Pub Date : 2025-10-13DOI: 10.1016/j.jcrysgro.2025.128343
Debajani Rout , R. Kulkarni , A. Thamizhavel , Santosh Kumar
We report the growth of single crystals of the non-centrosymmetric material YCoC2 by the Czochralski technique using a tetra arc furnace. This compound belongs to the family of rare-earth transition-metal carbides, the members of which exhibit a wide range of interesting phenomena including topological semimetallic behaviour. We have investigated the magnetic and transport properties of YCoC2. The results of resistivity measurements revealed a typical metallic behaviour across the temperature range, 4 < T < 300 K. At T = 3.9(1) K, a transition in both magnetization and resistivity measurements has been observed. This feature has been explored in detail with the temperature-dependent magnetization M(T) and resistivity ρ(T) measurements carried out at different magnetic fields.
本文报道了在四弧炉中，用Czochralski法生长非中心对称材料YCoC2的单晶。该化合物属于稀土过渡金属碳化物家族，其成员表现出广泛的有趣现象，包括拓扑半金属行为。我们研究了YCoC2的磁性和输运性质。电阻率测量结果显示在4 <； T <； 300 K的温度范围内具有典型的金属行为。在T = 3.9(1) K时，磁化率和电阻率测量值都发生了转变。在不同磁场下进行的温度相关磁化强度M(T)和电阻率ρ(T)测量详细探讨了这一特征。
{"title":"Single crystal growth, study of magnetic and transport properties in the noncentrosymmetric material YCoC2","authors":"Debajani Rout , R. Kulkarni , A. Thamizhavel , Santosh Kumar","doi":"10.1016/j.jcrysgro.2025.128343","DOIUrl":"10.1016/j.jcrysgro.2025.128343","url":null,"abstract":"<div><div>We report the growth of single crystals of the non-centrosymmetric material YCoC<sub>2</sub> by the Czochralski technique using a tetra arc furnace. This compound belongs to the family of rare-earth transition-metal carbides, the members of which exhibit a wide range of interesting phenomena including topological semimetallic behaviour. We have investigated the magnetic and transport properties of YCoC<sub>2</sub>. The results of resistivity measurements revealed a typical metallic behaviour across the temperature range, 4 < <em>T</em> < 300 K. At <em>T</em> = 3<em>.</em>9(1) K, a transition in both magnetization and resistivity measurements has been observed. This feature has been explored in detail with the temperature-dependent magnetization <em>M</em>(<em>T</em>) and resistivity <em>ρ</em>(<em>T</em>) measurements carried out at different magnetic fields.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128343"},"PeriodicalIF":2.0,"publicationDate":"2025-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326238","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 : 2025-10-12DOI: 10.1016/j.jcrysgro.2025.128366
Ya Li , Jing Liang , Yucong Lin , Yu Lu , Zhifeng Wang , Houfu Dai , Jian Li
Zinc oxide (ZnO) films hold significant value in the field of optoelectronic devices due to their exceptional properties as wide bandgap semiconductors. Although Metal-Organic Chemical Vapor Deposition (MOCVD) technology enables the production of high-quality thin film epitaxy, its industrial application continues to encounter persistent challenges related to inadequate deposition uniformity and efficiency. In this research, we employed a novel vertical reaction chamber ZnO-MOCVD device to systematically investigate the synergistic mechanisms governing multiple parameters—including MO source, O source, Ar carrier gas flow rate, and observation window flow rate—through multi-physics coupled numerical simulations and orthogonal experimental design. The results demonstrate that precisely adjusting the O source flow velocity effectively mitigates vortex phenomena within the turntable, thereby stabilizing the laminar flow state. Increasing the inlet flow rate suppresses the thermal buoyancy effect and reduces the risk of gas-phase pre-reaction. The synergistic regulation of MO and O flow velocities significantly enhances the uniformity of diethyl zinc (DEZn) and oxygen (O2) distribution. Orthogonal analysis successfully identified the optimal combination of process parameters, resulting in an exceptional deposition rate (0.2049 μm/h) and a coefficient of variation (4 %), thereby fully validating the effectiveness of the multi-parameter collaborative optimization strategy. This research provides an important theoretical foundation for MOCVD equipment process design and offers crucial guidance for advancing the industrial preparation of high-performance ZnO films.
{"title":"Research on MOCVD structure design and process parameters based on CFD numerical simulation","authors":"Ya Li , Jing Liang , Yucong Lin , Yu Lu , Zhifeng Wang , Houfu Dai , Jian Li","doi":"10.1016/j.jcrysgro.2025.128366","DOIUrl":"10.1016/j.jcrysgro.2025.128366","url":null,"abstract":"<div><div>Zinc oxide (ZnO) films hold significant value in the field of optoelectronic devices due to their exceptional properties as wide bandgap semiconductors. Although Metal-Organic Chemical Vapor Deposition (MOCVD) technology enables the production of high-quality thin film epitaxy, its industrial application continues to encounter persistent challenges related to inadequate deposition uniformity and efficiency. In this research, we employed a novel vertical reaction chamber ZnO-MOCVD device to systematically investigate the synergistic mechanisms governing multiple parameters—including MO source, O source, Ar carrier gas flow rate, and observation window flow rate—through multi-physics coupled numerical simulations and orthogonal experimental design. The results demonstrate that precisely adjusting the O source flow velocity effectively mitigates vortex phenomena within the turntable, thereby stabilizing the laminar flow state. Increasing the inlet flow rate suppresses the thermal buoyancy effect and reduces the risk of gas-phase pre-reaction. The synergistic regulation of MO and O flow velocities significantly enhances the uniformity of diethyl zinc (DEZn) and oxygen (O<sub>2</sub>) distribution. Orthogonal analysis successfully identified the optimal combination of process parameters, resulting in an exceptional deposition rate (0.2049 μm/h) and a coefficient of variation (4 %), thereby fully validating the effectiveness of the multi-parameter collaborative optimization strategy. This research provides an important theoretical foundation for MOCVD equipment process design and offers crucial guidance for advancing the industrial preparation of high-performance ZnO films.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128366"},"PeriodicalIF":2.0,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326235","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 : 2025-10-11DOI: 10.1016/j.jcrysgro.2025.128356
Yisong Yang , Sha Chen , Zhishun Wei , Ying Chang , Yan Xiong , Junxiang Zhao , Hu Zhu , Min Li , Qirui Yang , Guoqiang Yi
This study proposes a method involving stirring after a constant-temperature water bath in a salt solution to enhance the crystal size, overall homogeneity, and hydration strength of α-hemihydrate gypsum (α-HH). Utilizing by-product gypsum from the chlor-alkali industry as raw material, the influence of Mg2+ ions on phase evolution and final morphology was systematically investigated. During the constant-temperature water bath process in salt solution, the neutral MgSO40 ion pairs formed by Mg2+ and SO42- facilitated the dissolution of dihydrate gypsum (DH) while amplifying the solubility difference between α-HH and DH, thereby promoting preferential crystallization and precipitation of α-HH. Furthermore, Mg2+ inhibited crystal growth along the c-axis direction during α-HH development, effectively reducing the aspect ratio. The subsequent stirring process significantly increased secondary nucleation probability, enabling mutual adhesion among α-HH crystals of varying dimensions. This synergistic process ultimately yielded enlarged α-HH crystals with an average particle size of 143.21 μm and aspect ratio of 5.57. The flexural strength and absolute dry compressive strength of bulk samples prepared from these α-HH crystals are discussed in detail, demonstrating substantial improvements in mechanical properties compared to conventional preparation methods.
{"title":"Growth of large-sized α-HH via Mg2+-involved atmospheric salt bath-stirring strategy: crystallization mechanism and enhanced mechanical properties","authors":"Yisong Yang , Sha Chen , Zhishun Wei , Ying Chang , Yan Xiong , Junxiang Zhao , Hu Zhu , Min Li , Qirui Yang , Guoqiang Yi","doi":"10.1016/j.jcrysgro.2025.128356","DOIUrl":"10.1016/j.jcrysgro.2025.128356","url":null,"abstract":"<div><div>This study proposes a method involving stirring after a constant-temperature water bath in a salt solution to enhance the crystal size, overall homogeneity, and hydration strength of α-hemihydrate gypsum (α-HH). Utilizing by-product gypsum from the chlor-alkali industry as raw material, the influence of Mg<sup>2+</sup> ions on phase evolution and final morphology was systematically investigated. During the constant-temperature water bath process in salt solution, the neutral MgSO<sub>4</sub><sup>0</sup> ion pairs formed by Mg<sup>2+</sup> and SO<sub>4</sub><sup>2-</sup> facilitated the dissolution of dihydrate gypsum (DH) while amplifying the solubility difference between α-HH and DH, thereby promoting preferential crystallization and precipitation of α-HH. Furthermore, Mg<sup>2+</sup> inhibited crystal growth along the c-axis direction during α-HH development, effectively reducing the aspect ratio. The subsequent stirring process significantly increased secondary nucleation probability, enabling mutual adhesion among α-HH crystals of varying dimensions. This synergistic process ultimately yielded enlarged α-HH crystals with an average particle size of 143.21 μm and aspect ratio of 5.57. The flexural strength and absolute dry compressive strength of bulk samples prepared from these α-HH crystals are discussed in detail, demonstrating substantial improvements in mechanical properties compared to conventional preparation methods.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128356"},"PeriodicalIF":2.0,"publicationDate":"2025-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326233","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 : 2025-10-04DOI: 10.1016/j.jcrysgro.2025.128348
Jian Li , Yaxin Zhao , Xuan Wang , Chunyu Ma , Shuang Zhao , Hongsheng Liu , Karpinski Dzmitry , Fuwen Qin
The low-temperature growth of β-Ga2O3 thin films on FTO/glass substrates was achieved using ECR-PEMOCVD with TMGa and O2 as precursors, and their structural, optical, and electrical properties were systematically investigated. XRD results reveal a clear evolution in crystallinity: as the substrate temperature increased from 350 °C to 500 °C and the discharge pressure decreased from 2.0 Pa to 0.5 Pa, the β-Ga2O3 films transitioned from amorphous to polycrystalline, eventually exhibiting strong (110) preferred orientation. XPS analysis confirmed the n-type conductivity of the films. A vertical metal–semiconductor–metal (MSM) Schottky diode based on Ni/n-type β-Ga2O3/FTO demonstrated a high rectification ratio of 1.57 × 103 at ± 4 V, a Schottky barrier height of 0.8–0.9 eV, and a carrier concentration of approximately 2 × 1016 cm−3. These results suggest that ECR-PEMOCVD is a promising approach for the low-temperature deposition of β-Ga2O3 thin films, with great potential for vertical device applications under limited thermal budgets.
{"title":"Low-temperature ECR-PEMOCVD growth of β-Ga2O3 thin films on FTO/glass for potential vertical Schottky diode applications","authors":"Jian Li , Yaxin Zhao , Xuan Wang , Chunyu Ma , Shuang Zhao , Hongsheng Liu , Karpinski Dzmitry , Fuwen Qin","doi":"10.1016/j.jcrysgro.2025.128348","DOIUrl":"10.1016/j.jcrysgro.2025.128348","url":null,"abstract":"<div><div>The low-temperature growth of β-Ga<sub>2</sub>O<sub>3</sub> thin films on FTO/glass substrates was achieved using ECR-PEMOCVD with TMGa and O<sub>2</sub> as precursors, and their structural, optical, and electrical properties were systematically investigated. XRD results reveal a clear evolution in crystallinity: as the substrate temperature increased from 350 °C to 500 °C and the discharge pressure decreased from 2.0 Pa to 0.5 Pa, the β-Ga<sub>2</sub>O<sub>3</sub> films transitioned from amorphous to polycrystalline, eventually exhibiting strong (110) preferred orientation. XPS analysis confirmed the n-type conductivity of the films. A vertical metal–semiconductor–metal (MSM) Schottky diode based on Ni/n-type β-Ga<sub>2</sub>O<sub>3</sub>/FTO demonstrated a high rectification ratio of 1.57 × 10<sup>3</sup> at ± 4 V, a Schottky barrier height of 0.8–0.9 eV, and a carrier concentration of approximately 2 × 10<sup>16</sup> cm<sup>−3</sup>. These results suggest that ECR-PEMOCVD is a promising approach for the low-temperature deposition of β-Ga<sub>2</sub>O<sub>3</sub> thin films, with great potential for vertical device applications under limited thermal budgets.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128348"},"PeriodicalIF":2.0,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145264435","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 : 2025-10-03DOI: 10.1016/j.jcrysgro.2025.128354
D. Sasireka , N. Kavitha , T.Sathis Kumar , L.Bruno Chandrasekar
A novel dysprosium-doped zirconium ferrite was prepared by the chemical precipitation method. The doping concentration of dysprosium was set at 0 %, 2 %, and 4 %. The structural properties, such as crystalline size and strain, were examined. The doping tuned the morphology of the nanoparticles. The band gap of the material decreases as the doping of dysprosium increases. The degradation of methylene blue was examined under natural sunlight and 93.2 % degradation efficiency was achieved at 120 min. The doping enhances the degradation efficiency using the zirconium ferrite catalyst. The electrochemical properties of the prepared nanoparticles as electrodes in a supercapacitor were studied using cyclic voltammetry and the galvanostatic charge–discharge technique. The maximum specific capacitance of ∼ 375F/g was observed at the scan rate of 5 mV/s.
{"title":"Effect of dysprosium concentration on the photocatalytic and electrochemical properties of zirconium ferrite nanoparticles","authors":"D. Sasireka , N. Kavitha , T.Sathis Kumar , L.Bruno Chandrasekar","doi":"10.1016/j.jcrysgro.2025.128354","DOIUrl":"10.1016/j.jcrysgro.2025.128354","url":null,"abstract":"<div><div>A novel dysprosium-doped zirconium ferrite was prepared by the chemical precipitation method. The doping concentration of dysprosium was set at 0 %, 2 %, and 4 %. The structural properties, such as crystalline size and strain, were examined. The doping tuned the morphology of the nanoparticles. The band gap of the material decreases as the doping of dysprosium increases. The degradation of methylene blue was examined under natural sunlight and 93.2 % degradation efficiency was achieved at 120 min. The doping enhances the degradation efficiency using the zirconium ferrite catalyst. The electrochemical properties of the prepared nanoparticles as electrodes in a supercapacitor were studied using cyclic voltammetry and the galvanostatic charge–discharge technique. The maximum specific capacitance of ∼ 375F/g was observed at the scan rate of 5 mV/s.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128354"},"PeriodicalIF":2.0,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145264436","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}
The nucleation behaviour of d-mannitol polymorph which is influenced by supersaturation was scrutinized by swift cooling crystallization process in pure aqueous solution. During swift cooling, concentration of d-mannitol in the solution creates different level of relative supersaturation leads to substantial differences in induction time, nucleation and morphology of the resultant polymorphs. This technique is employed to generate wide range of relative supersaturation (0.159 < σ < 3.860) corresponds to the rapid decrease in the temperature from 55 °C to shifting temperature of 54–1 °C. Specifically, lower level of relative supersaturation promotes the stable form I polymorph, while the nucleation of form I and form II polymorph is flavoured in intermediate level. Conversely, higher level of relative supersaturation induces the formation of only metastable form II polymorph. In-situ optical microscopy was employed to analysis the morphology of the nucleated polymorphs. Further characterization was done to validate the internal structure and thermal stability of the grown polymorphs through powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses. Rietveld refinement was employed to confirm the structures of both polymorphs, supporting a reliable interpretation of the PXRD results. This work shows a key advantage in understanding the crystallization behaviour which can be employed for the nucleation of d-mannitol polymorphs without any external additives within the solution.
{"title":"Enhanced separation of d-mannitol polymorphs I and II via nucleation control in swift cooling crystallization","authors":"Lavanisadevi Subiramaniyam, Srinivasan Karuppannan","doi":"10.1016/j.jcrysgro.2025.128353","DOIUrl":"10.1016/j.jcrysgro.2025.128353","url":null,"abstract":"<div><div>The nucleation behaviour of <span>d</span>-mannitol polymorph which is influenced by supersaturation was scrutinized by swift cooling crystallization process in pure aqueous solution. During swift cooling, concentration of <span>d</span>-mannitol in the solution creates different level of relative supersaturation leads to substantial differences in induction time, nucleation and morphology of the resultant polymorphs. This technique is employed to generate wide range of relative supersaturation (0.159 < σ < 3.860) corresponds to the rapid decrease in the temperature from 55 °C to shifting temperature of 54–1 °C. Specifically, lower level of relative supersaturation promotes the stable form I polymorph, while the nucleation of form I and form II polymorph is flavoured in intermediate level. Conversely, higher level of relative supersaturation induces the formation of only metastable form II polymorph. In-situ optical microscopy was employed to analysis the morphology of the nucleated polymorphs. Further characterization was done to validate the internal structure and thermal stability of the grown polymorphs through powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) analyses. Rietveld refinement was employed to confirm the structures of both polymorphs, supporting a reliable interpretation of the PXRD results. This work shows a key advantage in understanding the crystallization behaviour which can be employed for the nucleation of <span>d</span>-mannitol polymorphs without any external additives within the solution.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128353"},"PeriodicalIF":2.0,"publicationDate":"2025-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145236159","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 : 2025-10-01DOI: 10.1016/j.jcrysgro.2025.128351
Alexey S.T. Rybakov, Vu Anton Lie, Louis Mirecki, Jörg August Becker
Rutile GeO2 nanoneedles were grown using a method involving eutectics of the Ge-GeO2 system and chemical transport reactions. The synthesis was carried out at 1095–1215 K in a miniature cell, which is evacuated and sealed, enclosing all products that are generated in reactions. In this cell, one can observe the processes throughout all stages of the method in situ via video microscopy. Differences in the process development depending on the heating time and mass ratio of reagents were revealed. Depending on the latter condition, two ways for growing nanoneedles have been proposed. The needles and other reaction products were studied ex situ using SEM, dark-field and bright-field TEM, HRTEM, SAED, EDX and Raman spectroscopy. The nanoneedles are single crystals without any amorphous surface layer. They are rutile GeO2 and belong to the tetragonal crystal system. Their longitudinal growth direction is . The spacings between lattice planes in the longitudinal and lateral directions are found to be 2.8 Å and 3.2 Å respectively. At higher temperatures, larger micrometre-sized crystals of rutile GeO2 with various morphologies are formed.
{"title":"Growth of rutile GeO2 nanoneedles supported by in situ microscopy","authors":"Alexey S.T. Rybakov, Vu Anton Lie, Louis Mirecki, Jörg August Becker","doi":"10.1016/j.jcrysgro.2025.128351","DOIUrl":"10.1016/j.jcrysgro.2025.128351","url":null,"abstract":"<div><div>Rutile GeO<sub>2</sub> nanoneedles were grown using a method involving eutectics of the Ge-GeO<sub>2</sub> system and chemical transport reactions. The synthesis was carried out at 1095–1215 K in a miniature cell, which is evacuated and sealed, enclosing all products that are generated in reactions. In this cell, one can observe the processes throughout all stages of the method in situ via video microscopy. Differences in the process development depending on the heating time and mass ratio of reagents were revealed. Depending on the latter condition, two ways for growing nanoneedles have been proposed. The needles and other reaction products were studied ex situ using SEM, dark-field and bright-field TEM, HRTEM, SAED, EDX and Raman spectroscopy. The nanoneedles are single crystals without any amorphous surface layer. They are rutile GeO<sub>2</sub> and belong to the tetragonal crystal system. Their longitudinal growth direction is <span><math><mrow><mfenced><mrow><mn>001</mn></mrow></mfenced></mrow></math></span>. The spacings between lattice planes in the longitudinal and lateral directions are found to be 2.8 Å and 3.2 Å respectively. At higher temperatures, larger micrometre-sized crystals of rutile GeO<sub>2</sub> with various morphologies are formed.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128351"},"PeriodicalIF":2.0,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145236183","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}
The growth of high-quality AlN films by Metal Nitride Vapor Phase Epitaxy (MNVPE) is often limited by non-uniform reactant distribution and unstable flow fields near the substrate surface. In this work, we find that different angle between the gas flow and the substrate surface can effectively influence both the crystalline quality and surface morphology of thick AlN films grown on sapphire. Computational fluid dynamics (CFD) simulations confirmed that the small-angle conicaler substrate holder improves the premixing uniformity of Al vapor and N2, while stabilizing the gas flow above the substrate. Experimental results show that, compared to the large-angle case, the full width at half maximum (FWHM) of the (0002) and (101 ̅2) X-ray rocking curves was significantly reduced from 849 to 458 arcsec and from 935 to 565 arcsec, respectively. The surface roughness (RMS) reached 2.65 nm, and the growth rate increased from 5 to 15 μm/h. Growth evolution analysis revealed a c-axis-oriented island coalescence mechanism. These results demonstrate that adjusting the flow–substrate angle is a simple yet effective approach to significantly enhance the MNVPE growth of AlN films.Key words: MNVPE AlN Single crystal growth.
{"title":"Effect of flow–substrate angle on the growth quality of AlN films in a horizontal MNVPE reactor","authors":"Yifan Li , Tengyu Zhang , Hui Zhang , Nan Gao , Xinjian Xie , Lifeng Bian , Yulong Fang , Guifeng Chen","doi":"10.1016/j.jcrysgro.2025.128352","DOIUrl":"10.1016/j.jcrysgro.2025.128352","url":null,"abstract":"<div><div>The growth of high-quality AlN films by Metal Nitride Vapor Phase Epitaxy (MNVPE) is often limited by non-uniform reactant distribution and unstable flow fields near the substrate surface. In this work, we find that different angle between the gas flow and the substrate surface can effectively influence both the crystalline quality and surface morphology of thick AlN films grown on sapphire. Computational fluid dynamics (CFD) simulations confirmed that the small-angle conicaler substrate holder improves the premixing uniformity of Al vapor and N<sub>2</sub>, while stabilizing the gas flow above the substrate. Experimental results show that, compared to the large-angle case, the full width at half maximum (FWHM) of the (0002) and (101 ̅2) X-ray rocking curves was significantly reduced from 849 to 458 arcsec and from 935 to 565 arcsec, respectively. The surface roughness (RMS) reached 2.65 nm, and the growth rate increased from 5 to 15 μm/h. Growth evolution analysis revealed a c-axis-oriented island coalescence mechanism. These results demonstrate that adjusting the flow–substrate angle is a simple yet effective approach to significantly enhance the MNVPE growth of AlN films.Key words: MNVPE AlN Single crystal growth.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"670 ","pages":"Article 128352"},"PeriodicalIF":2.0,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217146","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 : 2025-09-27DOI: 10.1016/j.jcrysgro.2025.128349
Sukjune Choi , Chel-Jong Choi , Do Young Noh , Hyon Chol Kang
In this study, synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods were combined to identify polymorphs in SnO2 thin films deposited on sapphire (0001) substrates using radio-frequency powder sputtering. A wide range of off-specular Bragg peaks—including higher-order reflections—were examined via high-resolution, in-plane XRD analyses for precise phase identification. Evidently, the orthorhombic columbite (C-SnO2) and tetragonal rutile (R-SnO2) phases coexisted in the as-deposited films. Because both the phases were aligned with their (200) planes along the surface normal, their out-of-plane Qz components appeared nearly identical. However, the in-plane Qx and Qy components were distinguishable. The lattice constants were estimated from the in-plane Bragg peak positions, and the corresponding strain states in ultrathin films (<10 nm) were determined. In the early stage of growth, the C-SnO2 and R-SnO2 domains exhibited opposing strains—compressive and tensile strains, respectively—because of extended domain matching epitaxy, which accommodated lattice mismatch and governed the stabilization of each polymorph. The coexistence of the two phases at the atomic scale was further supported by cross-sectional high-resolution TEM analysis. These findings provide new insights into the strain-driven stabilization of polymorphs and the structural evolution of epitaxial SnO2 thin films on symmetry-mismatched substrates.
{"title":"Identification of polymorphs in epitaxial SnO2 thin films deposited on sapphire (0001) substrates","authors":"Sukjune Choi , Chel-Jong Choi , Do Young Noh , Hyon Chol Kang","doi":"10.1016/j.jcrysgro.2025.128349","DOIUrl":"10.1016/j.jcrysgro.2025.128349","url":null,"abstract":"<div><div>In this study, synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods were combined to identify polymorphs in SnO<sub>2</sub> thin films deposited on sapphire (0001) substrates using radio-frequency powder sputtering. A wide range of off-specular Bragg peaks—including higher-order reflections—were examined via high-resolution, in-plane XRD analyses for precise phase identification. Evidently, the orthorhombic columbite (C-SnO<sub>2</sub>) and tetragonal rutile (R-SnO<sub>2</sub>) phases coexisted in the as-deposited films. Because both the phases were aligned with their (200) planes along the surface normal, their out-of-plane Q<sub>z</sub> components appeared nearly identical. However, the in-plane Q<sub>x</sub> and Q<sub>y</sub> components were distinguishable. The lattice constants were estimated from the in-plane Bragg peak positions, and the corresponding strain states in ultrathin films (<10 nm) were determined. In the early stage of growth, the C-SnO<sub>2</sub> and R-SnO<sub>2</sub> domains exhibited opposing strains—compressive and tensile strains, respectively—because of extended domain matching epitaxy, which accommodated lattice mismatch and governed the stabilization of each polymorph. The coexistence of the two phases at the atomic scale was further supported by cross-sectional high-resolution TEM analysis. These findings provide new insights into the strain-driven stabilization of polymorphs and the structural evolution of epitaxial SnO<sub>2</sub> thin films on symmetry-mismatched substrates.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"670 ","pages":"Article 128349"},"PeriodicalIF":2.0,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145217079","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}
Numerical simulations are performed to understand the mass transfer in point-seed-oriented and partial shape-restricted growth of potassium dihydrogen phosphate (KDP) crystals. A type-II cut point-seed is positioned in between two parallel and rotating platforms separated by a fixed distance. Numerical simulations show that the periodic rotational motion of the two adjacent parallel platforms can lead to significant differences in surface supersaturation across the same prismatic face. The non-steady and non-laminate flow result in defects such as growth avoids and inclusions that seriously affect the optical properties of the crystal. In some cases, it results in the failure of the growth (i.e., significant cracks). Lack of surface supersaturation homogeneity results in significant difference in step-motion rates and in the step-slope, which further cause step bending and even the formation of macroscopic steps. Inclusions and avoids are often filled with solution trapped in gaps between macroscopic steps. We have found both experimentally and numerically that increasing the separation between the two parallel platforms to above 30 mm can significantly mitigate the supersaturation gradient on the crystal surface and drastically reduce the number of inclusion defects.
{"title":"Point-seed-oriented and partial shape-restricted growth of KDP crystals: Numerical simulation and experimental study","authors":"Jiezhao Lv , Peng Sun , Dexiao Fang , Changfeng Fang , Xian Zhao","doi":"10.1016/j.jcrysgro.2025.128347","DOIUrl":"10.1016/j.jcrysgro.2025.128347","url":null,"abstract":"<div><div>Numerical simulations are performed to understand the mass transfer in point-seed-oriented and partial shape-restricted growth of potassium dihydrogen phosphate (KDP) crystals. A type-II cut point-seed is positioned in between two parallel and rotating platforms separated by a fixed distance. Numerical simulations show that the periodic rotational motion of the two adjacent parallel platforms can lead to significant differences in surface supersaturation across the same prismatic face. The non-steady and non-laminate flow result in defects such as growth avoids and inclusions that seriously affect the optical properties of the crystal. In some cases, it results in the failure of the growth (i.e., significant cracks). Lack of surface supersaturation homogeneity results in significant difference in step-motion rates and in the step-slope, which further cause step bending and even the formation of macroscopic steps. Inclusions and avoids are often filled with solution trapped in gaps between macroscopic steps. We have found both experimentally and numerically that increasing the separation between the two parallel platforms to above 30 mm can significantly mitigate the supersaturation gradient on the crystal surface and drastically reduce the number of inclusion defects.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"670 ","pages":"Article 128347"},"PeriodicalIF":2.0,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155664","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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