米晶体(NCs)是一种新兴的LSCs发光材料。研究钙钛矿NCs的自吸收特性有助于理解钙钛矿LSCs的基本光子输运特性。我们使用三种方法(即有限光照、激光激发和区域测量)分析和量化了尺寸为6英寸× 6英寸× 1/4英寸(152.4 mm × 152.4 mm × 6.35 mm)的LSC中钙钛矿NCs的自吸收特性。结果表明，在2 in (50.8 mm)范围内发生了大量的自吸收事件，由于重复自吸收引起的光表面逃逸是主要的能量损失机制。
{"title":"Self-Absorption Analysis of Perovskite-Based Luminescent Solar Concentrators","authors":"Yujian Sun, Yongcao Zhang, Yuxin Li, Yilin Li","doi":"10.3390/electronicmat2040039","DOIUrl":"https://doi.org/10.3390/electronicmat2040039","url":null,"abstract":"Luminescent solar concentrators (LSCs) are considered promising in their application as building-integrated photovoltaics (BIPVs). However, they suffer from low performance, especially in large-area devices. One of the key issues is the self-absorption of the luminophores. In this report, we focus on the study of self-absorption in perovskite-based LSCs. Perovskite nanocrystals (NCs) are emerging luminophores for LSCs. Studying the self-absorption of perovskite NCs is beneficial to understanding fundamental photon transport properties in perovskite-based LSCs. We analyzed and quantified self-absorption properties of perovskite NCs in an LSC with the dimensions of 6 in × 6 in × 1/4 in (152.4 mm × 152.4 mm × 6.35 mm) using three approaches (i.e., limited illumination, laser excitation, and regional measurements). The results showed that a significant number of self-absorption events occurred within a distance of 2 in (50.8 mm), and the photo surface escape due to the repeated self-absorption was the dominant energy loss mechanism.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78369615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-12-01DOI: 10.3390/electronicmat2040038
Atsushi Nitta, Naohiko Chosa, K. Takeda
Recently, active research has been conducted on the development of flexible electronic devices. Hence, the transparent conductive film (TCF), an essential component of the device, must also be flexible. However, the commonly used indium tin oxide (ITO) TCF lacks flexibility and contains rare metal, making resource depletion an issue. Therefore, we focused on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS), which has high flexibility and conductivity. Flexible TCFs have been fabricated by coating PEDOT:PSS on polyethylene naphthalate substrates using an inkjet printer. However, the current issue in such fabrication is the effect of the interface state on the transparency and conductivity of the thin film. In this study, we investigated the effect of surfactant in addition to polar solvents on the properties of thin films fabricated with PEDOT:PSS ink. Although the electrical conductivity was reduced, the transmittance remained above 90%. Thus, these results are comparable to those of ITO TCFs for practical use in terms of optical properties.
{"title":"Effect of Surfactant Addition on Organic Transparent Conductive Films Fabricated by Inkjet Printing Method","authors":"Atsushi Nitta, Naohiko Chosa, K. Takeda","doi":"10.3390/electronicmat2040038","DOIUrl":"https://doi.org/10.3390/electronicmat2040038","url":null,"abstract":"Recently, active research has been conducted on the development of flexible electronic devices. Hence, the transparent conductive film (TCF), an essential component of the device, must also be flexible. However, the commonly used indium tin oxide (ITO) TCF lacks flexibility and contains rare metal, making resource depletion an issue. Therefore, we focused on poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS), which has high flexibility and conductivity. Flexible TCFs have been fabricated by coating PEDOT:PSS on polyethylene naphthalate substrates using an inkjet printer. However, the current issue in such fabrication is the effect of the interface state on the transparency and conductivity of the thin film. In this study, we investigated the effect of surfactant in addition to polar solvents on the properties of thin films fabricated with PEDOT:PSS ink. Although the electrical conductivity was reduced, the transmittance remained above 90%. Thus, these results are comparable to those of ITO TCFs for practical use in terms of optical properties.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76570260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-03DOI: 10.3390/electronicmat2040037
P. Andersson Ersman, Jessica Åhlin, David Westerberg, A. Sawatdee, Patrik Arvén, M. Ludvigsson
Batteryless hybrid printed electronic systems manufactured on glass substrates are reported. The electronic system contains a sensor capable of detecting water, an electrochromic display, conductors, a silicon chip providing the power supply through energy harvesting of electromagnetic radiation, and a silicon-based microcontroller responsible for monitoring the sensor status and the subsequent update of the corresponding display segment. The silicon-based components were assembled on the glass substrate by using a pick and place equipment, while the remainder of the system was manufactured by screen printing. Many printed electronic components, often relying on organic materials, are sensitive to variations in environmental conditions, and the reported system paves the way for the creation of electronic sensor platforms on glass substrates for utilization in see-through applications in harsh conditions. Additionally, this generic hybrid printed electronic sensor system also demonstrates the ability to enable autonomous operation through energy harvesting in future smart window applications.
{"title":"Batteryless Electronic System Printed on Glass Substrate","authors":"P. Andersson Ersman, Jessica Åhlin, David Westerberg, A. Sawatdee, Patrik Arvén, M. Ludvigsson","doi":"10.3390/electronicmat2040037","DOIUrl":"https://doi.org/10.3390/electronicmat2040037","url":null,"abstract":"Batteryless hybrid printed electronic systems manufactured on glass substrates are reported. The electronic system contains a sensor capable of detecting water, an electrochromic display, conductors, a silicon chip providing the power supply through energy harvesting of electromagnetic radiation, and a silicon-based microcontroller responsible for monitoring the sensor status and the subsequent update of the corresponding display segment. The silicon-based components were assembled on the glass substrate by using a pick and place equipment, while the remainder of the system was manufactured by screen printing. Many printed electronic components, often relying on organic materials, are sensitive to variations in environmental conditions, and the reported system paves the way for the creation of electronic sensor platforms on glass substrates for utilization in see-through applications in harsh conditions. Additionally, this generic hybrid printed electronic sensor system also demonstrates the ability to enable autonomous operation through energy harvesting in future smart window applications.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86572338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-02DOI: 10.3390/electronicmat2040036
N. Sidorenko, Yaakov B. Unigovski, Z. Dashevsky, R. Shneck
A unique method was developed to significantly improve the strength of Bi(1−x)Sbx single crystals, the most effective thermoelectric (TE) materials in the temperature range from 100 to 200 K due to their plastic deformation by extrusion. After plastic deformation at room temperature under all-round hydrostatic compression in a liquid medium, n-type Bi–Sb polycrystalline solid solutions show a significant increase in mechanical strength compared to Bi–Sb single crystals in the temperature range from 300 to 80 K. The significantly higher strength of extruded alloys in comparison with Bi–Sb single crystals is associated with the development of numerous grains with a high boundary surface as well as structural defects, such as dislocations, that accumulate at grain boundaries. Significant stability of the structure of extruded samples is achieved due to the uniformity of crystal plastic deformation under all-round hydrostatic compression and the formation of the polycrystalline structure consisting of grains with the orientation of the main crystallographic directions close to the original single crystal. The strengthening of Bi–Sb single crystals after plastic deformation allows for the first time to create workable TE devices that cannot be created on the basis of single crystals that have excellent TE properties, but low strength.
{"title":"A Novel Method to Significantly Improve the Mechanical Properties of n-Type Bi(1−x)Sbx Thermoelectrics Due to Plastic Deformation","authors":"N. Sidorenko, Yaakov B. Unigovski, Z. Dashevsky, R. Shneck","doi":"10.3390/electronicmat2040036","DOIUrl":"https://doi.org/10.3390/electronicmat2040036","url":null,"abstract":"A unique method was developed to significantly improve the strength of Bi(1−x)Sbx single crystals, the most effective thermoelectric (TE) materials in the temperature range from 100 to 200 K due to their plastic deformation by extrusion. After plastic deformation at room temperature under all-round hydrostatic compression in a liquid medium, n-type Bi–Sb polycrystalline solid solutions show a significant increase in mechanical strength compared to Bi–Sb single crystals in the temperature range from 300 to 80 K. The significantly higher strength of extruded alloys in comparison with Bi–Sb single crystals is associated with the development of numerous grains with a high boundary surface as well as structural defects, such as dislocations, that accumulate at grain boundaries. Significant stability of the structure of extruded samples is achieved due to the uniformity of crystal plastic deformation under all-round hydrostatic compression and the formation of the polycrystalline structure consisting of grains with the orientation of the main crystallographic directions close to the original single crystal. The strengthening of Bi–Sb single crystals after plastic deformation allows for the first time to create workable TE devices that cannot be created on the basis of single crystals that have excellent TE properties, but low strength.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"411 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75190124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-11-01DOI: 10.3390/electronicmat2040035
D. Fritsch
The p-type semiconductors Cu2O and ZnRh2O4 have been under investigation for potential applications as transparent conducting oxides. Here, we re-evaluate their structural, electronic, and optical properties by means of first-principles calculations employing density functional theory and a recently introduced self-consistent hybrid functional approach. Therein, the predefined fraction α of Hartree–Fock exact exchange is determined self-consistently via the inverse of the dielectric constant ε∞. The structural, electronic, and optical properties will be discussed alongside experimental results, with a focus on possible technological applications.
{"title":"Structural, Electronic, and Optical Properties of p-Type Semiconductors Cu2O and ZnRh2O4: A Self-Consistent Hybrid Functional Investigation","authors":"D. Fritsch","doi":"10.3390/electronicmat2040035","DOIUrl":"https://doi.org/10.3390/electronicmat2040035","url":null,"abstract":"The p-type semiconductors Cu2O and ZnRh2O4 have been under investigation for potential applications as transparent conducting oxides. Here, we re-evaluate their structural, electronic, and optical properties by means of first-principles calculations employing density functional theory and a recently introduced self-consistent hybrid functional approach. Therein, the predefined fraction α of Hartree–Fock exact exchange is determined self-consistently via the inverse of the dielectric constant ε∞. The structural, electronic, and optical properties will be discussed alongside experimental results, with a focus on possible technological applications.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82172071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-29DOI: 10.20944/preprints202110.0449.v1
A. Molak, A. Szeremeta, J. Koperski
This work shows a correlation between light reflectance, absorption, and morphologies of series of (1-x) BM–x PT, (x = 0.0, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24) ceramics composite. The (1-x) BM–x PT showed features of a black mirror with a low optical energy gap. The measured Vis-NIR diffused reflectance enabled the calculation of the energy gap using the modified Kubelka-Munk function. The estimated energy gap was lower than 1.5 eV related to low reflectance in the Vis-NIR range. Moreover, obtained histograms of grains, using scanning electron microscope, enabled the correlation between grains size and amount of lead titanate. We deduced from the ceramics surface morphology that marked porosity also induced reflectivity of low magnitude. We correlated the magnitude of the energy gap with phases of the BM-PT composite and with the electrical conductivity activation energy reported in the literature. Our results findings opened prospect studied materials for optical applications.
{"title":"Vis and NIR Diffused Reflectance Study in Disordered Bismuth Manganate ‒ Lead Titanate Ceramics","authors":"A. Molak, A. Szeremeta, J. Koperski","doi":"10.20944/preprints202110.0449.v1","DOIUrl":"https://doi.org/10.20944/preprints202110.0449.v1","url":null,"abstract":"This work shows a correlation between light reflectance, absorption, and morphologies of series of (1-x) BM–x PT, (x = 0.0, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24) ceramics composite. The (1-x) BM–x PT showed features of a black mirror with a low optical energy gap. The measured Vis-NIR diffused reflectance enabled the calculation of the energy gap using the modified Kubelka-Munk function. The estimated energy gap was lower than 1.5 eV related to low reflectance in the Vis-NIR range. Moreover, obtained histograms of grains, using scanning electron microscope, enabled the correlation between grains size and amount of lead titanate. We deduced from the ceramics surface morphology that marked porosity also induced reflectivity of low magnitude. We correlated the magnitude of the energy gap with phases of the BM-PT composite and with the electrical conductivity activation energy reported in the literature. Our results findings opened prospect studied materials for optical applications.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88705763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-10DOI: 10.3390/electronicmat2040033
Jignesh Vanjaria, V. Hariharan, A. Arjunan, Yanze Wu, G. Tompa, Hongbin Yu
Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH4) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (>10−6 Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy.
{"title":"One-Step Cost-Effective Growth of High-Quality Epitaxial Ge Films on Si (100) Using a Simplified PECVD Reactor","authors":"Jignesh Vanjaria, V. Hariharan, A. Arjunan, Yanze Wu, G. Tompa, Hongbin Yu","doi":"10.3390/electronicmat2040033","DOIUrl":"https://doi.org/10.3390/electronicmat2040033","url":null,"abstract":"Heteroepitaxial growth of Ge films on Si is necessary for the progress of integrated Si photonics technology. In this work, an in-house assembled plasma enhanced chemical vapor deposition reactor was used to grow high quality epitaxial Ge films on Si (100) substrates. Low economic and thermal budget were accomplished by the avoidance of ultra-high vacuum conditions or high temperature substrate pre-deposition bake for the process. Films were deposited with and without plasma assistance using germane (GeH4) precursor in a single step at process temperatures of 350–385 °C and chamber pressures of 1–10 Torr at various precursor flow rates. Film growth was realized at high ambient chamber pressures (>10−6 Torr) by utilizing a rigorous ex situ substrate cleaning process, closely controlling substrate loading times, chamber pumping and the dead-time prior to the initiation of film growth. Plasma allowed for higher film deposition rates at lower processing temperatures. An epitaxial growth was confirmed by X-Ray diffraction studies, while crystalline quality of the films was verified by X-ray rocking curve, Raman spectroscopy, transmission electron microscopy and infra-red spectroscopy.","PeriodicalId":18610,"journal":{"name":"Modern Electronic Materials","volume":"44 3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85025817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-10-08DOI: 10.3390/electronicmat2040032
B. Singh, S. Sikarwar, K. Pandey, R. Manohar, M. Depriester, D. Singh
In this paper, we investigate a commercial nematic liquid crystal (LC) mixture namely E7 dispersed with small concentrations of multi-walled carbon nanotubes (MWCNTs). The dielectric and electro-optical characterizations have been carried out in the homogeneously and vertically aligned LC cells. The electro-optical response of LC molecules has been enhanced by 60% after the addition of MWCNTs, which is attributed to the reduced rotational viscosity in the composites. MWCNTs act like barricades for ionic impurities by reducing them up to ∼34.3% within the dispersion limit of 0.05 wt%. The nematic–isotropic phase transition temperature (TNI) of the E7 LC has also been shifted towards the higher temperature, resulting in a more ordered nematic phase. The enhanced birefringence and orientational order parameter in the LC-MWCNTs are attributed to π-π electron stacking between the LC molecules and the MWCNTs. The outlined merits of the LC-MWCNTs composites evince their suitability for ultrafast nematic-based electro-optical devices.
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