Pub Date : 2024-11-15DOI: 10.1016/j.jcrysgro.2024.128003
A. Modrić-Šahbazović , A. Smajlagić , Z. Sakić , M. Novaković , N. Latas , M. Popović , M. Đekić , S. Isaković , A. Salčinović Fetić
This study examines the synthesis of ZnO powder via the sol–gel method at temperatures of 25 °C and 60 °C. Characterization was conducted using standard techniques to investigate how these temperature conditions influence the physicochemical properties of the resulting material. XRD analysis confirmed high crystallinity with a pure hexagonal wurtzite structure, with average crystallite sizes of approximately 20 nm at 25 °C and 38 nm at 60 °C. Both SEM and TEM techniques established needle-like nanorods at 25 °C and nanoflower-like structures at 60 °C. Analyzing the high-resolution XPS spectra of the Zn2p and O1s photoelectron lines revealed a predominant Zn(II) state, with the contribution of ZnO increasing from 14.6 at.% to 41.6 at.% at higher temperatures. This change was accompanied by a decrease in defective oxygen and water content. Furthermore, DSC analysis revealed significant differences in thermal properties of ZnO powders synthesized at 25 °C and 60 °C, with distinct endothermic peaks around 120 °C corresponding to the evaporation of the solvent used in the synthesis process. The energy required for phase transitions was notably higher for the 25 °C synthesis, indicating greater thermal stability and energy demands compared to the 60 °C synthesis.
{"title":"Role of synthesis temperature in the formation of ZnO nanoparticles via the Sol-Gel process","authors":"A. Modrić-Šahbazović , A. Smajlagić , Z. Sakić , M. Novaković , N. Latas , M. Popović , M. Đekić , S. Isaković , A. Salčinović Fetić","doi":"10.1016/j.jcrysgro.2024.128003","DOIUrl":"10.1016/j.jcrysgro.2024.128003","url":null,"abstract":"<div><div>This study examines the synthesis of ZnO powder via the sol–gel method at temperatures of 25 °C and 60 °C. Characterization was conducted using standard techniques to investigate how these temperature conditions influence the physicochemical properties of the resulting material. XRD analysis confirmed high crystallinity with a pure hexagonal wurtzite structure, with average crystallite sizes of approximately 20 nm at 25 °C and 38 nm at 60 °C. Both SEM and TEM techniques established needle-like nanorods at 25 °C and nanoflower-like structures at 60 °C. Analyzing the high-resolution XPS spectra of the Zn2p and O1s photoelectron lines revealed a predominant Zn(II) state, with the contribution of ZnO increasing from 14.6 at.% to 41.6 at.% at higher temperatures. This change was accompanied by a decrease in defective oxygen and water content. Furthermore, DSC analysis revealed significant differences in thermal properties of ZnO powders synthesized at 25 °C and 60 °C, with distinct endothermic peaks around 120 °C corresponding to the evaporation of the solvent used in the synthesis process. The energy required for phase transitions was notably higher for the 25 °C synthesis, indicating greater thermal stability and energy demands compared to the 60 °C synthesis.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 128003"},"PeriodicalIF":1.7,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.jcrysgro.2024.127974
Chufeng Hou , Kai Liang , Ziyu Yang , Qiang Wang , Yuefei Zhang , Fei Chen
The Atomic Layer Deposition (ALD) technique is regarded as an effective method for fabricating high-quality Ga2O3 thin films. Trimethyl gallium (TMG), with its high vapor pressure at room temperature (227 Torr), is widely utilized as a gallium precursor in this technique. For oxygen precursors, common choices include O3 and O2 plasma. However, the impact of H2O as an oxygen precursor on Ga2O3 thin films during Thermal Atomic Layer Deposition (TALD) remains insufficiently explored. This study investigates the temperature window and growth characteristics of Ga2O3 thin films, deposited using TMG and H2O as precursors, on sapphire substrates within the temperature range of 250–500 °C. At 250 °C, deposited Ga2O3 films exhibit an amorphous structure, whereas within the 300–500 °C substrate temperature range, they transition to the α-phase. The half-peak width (FWHM) narrows as the temperature increases, with characteristic peaks of the (0006) facets shifting to higher angles at 500 °C. STEM analysis reveals complete coherence between α-Ga2O3 films and the sapphire substrate, indicating a pseudo-crystalline structure formation. The growth rate of the films at 450 °C is 0.083 Å/cycle. Ga2O3 films prepared with H2O as the oxygen precursor exhibit Ga-rich properties, with (Ga + Al)/O atomic ratios between 0.88 and 0.91 across the 250–500 °C temperature range. The films’ roughness (Ra) ranges from 0.453 to 0.646 nm. Island-like particles form on the film surface within the 400–500 °C range, smoothing out as the temperature rises. The film’s band gap peaks at 5.50 eV at 450 °C. The reaction of TMG with H2O on sapphire substrates yields Ga2O3 films and CH4 by-products, akin to the trimethylaluminum process.
{"title":"Thermal atomic layer deposition of Ga2O3 films using trimethylgallium and H2O","authors":"Chufeng Hou , Kai Liang , Ziyu Yang , Qiang Wang , Yuefei Zhang , Fei Chen","doi":"10.1016/j.jcrysgro.2024.127974","DOIUrl":"10.1016/j.jcrysgro.2024.127974","url":null,"abstract":"<div><div>The Atomic Layer Deposition (ALD) technique is regarded as an effective method for fabricating high-quality Ga<sub>2</sub>O<sub>3</sub> thin films. Trimethyl gallium (TMG), with its high vapor pressure at room temperature (227 Torr), is widely utilized as a gallium precursor in this technique. For oxygen precursors, common choices include O<sub>3</sub> and O<sub>2</sub> plasma. However, the impact of H<sub>2</sub>O as an oxygen precursor on Ga<sub>2</sub>O<sub>3</sub> thin films during Thermal Atomic Layer Deposition (TALD) remains insufficiently explored. This study investigates the temperature window and growth characteristics of Ga<sub>2</sub>O<sub>3</sub> thin films, deposited using TMG and H<sub>2</sub>O as precursors, on sapphire substrates within the temperature range of 250–500 °C. At 250 °C, deposited Ga<sub>2</sub>O<sub>3</sub> films exhibit an amorphous structure, whereas within the 300–500 °C substrate temperature range, they transition to the α-phase. The half-peak width (FWHM) narrows as the temperature increases, with characteristic peaks of the (0006) facets shifting to higher angles at 500 °C. STEM analysis reveals complete coherence between α-Ga<sub>2</sub>O<sub>3</sub> films and the sapphire substrate, indicating a pseudo-crystalline structure formation. The growth rate of the films at 450 °C is 0.083 Å/cycle. Ga<sub>2</sub>O<sub>3</sub> films prepared with H<sub>2</sub>O as the oxygen precursor exhibit Ga-rich properties, with (Ga + Al)/O atomic ratios between 0.88 and 0.91 across the 250–500 °C temperature range. The films’ roughness (Ra) ranges from 0.453 to 0.646 nm. Island-like particles form on the film surface within the 400–500 °C range, smoothing out as the temperature rises. The film’s band gap peaks at 5.50 eV at 450 °C. The reaction of TMG with H<sub>2</sub>O on sapphire substrates yields Ga<sub>2</sub>O<sub>3</sub> films and CH<sub>4</sub> by-products, akin to the trimethylaluminum process.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127974"},"PeriodicalIF":1.7,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-10DOI: 10.1016/j.jcrysgro.2024.127993
Lusong Wang , Xianbo Li , Yuqi He , Hu Huang , Yawen Du
α-calcium sulfate hemihydrate (α-CSH) is a green building material. The synthesis of α-CSH from industrial phosphogypsum (PG) in Na2SO4 solution is a promising technique, but Na impurity may be introduced into α-CSH crystal. In this study, the doping behavior of Na into α-CSH was investigated, and the occurrence state of Na in α-CSH was clarified. The results show that Na impurity was doped into α-CSH in the form of Na2Ca5(SO4)2·3H2O, and the doping content of Na2O in α-CSH increases with the Na2SO4 concentration and reaction time. Density functional theory (DFT) calculation shows Na impurity is likely to be doped into α-CSH crystal through interstitial filling. Unfortunately, the doping of Na into α-CSH could cause a visible frost phenomenon for the hardened plaster, which has a negative impact on the practical utilization of α-CSH.
半水硫酸钙（α-CSH）是一种绿色建材。以工业磷石膏（PG）为原料在 Na2SO4 溶液中合成 α-CSH 是一种很有前景的技术，但 Na 杂质可能会引入 α-CSH 晶体中。本研究考察了 Na 在 α-CSH 中的掺杂行为，并阐明了 Na 在 α-CSH 中的出现状态。结果表明，Na杂质以Na2Ca5(SO4)2-3H2O的形式掺入α-CSH中，且α-CSH中Na2O的掺入量随Na2SO4浓度和反应时间的增加而增加。密度泛函理论（DFT）计算表明，Na 杂质很可能是通过间隙填充掺杂到 α-CSH 晶体中的。遗憾的是，Na 在 α-CSH 中的掺杂会导致硬化石膏出现明显的结霜现象，这对α-CSH 的实际应用产生了负面影响。
{"title":"Doping behavior and occurrence state of Na impurity in α-calcium sulfate hemihydrate prepared in Na2SO4 solution","authors":"Lusong Wang , Xianbo Li , Yuqi He , Hu Huang , Yawen Du","doi":"10.1016/j.jcrysgro.2024.127993","DOIUrl":"10.1016/j.jcrysgro.2024.127993","url":null,"abstract":"<div><div>α-calcium sulfate hemihydrate (α-CSH) is a green building material. The synthesis of α-CSH from industrial phosphogypsum (PG) in Na<sub>2</sub>SO<sub>4</sub> solution is a promising technique, but Na impurity may be introduced into α-CSH crystal. In this study, the doping behavior of Na into α-CSH was investigated, and the occurrence state of Na in α-CSH was clarified. The results show that Na impurity was doped into α-CSH in the form of Na<sub>2</sub>Ca<sub>5</sub>(SO<sub>4</sub>)<sub>2</sub>·3H<sub>2</sub>O, and the doping content of Na<sub>2</sub>O in α-CSH increases with the Na<sub>2</sub>SO<sub>4</sub> concentration and reaction time. Density functional theory (DFT) calculation shows Na impurity is likely to be doped into α-CSH crystal through interstitial filling. Unfortunately, the doping of Na into α-CSH could cause a visible frost phenomenon for the hardened plaster, which has a negative impact on the practical utilization of α-CSH.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127993"},"PeriodicalIF":1.7,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-07DOI: 10.1016/j.jcrysgro.2024.127992
Zhigang Lu , Jianfeng Pan , Hong Zhang , Chao Jiang , Wenming Yang
Density functional theory was used to analyze the formation of InGaN from trimethylindium (TMIn) and trimethylgallium (TMGa) by metalorganic chemical vapor deposition in ammonia in terms of the reaction between trimethyl compounds and NH3, as well as the subsequent reactions of the key amino species DMInNH2. The calculation model is established in GAUSSIAN 09, and the results obtained by the calculation model are proved to be reliable by comparing with the previous research results. Reaction pathways were assumed and the Gibbs free energy and activation free energy calculation were conducted at different temperatures. TMIn and TMGa can undergo adduct reactions with the first NH3 molecule at reaction temperatures below 596 K and 465 K, respectively, but they cannot further react with the second NH3 molecule to form additional products. The temperature range for adduct reactions between TMIn and NH3 is wider compared to TMGa and NH3. In the absence of H radicals in the reaction chamber, DMInNH2 does not undergo spontaneous CH3 radical elimination reactions or CH4 elimination reactions. Instead, DMInNH2 is more inclined to undergo dimerization reactions and CH4 elimination reactions with NH3, leading to the formation of subsequent products, In(NH2)3 and dimers. However, in the presence of H radicals in the reaction chamber, H radicals can facilitate the CH3 radical elimination reaction of DMInNH2 and also promote the NH2 radical elimination reaction of In(NH2)3, In(NH2)2 and InNH2, enabling these reactions to occur spontaneously within the studied temperature range. Consequently, the subsequent products of DMInNH2 become indium atoms and dimers.
{"title":"Quantum chemical study of trimethylindium and trimethylgallium gas-phase reaction pathways in InGaN MOCVD growth","authors":"Zhigang Lu , Jianfeng Pan , Hong Zhang , Chao Jiang , Wenming Yang","doi":"10.1016/j.jcrysgro.2024.127992","DOIUrl":"10.1016/j.jcrysgro.2024.127992","url":null,"abstract":"<div><div>Density functional theory was used to analyze the formation of InGaN from trimethylindium (TMIn) and trimethylgallium (TMGa) by metalorganic chemical vapor deposition in ammonia in terms of the reaction between trimethyl compounds and NH<sub>3</sub>, as well as the subsequent reactions of the key amino species DMInNH<sub>2</sub>. The calculation model is established in GAUSSIAN 09, and the results obtained by the calculation model are proved to be reliable by comparing with the previous research results. Reaction pathways were assumed and the Gibbs free energy and activation free energy calculation were conducted at different temperatures. TMIn and TMGa can undergo adduct reactions with the first NH<sub>3</sub> molecule at reaction temperatures below 596 K and 465 K, respectively, but they cannot further react with the second NH<sub>3</sub> molecule to form additional products. The temperature range for adduct reactions between TMIn and NH<sub>3</sub> is wider compared to TMGa and NH<sub>3</sub>. In the absence of H radicals in the reaction chamber, DMInNH<sub>2</sub> does not undergo spontaneous CH<sub>3</sub> radical elimination reactions or CH<sub>4</sub> elimination reactions. Instead, DMInNH<sub>2</sub> is more inclined to undergo dimerization reactions and CH<sub>4</sub> elimination reactions with NH<sub>3</sub>, leading to the formation of subsequent products, In(NH<sub>2</sub>)<sub>3</sub> and dimers. However, in the presence of H radicals in the reaction chamber, H radicals can facilitate the CH<sub>3</sub> radical elimination reaction of DMInNH<sub>2</sub> and also promote the NH<sub>2</sub> radical elimination reaction of In(NH<sub>2</sub>)<sub>3,</sub> In(NH<sub>2</sub>)<sub>2</sub> and InNH<sub>2</sub>, enabling these reactions to occur spontaneously within the studied temperature range. Consequently, the subsequent products of DMInNH<sub>2</sub> become indium atoms and dimers.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127992"},"PeriodicalIF":1.7,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Er:CaF2 crystal, characterized by low doping and high efficiency, is a suitable material for single-crystal fiber (SCF). 3 at.% Er:CaF2 SCFs were grown using the laser heated pedestal growth (LHPG) method. Significant oxidation-induced whitening phenomena were observed during growth. Increasing the growth rate helped mitigate further deterioration due to oxidation. This is likely because higher growth speeds allow the SCF to quickly move away from temperature ranges conducive to oxidation. As oxidation progressed, the phonon energy of 3 at.% Er:CaF2 SCF increased, causing the emission intensity at ∼ 1 μm to decrease from 77 % in the initial source rod to 6 % in the fully whitened state. Additionally, the lifetime of the 4I11/2 level decreased by approximately 10 times, from 8.988 ms to 0.822 ms. Continuous laser output at ∼ 2.8 μm was achieved using the transparent portion of 3 at.% Er:CaF2 SCF. With an output mirror transmission of 2 %, a maximum output power of 251 mW and a slope efficiency of 15.9 % were obtained. The laser experiment demonstrated the potential application of LHPG-grown Er:CaF2 SCF in ∼ 2.8 μm lasers, but further performance enhancement requires additional strategies to address oxidation issues. This work provides valuable insights into the growth of Er:CaF2 SCF using the LHPG method.
{"title":"Characterization and mid-infrared laser operation in Er:CaF2 single crystal fiber grown by the laser heated pedestal growth method","authors":"Xu Wu, Zhen Zhang, Yunfei Wang, Shaochen Liu, Zhonghan Zhang, Liangbi Su, Anhua Wu","doi":"10.1016/j.jcrysgro.2024.127991","DOIUrl":"10.1016/j.jcrysgro.2024.127991","url":null,"abstract":"<div><div>Er:CaF<sub>2</sub> crystal, characterized by low doping and high efficiency, is a suitable material for single-crystal fiber (SCF). 3 at.% Er:CaF<sub>2</sub> SCFs were grown using the laser heated pedestal growth (LHPG) method. Significant oxidation-induced whitening phenomena were observed during growth. Increasing the growth rate helped mitigate further deterioration due to oxidation. This is likely because higher growth speeds allow the SCF to quickly move away from temperature ranges conducive to oxidation. As oxidation progressed, the phonon energy of 3 at.% Er:CaF<sub>2</sub> SCF increased, causing the emission intensity at ∼ 1 μm to decrease from 77 % in the initial source rod to 6 % in the fully whitened state. Additionally, the lifetime of the <sup>4</sup>I<sub>11/2</sub> level decreased by approximately 10 times, from 8.988 ms to 0.822 ms. Continuous laser output at ∼ 2.8 μm was achieved using the transparent portion of 3 at.% Er:CaF<sub>2</sub> SCF. With an output mirror transmission of 2 %, a maximum output power of 251 mW and a slope efficiency of 15.9 % were obtained. The laser experiment demonstrated the potential application of LHPG-grown Er:CaF<sub>2</sub> SCF in ∼ 2.8 μm lasers, but further performance enhancement requires additional strategies to address oxidation issues. This work provides valuable insights into the growth of Er:CaF<sub>2</sub> SCF using the LHPG method.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127991"},"PeriodicalIF":1.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652405","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-06DOI: 10.1016/j.jcrysgro.2024.127990
Jiangtao Fan , Zhanggui Hu , Yicheng Wu
The co-doped TiO2 polycrystalline ceramics have dramatic dielectric behavior (>104), but its source is still not completely clarified. Compared to ceramic materials, single crystals can maintain most of the original properties of the material and eliminate the grain boundary and pore interferences, thus facilitating the exploration of the source of the dielectric properties. Here, we chose Gd3+ with a moderate ionic radius as the acceptor ion and Ta5+ as the donor, preparing (Gd0.5Ta0.5)0.01Ti0.99O2 single crystals by the optical traveling floating zone method to investigate giant dielectric properties. It was found that a dielectric constant (ε′ ∼1.5 × 104), and a dielectric loss (tanδ ∼ 0.07) were achieved simultaneously in (Gd0.5Ta0.5)0.01Ti0.99O2 single crystals at 105Hz. Electrochemical impedance spectroscopy and XPS analyses indicate that the high dielectric properties are mainly attributed to electrons pinning defective dipoles clusters. In addition, dielectric relaxation behavior under DC bias suggests that electrode effects also affect the dielectric constant. This study provides insights for the origin of the large dielectric constant and the growth of single crystals in TiO2-based materials.
{"title":"Origin of giant dielectric constant in Ta+Gd co-doped TiO2 single crystals by optical traveling floating zone method","authors":"Jiangtao Fan , Zhanggui Hu , Yicheng Wu","doi":"10.1016/j.jcrysgro.2024.127990","DOIUrl":"10.1016/j.jcrysgro.2024.127990","url":null,"abstract":"<div><div>The co-doped TiO<sub>2</sub> polycrystalline ceramics have dramatic dielectric behavior (>10<sup>4</sup>), but its source is still not completely clarified. Compared to ceramic materials, single crystals can maintain most of the original properties of the material and eliminate the grain boundary and pore interferences, thus facilitating the exploration of the source of the dielectric properties. Here, we chose Gd<sup>3+</sup> with a moderate ionic radius as the acceptor ion and Ta<sup>5+</sup> as the donor, preparing (Gd<sub>0.5</sub>Ta<sub>0.5</sub>)<sub>0.01</sub>Ti<sub>0.99</sub>O<sub>2</sub> single crystals by the optical traveling floating zone method to investigate giant dielectric properties. It was found that a dielectric constant (<em>ε</em>′ ∼1.5 × 10<sup>4</sup>), and a dielectric loss (tanδ ∼ 0.07) were achieved simultaneously in (Gd<sub>0.5</sub>Ta<sub>0.5</sub>)<sub>0.01</sub>Ti<sub>0.99</sub>O<sub>2</sub> single crystals at 10<sup>5</sup>Hz. Electrochemical impedance spectroscopy and XPS analyses indicate that the high dielectric properties are mainly attributed to electrons pinning defective dipoles clusters. In addition, dielectric relaxation behavior under DC bias suggests that electrode effects also affect the dielectric constant. This study provides insights for the origin of the large dielectric constant and the growth of single crystals in TiO<sub>2</sub>-based materials.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127990"},"PeriodicalIF":1.7,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.jcrysgro.2024.127989
Hao Zhou , Yiqiao Chen , Chang Liu
The growth conditions for InAs homoepitaxy by molecular beam epitaxy were comprehensively studied across a broad spectrum of substrate temperatures, As2/In flux ratios, and growth rates. It was found that the surface morphology and overall quality of the InAs layers were significantly influenced by these parameters. Optimal conditions, including a lower growth temperature, reduced As2 flux, and slower growth rate, were pivotal in achieving high-quality InAs layers. Two primary characterization techniques, differential interference contrast microscopy and atomic force microscopy, were employed to evaluate the material quality. High-quality InAs homoepitaxial layers were successfully grown at a substrate temperature of 455 °C and a growth rate of 0.33 monolayers per second (ML/s). These layers exhibited a remarkably low defect density of approximately 300 defects per square centimeter, which is over an order of magnitude lower than previously reported, and a notably low root-mean-square roughness of 0.116 nm. At a growth rate of 0.33 ML/s, the growth temperature range for InAs homoepitaxial layers was found to be quite broad, whereas the As2/In flux ratio remained within a narrow range. This study underscores the critical role of precise control over growth parameters in the molecular beam epitaxy process for producing high-quality InAs homoepitaxial layers.
{"title":"High-quality InAs homoepitaxial layers grown by molecular beam epitaxy","authors":"Hao Zhou , Yiqiao Chen , Chang Liu","doi":"10.1016/j.jcrysgro.2024.127989","DOIUrl":"10.1016/j.jcrysgro.2024.127989","url":null,"abstract":"<div><div>The growth conditions for InAs homoepitaxy by molecular beam epitaxy were comprehensively studied across a broad spectrum of substrate temperatures, As2/In flux ratios, and growth rates. It was found that the surface morphology and overall quality of the InAs layers were significantly influenced by these parameters. Optimal conditions, including a lower growth temperature, reduced As2 flux, and slower growth rate, were pivotal in achieving high-quality InAs layers. Two primary characterization techniques, differential interference contrast microscopy and atomic force microscopy, were employed to evaluate the material quality. High-quality InAs homoepitaxial layers were successfully grown at a substrate temperature of 455 °C and a growth rate of 0.33 monolayers per second (ML/s). These layers exhibited a remarkably low defect density of approximately 300 defects per square centimeter, which is over an order of magnitude lower than previously reported, and a notably low root-mean-square roughness of 0.116 nm. At a growth rate of 0.33 ML/s, the growth temperature range for InAs homoepitaxial layers was found to be quite broad, whereas the As2/In flux ratio remained within a narrow range. This study underscores the critical role of precise control over growth parameters in the molecular beam epitaxy process for producing high-quality InAs homoepitaxial layers.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127989"},"PeriodicalIF":1.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.jcrysgro.2024.127984
Souhaila Meneceur , Salah Eddine Laouini , Hamdi Ali Mohammed , Abderrhmane Bouafia , Chaima Salmi , Johar Amin Ahmed Abdullah , Fahad Alharthi
Nanomaterials and nanocomposites, known for their unique properties, are increasingly vital in diverse fields such as energy and environmental remediation. This study presents biogenically synthesized ZnO/CuO/Ni nanocomposites using Mentha Pulegium L. leaf extract. The investigation focuses on their applications in photocatalytic dye adsorption and hydrogen evolution. Characterization via XRD, FTIR spectroscopy, SEM, and UV–visible spectroscopy confirms the nanocomposites’ semiconducting nature with a narrow bandgap energy of 2.46 eV. Structural analysis reveals cubic crystal structures with an average crystallite size of 29.1 nm. Under solar irradiation, the nanocomposites exhibit exceptional photocatalytic activity, degrading 99 % of 4-BP and 98 % of TB. Moreover, they achieve a notable hydrogen evolution rate of 5.79 mmol/g over six hours. These results underscore the efficacy of ZnO/CuO/Ni nanocomposites as catalysts for sustainable energy and water purification. Employing Mentha Pulegium L. extract for environmentally friendly synthesis enhances their photocatalytic properties, offering a cost-effective route to sustainable energy and clean water technologies.
{"title":"Eco-Friendly ZnO/CuO/Ni Nanocomposites: Enhanced photocatalytic dye adsorption and hydrogen evolution for sustainable energy and water purification","authors":"Souhaila Meneceur , Salah Eddine Laouini , Hamdi Ali Mohammed , Abderrhmane Bouafia , Chaima Salmi , Johar Amin Ahmed Abdullah , Fahad Alharthi","doi":"10.1016/j.jcrysgro.2024.127984","DOIUrl":"10.1016/j.jcrysgro.2024.127984","url":null,"abstract":"<div><div>Nanomaterials and nanocomposites, known for their unique properties, are increasingly vital in diverse fields such as energy and environmental remediation. This study presents biogenically synthesized ZnO/CuO/Ni nanocomposites using <em>Mentha Pulegium L.</em> leaf extract. The investigation focuses on their applications in photocatalytic dye adsorption and hydrogen evolution. Characterization via XRD, FTIR spectroscopy, SEM, and UV–visible spectroscopy confirms the nanocomposites’ semiconducting nature with a narrow bandgap energy of 2.46 eV. Structural analysis reveals cubic crystal structures with an average crystallite size of 29.1 nm. Under solar irradiation, the nanocomposites exhibit exceptional photocatalytic activity, degrading 99 % of 4-BP and 98 % of TB. Moreover, they achieve a notable hydrogen evolution rate of 5.79 mmol/g over six hours. These results underscore the efficacy of ZnO/CuO/Ni nanocomposites as catalysts for sustainable energy and water purification. Employing <em>Mentha Pulegium L.</em> extract for environmentally friendly synthesis enhances their photocatalytic properties, offering a cost-effective route to sustainable energy and clean water technologies.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127984"},"PeriodicalIF":1.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.jcrysgro.2024.127982
Shunta Harada , Kenta Murayama
This short review provides an overview of advancements in the characterization of defects in silicon carbide (SiC) wafers using polarized light observation. SiC, which has a wide bandgap and excellent thermal and electrical properties, is widely used in power devices. However, various defects such as threading screw dislocations (TSD), threading edge dislocations (TED), and basal plane dislocations (BPD) can significantly affect device performance and reliability. Polarized light observation offers a nondestructive method for visualizing these defects and analyzing the stress fields induced within the SiC crystal structure. This paper summarizes recent developments in this technique, including the application of analyzer rotation to enhance the contrast in defect visualization. Furthermore, the development of automated systems for rapid wafer evaluation is discussed, highlighting the role of polarized light observation in improving quality control and production efficiency in SiC power device manufacturing.
这篇短文概述了利用偏振光观测碳化硅（SiC）晶片缺陷表征方面的进展。碳化硅具有宽带隙和优异的热性能和电性能，被广泛应用于功率器件中。然而，各种缺陷，如螺纹螺旋位错（TSD）、螺纹边缘位错（TED）和基底面位错（BPD）会严重影响器件的性能和可靠性。偏振光观测提供了一种无损方法，可用于观察这些缺陷并分析在 SiC 晶体结构中引起的应力场。本文总结了这一技术的最新发展，包括应用分析仪旋转来增强缺陷可视化的对比度。此外，本文还讨论了用于快速晶片评估的自动化系统的开发，强调了偏振光观测在提高碳化硅功率器件制造的质量控制和生产效率方面的作用。
{"title":"Advances in defect characterization techniques using polarized light observation in SiC wafers for power devices","authors":"Shunta Harada , Kenta Murayama","doi":"10.1016/j.jcrysgro.2024.127982","DOIUrl":"10.1016/j.jcrysgro.2024.127982","url":null,"abstract":"<div><div>This short review provides an overview of advancements in the characterization of defects in silicon carbide (SiC) wafers using polarized light observation. SiC, which has a wide bandgap and excellent thermal and electrical properties, is widely used in power devices. However, various defects such as threading screw dislocations (TSD), threading edge dislocations (TED), and basal plane dislocations (BPD) can significantly affect device performance and reliability. Polarized light observation offers a nondestructive method for visualizing these defects and analyzing the stress fields induced within the SiC crystal structure. This paper summarizes recent developments in this technique, including the application of analyzer rotation to enhance the contrast in defect visualization. Furthermore, the development of automated systems for rapid wafer evaluation is discussed, highlighting the role of polarized light observation in improving quality control and production efficiency in SiC power device manufacturing.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127982"},"PeriodicalIF":1.7,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-04DOI: 10.1016/j.jcrysgro.2024.127973
Rasmus A.X. Persson
In industrial-scale crystallization, secondary nucleation is the most important type of nucleation. In most cases, this phenomenon can be adequately explained as the result of mechanical forces that break existing crystallites apart, the strength of the effect being a smooth function of supersaturation and stirring vigor. However, in some special cases, crystallites of other polymorphs appear and/or no nucleation occurs except at a catastrophic rate above a supersaturation threshold, mimicking primary nucleation. In this paper, we review published theories for this latter type of secondary nucleation, for which we find contradicting explanations in the literature. We divide these explanations into two broad classes, depending on whether the secondary nucleation is mediated through local deviations of the bulk thermodynamic state variables (indirect effects) or directly through the interaction energy of the surface and growth units (direct effects). We argue that theoretical explanations of the second type are insufficient and while we can find no conclusive and theoretically consistent explanation for this well-established experimental phenomenon, it is hoped that this review will stimulate further research into this puzzle.
{"title":"“Catalyzed” nucleation: A critical review of proposed theories","authors":"Rasmus A.X. Persson","doi":"10.1016/j.jcrysgro.2024.127973","DOIUrl":"10.1016/j.jcrysgro.2024.127973","url":null,"abstract":"<div><div>In industrial-scale crystallization, secondary nucleation is the most important type of nucleation. In most cases, this phenomenon can be adequately explained as the result of mechanical forces that break existing crystallites apart, the strength of the effect being a smooth function of supersaturation and stirring vigor. However, in some special cases, crystallites of other polymorphs appear and/or no nucleation occurs except at a catastrophic rate above a supersaturation threshold, mimicking primary nucleation. In this paper, we review published theories for this latter type of secondary nucleation, for which we find contradicting explanations in the literature. We divide these explanations into two broad classes, depending on whether the secondary nucleation is mediated through local deviations of the bulk thermodynamic state variables (indirect effects) or directly through the interaction energy of the surface and growth units (direct effects). We argue that theoretical explanations of the second type are insufficient and while we can find no conclusive and theoretically consistent explanation for this well-established experimental phenomenon, it is hoped that this review will stimulate further research into this puzzle.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"650 ","pages":"Article 127973"},"PeriodicalIF":1.7,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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