Single crystals of ε-GaFeO3 were grown using the optical floating zone (OFZ) method. Two-fold symmetrical, facets appeared on the grown crystal surface towards the end of the growth process. The inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) confirmed that the growth direction was the [1 0 0] and the facet plane was the (0 0 1). We also tried to grow a ε-GaFeO3 crystal along [0 0 1] using a seed crystal. To realize the growth along [0 0 1], further optimalization of the growth conditions such as the sintering temperature of a feed rod and the growth rate of the crystal growth was necessary. The cross sections of the latter part of a crystal grown along [0 0 1] using a seed crystal were found to be (0 0 1), which was consistent with the orientation of the seed crystal. The full width at half maximum (FWHM) of the X-ray rocking curve for (002) of the latter part of the grown crystal was found to be 85.7 arcsec.
{"title":"Growth of ε-GaFeO3 bulk single crystals under controlled growth direction by optical floating zone method in high oxygen partial pressure","authors":"Yuta Takano , Yuki Maruyama , Masanori Nagao , Ryunosuke Kawamura , Satoki Shinozuka , Junji Yamanaka , Keisuke Arimoto , Satoshi Watauchi","doi":"10.1016/j.jcrysgro.2025.128377","DOIUrl":"10.1016/j.jcrysgro.2025.128377","url":null,"abstract":"<div><div>Single crystals of <em>ε</em>-GaFeO<sub>3</sub> were grown using the optical floating zone (OFZ) method. Two-fold symmetrical, facets appeared on the grown crystal surface towards the end of the growth process. The inverse pole figure (IPF) map obtained by electron backscatter diffraction (EBSD) confirmed that the growth direction was the [1 0 0] and the facet plane was the (0 0 1). We also tried to grow a <em>ε</em>-GaFeO<sub>3</sub> crystal along [0 0 1] using a seed crystal. To realize the growth along [0 0 1], further optimalization of the growth conditions such as the sintering temperature of a feed rod and the growth rate of the crystal growth was necessary. The cross sections of the latter part of a crystal grown along [0 0 1] using a seed crystal were found to be (0 0 1), which was consistent with the orientation of the seed crystal. The full width at half maximum (FWHM) of the X-ray rocking curve for (002) of the latter part of the grown crystal was found to be 85.7 arcsec.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"672 ","pages":"Article 128377"},"PeriodicalIF":2.0,"publicationDate":"2025-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414778","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 : 2025-10-22DOI: 10.1016/j.jcrysgro.2025.128376
Ning Zhang , Jonah M. Williams , Joe Oliva , Richard Becker , Aaron J. Moment
This study introduces complementary insights into in-situ observation of calcium carbonate (CaCO3) nucleation and polymorph transformation within liquid phases, employing an integrated system of Raman spectroscopy and optical microscopy imaging. This system provides insights into the process of different CaCO3 phases and their formation/transformation. The effects of different operational conditions including temperature, pH, reactant concentrations, and addition rates were investigated. Understanding is still lacking regarding the dynamic processes of the polymorphic transformations of CaCO3 in bulk solution systems with agitation, specifically the transition from the initial unstable form of amorphous calcium carbonate (ACC) to its more stable crystalline forms. This bulk system is crucial for full-scale process scale-up to produce certain properties of carbonates in various industries. The application of the Blaze Metrics probe Raman collection, integrated with a Raman spectrometer, allowed for real-time monitoring of phase formation and transformation, providing greater understanding of the kinetics and pathways involved in CaCO3 polymorph transitions. Results revealed that the nucleation and growth processes of CaCO3 are significantly influenced by supersaturation levels, base dosing methods, CO32– source, and the concentration of cations. The transformation starts from amorphous phase, to metastable vaterite and eventually to the most stable calcite under ambient, gas–liquid conditions. However, the metastable phase can be omitted under certain circumstances. Simultaneously, monitoring turbidity changes allows for the detection of dissolution, recrystallization and aggregation. This understanding is insightful for optimizing conditions in industrial processes for CO2 sequestration and the production of specific CaCO3 polymorphs for varied applications.
{"title":"In situ Raman characterization of polymorph evolution during CaCO3 precipitation in a stirred batch reactor","authors":"Ning Zhang , Jonah M. Williams , Joe Oliva , Richard Becker , Aaron J. Moment","doi":"10.1016/j.jcrysgro.2025.128376","DOIUrl":"10.1016/j.jcrysgro.2025.128376","url":null,"abstract":"<div><div>This study introduces complementary insights into in-situ observation of calcium carbonate (CaCO<sub>3</sub>) nucleation and polymorph transformation within liquid phases, employing an integrated system of Raman spectroscopy and optical microscopy imaging. This system provides insights into the process of different CaCO<sub>3</sub> phases and their formation/transformation. The effects of different operational conditions including temperature, pH, reactant concentrations, and addition rates were investigated. Understanding is still lacking regarding the dynamic processes of the polymorphic transformations of CaCO<sub>3</sub> in bulk solution systems with agitation, specifically the transition from the initial unstable form of amorphous calcium carbonate (ACC) to its more stable crystalline forms. This bulk system is crucial for full-scale process scale-up to produce certain properties of carbonates in various industries. The application of the Blaze Metrics probe Raman collection, integrated with a Raman spectrometer, allowed for real-time monitoring of phase formation and transformation, providing greater understanding of the kinetics and pathways involved in CaCO<sub>3</sub> polymorph transitions. Results revealed that the nucleation and growth processes of CaCO<sub>3</sub> are significantly influenced by supersaturation levels, base dosing methods, CO<sub>3</sub><sup>2–</sup> source, and the concentration of cations. The transformation starts from amorphous phase, to metastable vaterite and eventually to the most stable calcite under ambient, gas–liquid conditions. However, the metastable phase can be omitted under certain circumstances. Simultaneously, monitoring turbidity changes allows for the detection of dissolution, recrystallization and aggregation. This understanding is insightful for optimizing conditions in industrial processes for CO<sub>2</sub> sequestration and the production of specific CaCO<sub>3</sub> polymorphs for varied applications.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"672 ","pages":"Article 128376"},"PeriodicalIF":2.0,"publicationDate":"2025-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414777","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 : 2025-10-21DOI: 10.1016/j.jcrysgro.2025.128374
Biao Meng , Changshuai Yin , Taiqiao Liu , Yao Lu , Yujie Yan , Yang Cao , Hao Fu , Gai Wu , Kang Liang , Sheng Liu , Zhaofu Zhang
Co-designed optimization and analysis of thermal field structure and defect formation for high quality β-Ga2O3 single crystal with ultra-wide bandgap has been systematically investigated via edge-defined film-fed growth technique and numerical simulation. To confirm the wafer-scale quality, a collaborative verification scheme is developed at both microscopic and macroscopic scales. The narrow full width at half-maximum (139.82 arcsec) and low average defect density (5.5 × 104 cm−2) highlight the high quality of the bulk crystal. The overall low defect density in the crystal is confirmed through rotated electron spin resonance owing to the appearance of angle-independent single peak. The dopant of Zr is verified as the main impurity and the role of Zr, an effective n-type dopant, is investigated by first principles calculation. Moreover, the microscopic mechanism of defect formation is interpreted as atomic arrangement disorder and lattice distortion. This study presents novel proposals and strategies for the advanced improvement and optimization of β-Ga2O3 single crystal growth and defect characterization.
{"title":"Systematic characterization and defect analysis of β-Ga2O3 single crystals co-designed by the edge-defined film-fed growth method and numerical analysis","authors":"Biao Meng , Changshuai Yin , Taiqiao Liu , Yao Lu , Yujie Yan , Yang Cao , Hao Fu , Gai Wu , Kang Liang , Sheng Liu , Zhaofu Zhang","doi":"10.1016/j.jcrysgro.2025.128374","DOIUrl":"10.1016/j.jcrysgro.2025.128374","url":null,"abstract":"<div><div>Co-designed optimization and analysis of thermal field structure and defect formation for high quality <em>β</em>-Ga<sub>2</sub>O<sub>3</sub> single crystal with ultra-wide bandgap has been systematically investigated via edge-defined film-fed growth technique and numerical simulation. To confirm the wafer-scale quality, a collaborative verification scheme is developed at both microscopic and macroscopic scales. The narrow full width at half-maximum (139.82 arcsec) and low average defect density (5.5 × 10<sup>4</sup> cm<sup>−2</sup>) highlight the high quality of the bulk crystal. The overall low defect density in the crystal is confirmed through rotated electron spin resonance owing to the appearance of angle-independent single peak. The dopant of Zr is verified as the main impurity and the role of Zr, an effective n-type dopant, is investigated by first principles calculation. Moreover, the microscopic mechanism of defect formation is interpreted as atomic arrangement disorder and lattice distortion. This study presents novel proposals and strategies for the advanced improvement and optimization of <em>β</em>-Ga<sub>2</sub>O<sub>3</sub> single crystal growth and defect characterization.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"672 ","pages":"Article 128374"},"PeriodicalIF":2.0,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340022","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 : 2025-10-20DOI: 10.1016/j.jcrysgro.2025.128375
Seongho Kang , Yukyeong Cha , Kyu-Yeon Shim , Eojin-Gyere Ham, Dohoon Kim, Dongjin Byun
Gallium nitride (GaN)-based micro-light-emitting diodes (LEDs) have attracted attention as next-generation display devices owing to their low-power and long-life characteristics. In particular, through selective-area growth (SAG) of core–shell structures, m-plane light emission and quantum-confined Stark effect mitigation can be achieved simultaneously. The realization of such structures requires a precise SAG process and an efficient liftoff technique. In this study, a maskless chromium nitride (CrN) dot-patterned substrate was fabricated to implement a selective GaN growth process, and the effect of the initial low-temperature GaN (LT-GaN) layer on SAG was systematically analyzed. By evaluating the surface properties at each growth stage, it was confirmed that the CrN dot region maintained a high-polarity component and surface energy and provided favorable conditions for the selective nucleation of GaN precursors. This is attributed to selective GaN growth exclusively on the CrN dots, resulting from the combined effect of LT-GaN particle reorganization and the surface thermodynamic properties of CrN. This study is experimentally demonstrated for the feasibility of mask-free III-nitride selection growth technology, which can be used as a core technology for future micro-LED processes.
{"title":"Mask-free selective GaN growth driven by LT-GaN redistribution on patterned CrN buffers","authors":"Seongho Kang , Yukyeong Cha , Kyu-Yeon Shim , Eojin-Gyere Ham, Dohoon Kim, Dongjin Byun","doi":"10.1016/j.jcrysgro.2025.128375","DOIUrl":"10.1016/j.jcrysgro.2025.128375","url":null,"abstract":"<div><div>Gallium nitride (GaN)-based micro-light-emitting diodes (LEDs) have attracted attention as next-generation display devices owing to their low-power and long-life characteristics. In particular, through selective-area growth (SAG) of core–shell structures, m-plane light emission and quantum-confined Stark effect mitigation can be achieved simultaneously. The realization of such structures requires a precise SAG process and an efficient liftoff technique. In this study, a maskless chromium nitride (CrN) dot-patterned substrate was fabricated to implement a selective GaN growth process, and the effect of the initial low-temperature GaN (LT-GaN) layer on SAG was systematically analyzed. By evaluating the surface properties at each growth stage, it was confirmed that the CrN dot region maintained a high-polarity component and surface energy and provided favorable conditions for the selective nucleation of GaN precursors. This is attributed to selective GaN growth exclusively on the CrN dots, resulting from the combined effect of LT-GaN particle reorganization and the surface thermodynamic properties of CrN. This study is experimentally demonstrated for the feasibility of mask-free III-nitride selection growth technology, which can be used as a core technology for future micro-LED processes.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"672 ","pages":"Article 128375"},"PeriodicalIF":2.0,"publicationDate":"2025-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145414776","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 : 2025-10-19DOI: 10.1016/j.jcrysgro.2025.128370
Kohei Shima, Haruto Tsujitani, Shigefusa F. Chichibu
sp2-bonded BN films exhibiting deep-ultraviolet luminescence peaks were grown by metalorganic chemical vapor deposition using tris(dimethylamino)borane [TDMAB, B[N(CH3)2]3] and NH3 as B and N sources, respectively. BN films with thicknesses ranging from 0.7 to 6.1 µm were grown at temperatures () between 1200 and 1500 °C, under mass-transport-limited growth conditions. The results of x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman-scattering spectroscopy, and x-ray photoelectron spectroscopy confirmed the dominance of turbostratic BN and the presence of partially ordered structures such as ABC-stacked rhombohedral phases, along with minor contributions from B-O and C-N bonds. The films exhibited broad cathodoluminescence bands centered at 5.5 eV, 4.1 eV, and 3.2 eV, which are attributable to stacking defects, most probably C impurities, and possibly O impurities, respectively. One of the samples exhibited distinct zero-phonon lines at 4.14 and 4.16 eV attributable to C dimer defects in ABC-stacked (rhombohedral) and AB-stacked (Bernal) BN phases, respectively. Compared with a reference BN epilayer grown using the BCl3-NH3-N2 gas system, B[N(CH3)2]3-grown films exhibited approximately twofold higher cathodoluminescence intensities in the 5.2–6.1 eV range at 300 K, likely due to the reduced incorporation of nonradiative recombination centers. The cathodoluminescence intensity was maximized at = 1400 °C, while both higher and lower resulted in higher concentrations of nonradiative recombination centers, likely associated with C-N bonds and divacancies comprising a B-vacancy and a N-vacancy, VBVN, respectively. These results demonstrate that B[N(CH3)2]3 is a suitable B source for the deposition of luminescent BN films, offering the potential for improved deep-ultraviolet emitter performance through reduced impurity incorporation.
{"title":"Deep-ultraviolet luminescence from sp2-bonded BN films grown by metalorganic chemical vapor deposition using tris(dimethylamino)borane","authors":"Kohei Shima, Haruto Tsujitani, Shigefusa F. Chichibu","doi":"10.1016/j.jcrysgro.2025.128370","DOIUrl":"10.1016/j.jcrysgro.2025.128370","url":null,"abstract":"<div><div><em>sp</em><sup>2</sup>-bonded BN films exhibiting deep-ultraviolet luminescence peaks were grown by metalorganic chemical vapor deposition using tris(dimethylamino)borane [TDMAB, B[N(CH<sub>3</sub>)<sub>2</sub>]<sub>3</sub>] and NH<sub>3</sub> as B and N sources, respectively. BN films with thicknesses ranging from 0.7 to 6.1 µm were grown at temperatures (<span><math><mrow><msub><mi>T</mi><mi>g</mi></msub></mrow></math></span>) between 1200 and 1500 °C, under mass-transport-limited growth conditions. The results of x-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman-scattering spectroscopy, and x-ray photoelectron spectroscopy confirmed the dominance of turbostratic BN and the presence of partially ordered structures such as ABC-stacked rhombohedral phases, along with minor contributions from B-O and C-N bonds. The films exhibited broad cathodoluminescence bands centered at 5.5 eV, 4.1 eV, and 3.2 eV, which are attributable to stacking defects, most probably C impurities, and possibly O impurities, respectively. One of the samples exhibited distinct zero-phonon lines at 4.14 and 4.16 eV attributable to C dimer defects in ABC-stacked (rhombohedral) and AB-stacked (Bernal) BN phases, respectively. Compared with a reference BN epilayer grown using the BCl<sub>3</sub>-NH<sub>3</sub>-N<sub>2</sub> gas system, B[N(CH<sub>3</sub>)<sub>2</sub>]<sub>3</sub>-grown films exhibited approximately twofold higher cathodoluminescence intensities in the 5.2–6.1 eV range at 300 K, likely due to the reduced incorporation of nonradiative recombination centers. The cathodoluminescence intensity was maximized at <span><math><mrow><msub><mi>T</mi><mi>g</mi></msub></mrow></math></span> = 1400 °C, while both higher and lower <span><math><mrow><msub><mi>T</mi><mi>g</mi></msub></mrow></math></span> resulted in higher concentrations of nonradiative recombination centers, likely associated with C-N bonds and divacancies comprising a B-vacancy and a N-vacancy, V<sub>B</sub>V<sub>N</sub>, respectively. These results demonstrate that B[N(CH<sub>3</sub>)<sub>2</sub>]<sub>3</sub> is a suitable B source for the deposition of luminescent BN films, offering the potential for improved deep-ultraviolet emitter performance through reduced impurity incorporation.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"672 ","pages":"Article 128370"},"PeriodicalIF":2.0,"publicationDate":"2025-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145340021","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}
Control over nano- and microstructure of metal oxide materials is increasingly important, as it allows for fine-tuning their functionality. Material science provided a plethora of template and template-free methods to synthesize substrates with developed morphology, high crystallinity, and large specific concentration of reactive centers. Titanium phosphates (TiP), a wide group of materials composed of earth-abundant elements, are a versatile platform for the development of materials with customizable morphology and elemental composition. Ease of their synthesis and modification provided multiple sorbents, catalysts, energy capacitor electrodes and polymer additives. Elaboration of hierarchical structures in titanium phosphates beyond the regular and uniform nanocrystalline units produced substrates with a significant surplus in functionality. Although further studies in this direction seem perspective, little work was devoted to controlling features of the TiP hierarchical structure. Here, we report on a screening of general thermodynamic parameters of the hydrothermal synthesis of microspherical titanium phosphate. TiP microspheres change in size according to the Ostwald ripening mechanism with full retention of hierarchical structure. Deviations from this mechanism observed at high concentrations of phosphoric acid are explained in relation to the features of the constituting elements of the microspheres.
{"title":"Ostwald ripening behind the hierarchical structure evolution of titanium phosphate","authors":"Anton Abramian , Danil Man’ko , Valeria Zakharchenkova , Viacheslav Avdin , Oleg Bol’shakov","doi":"10.1016/j.jcrysgro.2025.128373","DOIUrl":"10.1016/j.jcrysgro.2025.128373","url":null,"abstract":"<div><div>Control over nano- and microstructure of metal oxide materials is increasingly important, as it allows for fine-tuning their functionality. Material science provided a plethora of template and template-free methods to synthesize substrates with developed morphology, high crystallinity, and large specific concentration of reactive centers. Titanium phosphates (TiP), a wide group of materials composed of earth-abundant elements, are a versatile platform for the development of materials with customizable morphology and elemental composition. Ease of their synthesis and modification provided multiple sorbents, catalysts, energy capacitor electrodes and polymer additives. Elaboration of hierarchical structures in titanium phosphates beyond the regular and uniform nanocrystalline units produced substrates with a significant surplus in functionality. Although further studies in this direction seem perspective, little work was devoted to controlling features of the TiP hierarchical structure. Here, we report on a screening of general thermodynamic parameters of the hydrothermal synthesis of microspherical titanium phosphate. TiP microspheres change in size according to the Ostwald ripening mechanism with full retention of hierarchical structure. Deviations from this mechanism observed at high concentrations of phosphoric acid are explained in relation to the features of the constituting elements of the microspheres.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128373"},"PeriodicalIF":2.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360107","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 : 2025-10-17DOI: 10.1016/j.jcrysgro.2025.128372
Arianna Jaroszynska, Petro Sadovyi, Karol Pozyczka, Michal Fijalkowski, Pawel Kempisty, Robert Kucharski, Michal Bockowski, Tomasz Sochacki
This study explores the impact of hydrogen admixture in the nitrogen carrier gas on the growth of aluminum-gallium nitride layers using halide vapor phase epitaxy. Thermodynamic modeling was used to estimate supersaturation for gallium nitride and aluminium nitride formation for different hydrogen admixtures. Simulations showed that hydrogen suppresses gallium nitride crystallization while having minimal influence on aluminum nitride. Growth experiments with 0 % and 10 % hydrogen in the carrier gas confirmed this model: aluminum content increased from 3.6 at.% to 11.4 at.% with a corresponding drop in growth rate from 13.5 μm/h to 4.5 μm/h. Additional experiments were conducted with optimized precursor flows and extended durations, ultimately resulting in the growth of a 60 μm-thick aluminum-gallium nitride layer containing 8.4 at.% aluminum content. These findings validate the simulation model and demonstrate that hydrogen can serve as an important parameter during bulk growth of aluminum gallium nitride. The process developed in this work represents a step toward the production of thick, compositionally controlled aluminum gallium nitride layers, supporting future efforts to fabricate free-standing substrates through iterative seed removal and regrowth.
{"title":"The influence of hydrogen admixture in the carrier gas on aluminum gallium nitride growth in halide vapor phase epitaxy","authors":"Arianna Jaroszynska, Petro Sadovyi, Karol Pozyczka, Michal Fijalkowski, Pawel Kempisty, Robert Kucharski, Michal Bockowski, Tomasz Sochacki","doi":"10.1016/j.jcrysgro.2025.128372","DOIUrl":"10.1016/j.jcrysgro.2025.128372","url":null,"abstract":"<div><div>This study explores the impact of hydrogen admixture in the nitrogen carrier gas on the growth of aluminum-gallium nitride layers using halide vapor phase epitaxy. Thermodynamic modeling was used to estimate supersaturation for gallium nitride and aluminium nitride formation for different hydrogen admixtures. Simulations showed that hydrogen suppresses gallium nitride crystallization while having minimal influence on aluminum nitride. Growth experiments with 0 % and 10 % hydrogen in the carrier gas confirmed this model: aluminum content increased from 3.6 at.% to 11.4 at.% with a corresponding drop in growth rate from 13.5 μm/h to 4.5 μm/h. Additional experiments were conducted with optimized precursor flows and extended durations, ultimately resulting in the growth of a 60 μm-thick aluminum-gallium nitride layer containing 8.4 at.% aluminum content. These findings validate the simulation model and demonstrate that hydrogen can serve as an important parameter during bulk growth of aluminum gallium nitride. The process developed in this work represents a step toward the production of thick, compositionally controlled aluminum gallium nitride layers, supporting future efforts to fabricate free-standing substrates through iterative seed removal and regrowth.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128372"},"PeriodicalIF":2.0,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145359658","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 : 2025-10-14DOI: 10.1016/j.jcrysgro.2025.128371
Ha Young Kang, Jaeheon Jung, Young Soo Hwang, Roy B. Chung
This study systematically explores the structural factors influencing κ-phase gallium oxide (κ-Ga2O3) thin film growth and domain formation on non-basal plane substrates. Accordingly, we grew κ-Ga2O3 thin films using mist chemical vapor deposition on both basal and non-basal plane sapphire (c-, a-, m-, and r-plane) and GaN (c- and m-plane) substrates for analysis. Crystallinity, orientation, and domain structures were assessed by X-ray diffraction including 2θ–ω scans, rocking curves, and φ-scans. On c- and a-plane sapphire and GaN substrates, κ-Ga2O3 with c-axis orientation was selectively stabilized, whereas α-Ga2O3 predominantly formed on r- and m-plane sapphire. Regardless of substrate symmetry, all κ-Ga2O3 films exhibited persistent three-fold rotational domains, highlighting the limitations of current substrate configurations. These results demonstrate the significant influence of substrate atomic arrangement on phase stability and domain control, emphasizing the need for advanced substrate engineering to realize single-domain κ-Ga2O3 thin films with improved crystalline quality.
{"title":"Influence of substrate atomic symmetry on the epitaxy and rotational domain formation of κ-Ga2O3","authors":"Ha Young Kang, Jaeheon Jung, Young Soo Hwang, Roy B. Chung","doi":"10.1016/j.jcrysgro.2025.128371","DOIUrl":"10.1016/j.jcrysgro.2025.128371","url":null,"abstract":"<div><div>This study systematically explores the structural factors influencing κ-phase gallium oxide (κ-Ga<sub>2</sub>O<sub>3</sub>) thin film growth and domain formation on non-basal plane substrates. Accordingly, we grew κ-Ga<sub>2</sub>O<sub>3</sub> thin films using mist chemical vapor deposition on both basal and non-basal plane sapphire (c-, a-, m-, and r-plane) and GaN (c- and m-plane) substrates for analysis. Crystallinity, orientation, and domain structures were assessed by X-ray diffraction including 2θ–ω scans, rocking curves, and φ-scans. On c- and a-plane sapphire and GaN substrates, κ-Ga<sub>2</sub>O<sub>3</sub> with c-axis orientation was selectively stabilized, whereas α-Ga<sub>2</sub>O<sub>3</sub> predominantly formed on r- and m-plane sapphire. Regardless of substrate symmetry, all κ-Ga<sub>2</sub>O<sub>3</sub> films exhibited persistent three-fold rotational domains, highlighting the limitations of current substrate configurations. These results demonstrate the significant influence of substrate atomic arrangement on phase stability and domain control, emphasizing the need for advanced substrate engineering to realize single-domain κ-Ga<sub>2</sub>O<sub>3</sub> thin films with improved crystalline quality.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128371"},"PeriodicalIF":2.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326237","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 : 2025-10-14DOI: 10.1016/j.jcrysgro.2025.128355
Yingzhao Geng , Yang Xu , Xu Li , Xiao Wang , Hao Wu , Chang Liu
InN thin films have been deposited on fluorophlogopite mica (F-mica) substrates by molecular beam epitaxy (MBE) under various growth conditions. The N2 flow rate and radio-frequency (RF) power were adjusted to realize N-rich and In-rich growth conditions. During the transition from N-rich to In-rich conditions, the plateaus formed by partially coalesced larger grains or islands were observed, which was attributed to the short diffusion length of indium (In) atoms. Meanwhile, the In-rich InN thin films exhibit lower dislocation densities than those of N-rich thin films. Under In-rich conditions, similar plateaus were also observed at lower growth temperatures. Additionally, the surface roughness and total dislocation density were reduced by increasing the growth and In source temperatures to 490 and 775 °C. Throughout all growth condition, the in-plane epitaxial relationship remains as InN [110]//F-mica [010].
{"title":"Molecular beam epitaxy of flexible InN thin films on fluorophlogopite mica","authors":"Yingzhao Geng , Yang Xu , Xu Li , Xiao Wang , Hao Wu , Chang Liu","doi":"10.1016/j.jcrysgro.2025.128355","DOIUrl":"10.1016/j.jcrysgro.2025.128355","url":null,"abstract":"<div><div>InN thin films have been deposited on fluorophlogopite mica (F-mica) substrates by molecular beam epitaxy (MBE) under various growth conditions. The N<sub>2</sub> flow rate and radio-frequency (RF) power were adjusted to realize N-rich and In-rich growth conditions. During the transition from N-rich to In-rich conditions, the plateaus formed by partially coalesced larger grains or islands were observed, which was attributed to the short diffusion length of indium (In) atoms. Meanwhile, the In-rich InN thin films exhibit lower dislocation densities than those of N-rich thin films. Under In-rich conditions, similar plateaus were also observed at lower growth temperatures. Additionally, the surface roughness and total dislocation density were reduced by increasing the growth and In source temperatures to 490 and 775 °C. Throughout all growth condition, the in-plane epitaxial relationship remains as InN [110]//F-mica [010].</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128355"},"PeriodicalIF":2.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326234","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 : 2025-10-14DOI: 10.1016/j.jcrysgro.2025.128369
Minh-Anh Nguyen Tran , Van Quang Nguyen , Cao Khang Nguyen , Sunglae Cho
In this work, we systematically investigate the epitaxial growth of GaSe thin films on different substrates, including GaAs(100), GaAs(111), GaN/Al2O3(0001), and SrTiO3(001), using molecular beam epitaxy (MBE). All films exhibit a universal strain configuration with biaxial tensile strain in the basal plane coupled with out-of-plane compressive strain, whose magnitude varies with substrate type. On cubic GaAs substrates, GaSe grows with well-aligned single domains, while hexagonal GaN and perovskite STO promote multiple domain orientations, reflecting the role of interfacial symmetry mismatch. X-ray diffraction confirms out-of-plane lattice contraction, with compressive strain ranging from ∼1.3 % on GaAs(1 0 0) to ∼2.5 % on GaN(0001). Raman spectroscopy shows red-shifts of the in-plane phonon mode, directly evidencing biaxial tensile strain. These findings demonstrate that substrate-induced strain, governed primarily by symmetry mismatch, provides a powerful and intrinsic route to tailor the optical and electronic properties of GaSe, enabling new strategies for strain-engineered 2D optoelectronic devices.
{"title":"Strain modulation in 2D GaSe epitaxial films by substrate engineering via molecular beam epitaxy (MBE)","authors":"Minh-Anh Nguyen Tran , Van Quang Nguyen , Cao Khang Nguyen , Sunglae Cho","doi":"10.1016/j.jcrysgro.2025.128369","DOIUrl":"10.1016/j.jcrysgro.2025.128369","url":null,"abstract":"<div><div>In this work, we systematically investigate the epitaxial growth of GaSe thin films on different substrates, including GaAs(100), GaAs(111), GaN/Al<sub>2</sub>O<sub>3</sub>(0001), and SrTiO<sub>3</sub>(001), using molecular beam epitaxy (MBE). All films exhibit a universal strain configuration with biaxial tensile strain in the basal plane coupled with out-of-plane compressive strain, whose magnitude varies with substrate type. On cubic GaAs substrates, GaSe grows with well-aligned single domains, while hexagonal GaN and perovskite STO promote multiple domain orientations, reflecting the role of interfacial symmetry mismatch. X-ray diffraction confirms out-of-plane lattice contraction, with compressive strain ranging from ∼1.3 % on GaAs(1<!--> <!-->0<!--> <!-->0) to ∼2.5 % on GaN(0001). Raman spectroscopy shows red-shifts of the in-plane <span><math><msubsup><mi>E</mi><mrow><mn>2</mn><mi>g</mi></mrow><mn>2</mn></msubsup></math></span> phonon mode, directly evidencing biaxial tensile strain. These findings demonstrate that substrate-induced strain, governed primarily by symmetry mismatch, provides a powerful and intrinsic route to tailor the optical and electronic properties of GaSe, enabling new strategies for strain-engineered 2D optoelectronic devices.</div></div>","PeriodicalId":353,"journal":{"name":"Journal of Crystal Growth","volume":"671 ","pages":"Article 128369"},"PeriodicalIF":2.0,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145326236","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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