Y. Harada, M. Ishikawa, Y. Kuroda, M. Matsukawa, D. Koyama
Modulation of the refractive index in a medium by external stimuli enables fast and reversible control of light propagation. This technology for controlling light has led to new discoveries in a wide range of research fields from physics to life sciences and has played a major role in the development of photonics devices. In this article, we focus on ultrasound as an external stimulus and have devised a method to control the refractive index of a medium using ultrasound. Our research group has previously discovered that a giant refractive-index gradient (Δn on the order of 10−2) was induced when water was irradiated with high-frequency (100 MHz range), high-intensity (on the order of MPa) ultrasound. Here, we report ray-tracing simulations in a medium with a refractive-index gradient induced by ultrasonic radiation. A numerical model of the refractive-index gradient was developed based on the experimental data, and ray-tracing simulations were performed using the Euler–Lagrange equation. The ray-tracing simulation results were close numerically to the profiles of the laser beam observed in the experiment when the laser beam was incident on the refractive-index-gradient medium.
{"title":"Simulation of light propagation in medium with an ultrasonically induced refractive index gradient","authors":"Y. Harada, M. Ishikawa, Y. Kuroda, M. Matsukawa, D. Koyama","doi":"10.1063/5.0207446","DOIUrl":"https://doi.org/10.1063/5.0207446","url":null,"abstract":"Modulation of the refractive index in a medium by external stimuli enables fast and reversible control of light propagation. This technology for controlling light has led to new discoveries in a wide range of research fields from physics to life sciences and has played a major role in the development of photonics devices. In this article, we focus on ultrasound as an external stimulus and have devised a method to control the refractive index of a medium using ultrasound. Our research group has previously discovered that a giant refractive-index gradient (Δn on the order of 10−2) was induced when water was irradiated with high-frequency (100 MHz range), high-intensity (on the order of MPa) ultrasound. Here, we report ray-tracing simulations in a medium with a refractive-index gradient induced by ultrasonic radiation. A numerical model of the refractive-index gradient was developed based on the experimental data, and ray-tracing simulations were performed using the Euler–Lagrange equation. The ray-tracing simulation results were close numerically to the profiles of the laser beam observed in the experiment when the laser beam was incident on the refractive-index-gradient medium.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140977245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mingyang Tang, Xin Liu, Yike Wang, Xiaodan Ren, Zheng Yang, Zhuo Xu, Liwei D. Geng, Yongke Yan
[001]-textured 0.4P(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3-0.5%MnO2 (Mn-PMN-PZT) ceramics were fabricated by templated grain growth using 2 vol. % BaTiO3 in this paper. Full matrices of dielectric (ɛij), elastic (sij, cij), and piezoelectric (dij) parameters were obtained by the resonance–antiresonance method. The dielectric constant ɛ33T of textured ceramics reaches 2600, which is four times that of random ceramics. Textured Mn-PMN-PZT ceramics exhibit high d33 = 984 pC/N and high k33 = 0.89, which is much larger than d33 = 223 pC/N and k33 = 0.70 of random ceramics. However, ɛ11T of ceramics decreases by about 30% after texturing, and the corresponding shear coupling coefficient k15 also decreases from 0.66 to 0.44, which may be due to the reduction in the angle between spontaneous polarization and transverse direction. Furthermore, the temperature stability of the textured ceramics was evaluated as well. The phase transition temperature TR−T was determined by the impedance method to be 120 °C. The textured Mn-PMN-PZT ceramic shows high temperature stability, which is better than PMN-PT.
{"title":"Dielectric, elastic, and piezoelectric matrices of [001]-textured Mn-PMN-PZT ceramics","authors":"Mingyang Tang, Xin Liu, Yike Wang, Xiaodan Ren, Zheng Yang, Zhuo Xu, Liwei D. Geng, Yongke Yan","doi":"10.1063/5.0212073","DOIUrl":"https://doi.org/10.1063/5.0212073","url":null,"abstract":"[001]-textured 0.4P(Mg1/3Nb2/3)O3-0.25PbZrO3-0.35PbTiO3-0.5%MnO2 (Mn-PMN-PZT) ceramics were fabricated by templated grain growth using 2 vol. % BaTiO3 in this paper. Full matrices of dielectric (ɛij), elastic (sij, cij), and piezoelectric (dij) parameters were obtained by the resonance–antiresonance method. The dielectric constant ɛ33T of textured ceramics reaches 2600, which is four times that of random ceramics. Textured Mn-PMN-PZT ceramics exhibit high d33 = 984 pC/N and high k33 = 0.89, which is much larger than d33 = 223 pC/N and k33 = 0.70 of random ceramics. However, ɛ11T of ceramics decreases by about 30% after texturing, and the corresponding shear coupling coefficient k15 also decreases from 0.66 to 0.44, which may be due to the reduction in the angle between spontaneous polarization and transverse direction. Furthermore, the temperature stability of the textured ceramics was evaluated as well. The phase transition temperature TR−T was determined by the impedance method to be 120 °C. The textured Mn-PMN-PZT ceramic shows high temperature stability, which is better than PMN-PT.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140978841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. C. Silva, R. L. Silva, J. C. Moreira, W. A. Moura-Melo, A. Pereira
The Skyrmion Hall Effect (SkHE) observed in ferromagnetic and ferrimagnetic (FI) skyrmions traveling due to a spin-polarized current can be a problematic issue when it comes to technological applications. By investigating the properties of FI skyrmions in racetracks through computational simulations, we have described the nature of their movement based on the relative values of the exchange, Dzyaloshinskii–Moriya, and anisotropy coupling constants. Beyond that, using a design strategy, a magnetic channel-like nano-device is proposed in which a spin-polarized current protocol is created to successfully control the channel on which the skyrmion will travel without the adverse SkHE. Additionally, a simple adjustment in the current strength can modify the skyrmion position sideways between different parallel channels in the nanostripe.
{"title":"Channeling skyrmions: Suppressing the skyrmion Hall effect in ferrimagnetic nanostripes","authors":"R. C. Silva, R. L. Silva, J. C. Moreira, W. A. Moura-Melo, A. Pereira","doi":"10.1063/5.0206403","DOIUrl":"https://doi.org/10.1063/5.0206403","url":null,"abstract":"The Skyrmion Hall Effect (SkHE) observed in ferromagnetic and ferrimagnetic (FI) skyrmions traveling due to a spin-polarized current can be a problematic issue when it comes to technological applications. By investigating the properties of FI skyrmions in racetracks through computational simulations, we have described the nature of their movement based on the relative values of the exchange, Dzyaloshinskii–Moriya, and anisotropy coupling constants. Beyond that, using a design strategy, a magnetic channel-like nano-device is proposed in which a spin-polarized current protocol is created to successfully control the channel on which the skyrmion will travel without the adverse SkHE. Additionally, a simple adjustment in the current strength can modify the skyrmion position sideways between different parallel channels in the nanostripe.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140981064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aroon Ananchuensook, Intuon Chatratin, Anderson Janotti, T. Watcharatharapong, J. T‐Thienprasert, Adisak Boonchun, S. Jungthawan, P. Reunchan
Transparent conducting oxides with p-type conductivity hold immense potential for various electronic applications. The role of native point defects in delafossite CuMO2 (M = Al, Ga, In) as the source of p-type conductivity has been widely acknowledged. However, understanding the primary defects governing the electrical properties and devising strategies for improvement remains a critical challenge. In this study, we employ range-separated hybrid density functional calculations to elucidate the impact of acceptor defects and their interactions with hydrogen on electrical conductivity. Our findings demonstrate that hydrogen plays a pivotal role in controlling p-type conductivity in these oxides. Our investigation reveals that the interactions between hydrogen interstitial Hi and copper vacancy VCu lead to the formation of stable complexes that are electrically inactive. Considerable binding energies are observed for Hi–VCu complexes, indicating that they are highly bound complexes with low formation energy and, thus, high concentrations under both O-rich and O-poor conditions. A second hydrogen can be bound to VCu to form 2Hi–VCu complexes, which are thermodynamically stable and function as a single donor. Furthermore, hydrogen can bind with the antisite acceptor defects, CuM, forming Hi–CuM complexes. However, the lower binding energies associated with these complexes suggest likely dissociation into isolated Hi and CuM at relatively low temperatures. By shedding light on the strong influence of hydrogen passivation of acceptor defects, this study offers valuable insights into p-type conductivity in delafossite CuMO2.
具有 p 型导电性的透明导电氧化物在各种电子应用中具有巨大的潜力。作为 p 型导电性的来源，delafossite CuMO2（M = Al、Ga、In）中的原生点缺陷的作用已得到广泛认可。然而，了解支配电性能的主要缺陷并制定改进策略仍然是一项严峻的挑战。在本研究中，我们采用范围分离混合密度泛函计算来阐明受体缺陷及其与氢的相互作用对导电性的影响。我们的研究结果表明，氢在控制这些氧化物的 p 型电导率方面起着关键作用。我们的研究发现，氢间隙 Hi 与铜空位 VCu 之间的相互作用导致形成了电性不活泼的稳定复合物。我们观察到氢-VCu 复合物具有相当大的结合能，这表明它们是高度结合的复合物，具有较低的形成能，因此在富氧和贫氧条件下都具有较高的浓度。第二个氢可以与 VCu 结合，形成 2Hi-VCu 复合物，这种复合物在热力学上是稳定的，可以作为单一供体发挥作用。此外，氢还能与反异位受体缺陷 CuM 结合，形成 Hi-CuM 复合物。然而，与这些复合物相关的较低结合能表明，在相对较低的温度下，它们很可能解离成孤立的 Hi 和 CuM。这项研究揭示了氢钝化对受体缺陷的强烈影响，从而为了解 delafossite CuMO2 的 p 型导电性提供了宝贵的见解。
{"title":"Hydrogen passivation of acceptor defects in delafossite CuMO2 (M = Al, Ga, In): Insights for enhanced p-type conductivity","authors":"Aroon Ananchuensook, Intuon Chatratin, Anderson Janotti, T. Watcharatharapong, J. T‐Thienprasert, Adisak Boonchun, S. Jungthawan, P. Reunchan","doi":"10.1063/5.0201483","DOIUrl":"https://doi.org/10.1063/5.0201483","url":null,"abstract":"Transparent conducting oxides with p-type conductivity hold immense potential for various electronic applications. The role of native point defects in delafossite CuMO2 (M = Al, Ga, In) as the source of p-type conductivity has been widely acknowledged. However, understanding the primary defects governing the electrical properties and devising strategies for improvement remains a critical challenge. In this study, we employ range-separated hybrid density functional calculations to elucidate the impact of acceptor defects and their interactions with hydrogen on electrical conductivity. Our findings demonstrate that hydrogen plays a pivotal role in controlling p-type conductivity in these oxides. Our investigation reveals that the interactions between hydrogen interstitial Hi and copper vacancy VCu lead to the formation of stable complexes that are electrically inactive. Considerable binding energies are observed for Hi–VCu complexes, indicating that they are highly bound complexes with low formation energy and, thus, high concentrations under both O-rich and O-poor conditions. A second hydrogen can be bound to VCu to form 2Hi–VCu complexes, which are thermodynamically stable and function as a single donor. Furthermore, hydrogen can bind with the antisite acceptor defects, CuM, forming Hi–CuM complexes. However, the lower binding energies associated with these complexes suggest likely dissociation into isolated Hi and CuM at relatively low temperatures. By shedding light on the strong influence of hydrogen passivation of acceptor defects, this study offers valuable insights into p-type conductivity in delafossite CuMO2.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140981356","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. M. Mamun, Amar Mavinkurve, Michiel van Soestbergen, Greta Terzariol, Muhammad A. Alam
Amorphous composite polymers are widely used as insulators in microelectronics due to their high dielectric strength, mechanical robustness, and thermal stability. However, organic–inorganic composite systems suffer from undesirable performance and accelerated degradation due to leakage current (JTot). Unfortunately, the underlying mechanism of JTot and its components (e.g., ionic and electronic constituents) are inadequately understood, particularly in extreme use conditions (e.g., high humidity and temperature). In this study, we use numerical simulation and experimental JTot data (in amorphous epoxy polymer with silica fillers) to (i) unify the electrostatic model for JTot in composite polymers, (ii) illustrate that the early part of JTot (i.e., external current) is primarily due to the image charge associated with ion transport/ localization (Jion) near the metallic contacts, (iii) demonstrate that the accumulated counter-ions reduce the barrier for electronic charge injection (by band bending) and facilitate electronic injection from the metals (Jelec), and (iv) provide an algorithm for the in situ ion transport characterization of composite insulators by exploiting Jion. This work provides new insights regarding the leakage current mechanism and how it can be used as a probe into the complex transport mechanisms of the composite material.
{"title":"Leakage current as a probe into the mechanics of carrier transport in insulating composite polymers","authors":"M. M. Mamun, Amar Mavinkurve, Michiel van Soestbergen, Greta Terzariol, Muhammad A. Alam","doi":"10.1063/5.0198337","DOIUrl":"https://doi.org/10.1063/5.0198337","url":null,"abstract":"Amorphous composite polymers are widely used as insulators in microelectronics due to their high dielectric strength, mechanical robustness, and thermal stability. However, organic–inorganic composite systems suffer from undesirable performance and accelerated degradation due to leakage current (JTot). Unfortunately, the underlying mechanism of JTot and its components (e.g., ionic and electronic constituents) are inadequately understood, particularly in extreme use conditions (e.g., high humidity and temperature). In this study, we use numerical simulation and experimental JTot data (in amorphous epoxy polymer with silica fillers) to (i) unify the electrostatic model for JTot in composite polymers, (ii) illustrate that the early part of JTot (i.e., external current) is primarily due to the image charge associated with ion transport/ localization (Jion) near the metallic contacts, (iii) demonstrate that the accumulated counter-ions reduce the barrier for electronic charge injection (by band bending) and facilitate electronic injection from the metals (Jelec), and (iv) provide an algorithm for the in situ ion transport characterization of composite insulators by exploiting Jion. This work provides new insights regarding the leakage current mechanism and how it can be used as a probe into the complex transport mechanisms of the composite material.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140657657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiechao Jiang, N. Chetuya, Joseph H. Ngai, Gordon J. Grzybowski, E. Meletis, Bruce Claflin
Growth of GeSn films directly on Si substrates is desirable for integrated photonics applications since the absence of an intervening buffer layer simplifies device fabrication. Here, we analyze the microstructure of two GeSn films grown directly on (001) Si by remote plasma-enhanced chemical vapor deposition (RPECVD): a 1000 nm thick film containing 3% Sn and a 600 nm thick, 10% Sn film. Both samples consist of an epitaxial layer with nano twins below a composite layer containing nanocrystalline and amorphous. The epilayer has uniform composition, while the nanocrystalline material has higher levels of Sn than the surrounding amorphous matrix. These two layers are separated by an interface with a distinct, hilly morphology. The transition between the two layers is facilitated by formation of densely populated (111)-coupled nano twins. The 10% Sn sample exhibits a significantly thinner epilayer than the one with 3% Sn. The in-plane lattice mismatch between GeSn and Si induces a quasi-periodic misfit dislocation network along the interface. Film growth initiates at the interface through formation of an atomic-scale interlayer with reduced Sn content, followed by the higher Sn content epitaxial layer. A corrugated surface containing a high density of twins with elevated levels of Sn at the peaks begins forming at a critical thickness. Subsequent epitaxial breakdown at the peaks produces a composite containing high levels of Sn nanocrystalline embedded in lower level of Sn amorphous. The observed microstructure and film evolution provide valuable insight into the growth mechanism that can be used to tune the RPECVD process for improved film quality.
{"title":"Epitaxial twin coupled microstructure in GeSn films prepared by remote plasma enhanced chemical vapor deposition","authors":"Jiechao Jiang, N. Chetuya, Joseph H. Ngai, Gordon J. Grzybowski, E. Meletis, Bruce Claflin","doi":"10.1063/5.0189718","DOIUrl":"https://doi.org/10.1063/5.0189718","url":null,"abstract":"Growth of GeSn films directly on Si substrates is desirable for integrated photonics applications since the absence of an intervening buffer layer simplifies device fabrication. Here, we analyze the microstructure of two GeSn films grown directly on (001) Si by remote plasma-enhanced chemical vapor deposition (RPECVD): a 1000 nm thick film containing 3% Sn and a 600 nm thick, 10% Sn film. Both samples consist of an epitaxial layer with nano twins below a composite layer containing nanocrystalline and amorphous. The epilayer has uniform composition, while the nanocrystalline material has higher levels of Sn than the surrounding amorphous matrix. These two layers are separated by an interface with a distinct, hilly morphology. The transition between the two layers is facilitated by formation of densely populated (111)-coupled nano twins. The 10% Sn sample exhibits a significantly thinner epilayer than the one with 3% Sn. The in-plane lattice mismatch between GeSn and Si induces a quasi-periodic misfit dislocation network along the interface. Film growth initiates at the interface through formation of an atomic-scale interlayer with reduced Sn content, followed by the higher Sn content epitaxial layer. A corrugated surface containing a high density of twins with elevated levels of Sn at the peaks begins forming at a critical thickness. Subsequent epitaxial breakdown at the peaks produces a composite containing high levels of Sn nanocrystalline embedded in lower level of Sn amorphous. The observed microstructure and film evolution provide valuable insight into the growth mechanism that can be used to tune the RPECVD process for improved film quality.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140658678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Angela C. Stelson, Damien Laage, Kathleen Schwarz, R. Sundararaman
{"title":"Solid-liquid interfaces: Atomic-scale structure and dynamics","authors":"Angela C. Stelson, Damien Laage, Kathleen Schwarz, R. Sundararaman","doi":"10.1063/5.0209545","DOIUrl":"https://doi.org/10.1063/5.0209545","url":null,"abstract":"","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140658521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gas gun shock experiments on cyclotrimethylenetrinitramine (RDX)-based explosive compositions that employ embedded gauge particle velocity tracers have noted a significant amount of electrical noise when compared to other explosive formulations. This paper reexamines previously published embedded gauge data on Cyclotols (60–80 wt. % RDX) to quantify the electromagnetic behavior of these materials. The primary observation is a fourfold increase in the electrical noise when Cyclotols are shocked above 4.22 ± 0.08 GPa. Electromagnetic gauge noise is also observed within particle velocity traces in reactive growth and off-Hugoniot shocks, although at higher pressures than the direct shock case, suggesting a temperature- or kinetically dependent transition. In all cases, the electrical noise disappears upon detonation. By comparing with the static high-pressure phase diagram of RDX, we interpret this change in electromagnetic behavior to be a change in the RDX crystal structure to a piezoelectric phase, although it is uncertain whether the γ or ε phase is responsible for the observed behavior.
{"title":"An exploration of anomalous electrical noise in shocked cyclotrimethylenetrinitramine (RDX)-based explosives","authors":"M. J. Burns, B. A. Chidester","doi":"10.1063/5.0191271","DOIUrl":"https://doi.org/10.1063/5.0191271","url":null,"abstract":"Gas gun shock experiments on cyclotrimethylenetrinitramine (RDX)-based explosive compositions that employ embedded gauge particle velocity tracers have noted a significant amount of electrical noise when compared to other explosive formulations. This paper reexamines previously published embedded gauge data on Cyclotols (60–80 wt. % RDX) to quantify the electromagnetic behavior of these materials. The primary observation is a fourfold increase in the electrical noise when Cyclotols are shocked above 4.22 ± 0.08 GPa. Electromagnetic gauge noise is also observed within particle velocity traces in reactive growth and off-Hugoniot shocks, although at higher pressures than the direct shock case, suggesting a temperature- or kinetically dependent transition. In all cases, the electrical noise disappears upon detonation. By comparing with the static high-pressure phase diagram of RDX, we interpret this change in electromagnetic behavior to be a change in the RDX crystal structure to a piezoelectric phase, although it is uncertain whether the γ or ε phase is responsible for the observed behavior.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140663572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fabio Isa, Javier A. Schmidt, S. Aghion, Enrico Napolitani, G. Isella, Rafael Ferragut
The concentration of vacancies and impurities in semiconductors plays a crucial role in determining their electrical, optical, and thermal properties. This study aims to clarify the nature of the interaction between positrons and ionized p-type impurities, emphasizing the similarities they share with the interaction between holes and this type of impurity. An overall strategy for investigating defects in semiconductor crystals that exhibit a combination of vacancies and p-type impurities is presented. By using positron annihilation spectroscopy, in particular, Doppler broadening of the annihilation radiation, we quantify the concentration of vacancies in epitaxial Si crystals grown by low-energy plasma-enhanced chemical vapor deposition. The vacancy number densities that we find are (1.2 ± 1.0) × 1017 cm−3 and (3.2 ± 1.5) × 1020 cm−3 for growth rates of 0.27 and 4.9 nm/s, respectively. Subsequent extended annealing of the Si samples effectively reduces the vacancy density below the sensitivity threshold of the positron technique. Secondary ion mass spectrometry indicates that the boron doping remains unaffected during the annealing treatment intended for vacancy removal. This study provides valuable insights into the intricate interplay between vacancies and ionized impurities with positrons in semiconductor crystals. The obtained results contribute to advance the control and understanding of material properties in heterostructures by emphasizing the significance of managing vacancy and dopant concentrations.
{"title":"Hole and positron interaction with vacancies and p-type dopants in epitaxially grown silicon","authors":"Fabio Isa, Javier A. Schmidt, S. Aghion, Enrico Napolitani, G. Isella, Rafael Ferragut","doi":"10.1063/5.0179101","DOIUrl":"https://doi.org/10.1063/5.0179101","url":null,"abstract":"The concentration of vacancies and impurities in semiconductors plays a crucial role in determining their electrical, optical, and thermal properties. This study aims to clarify the nature of the interaction between positrons and ionized p-type impurities, emphasizing the similarities they share with the interaction between holes and this type of impurity. An overall strategy for investigating defects in semiconductor crystals that exhibit a combination of vacancies and p-type impurities is presented. By using positron annihilation spectroscopy, in particular, Doppler broadening of the annihilation radiation, we quantify the concentration of vacancies in epitaxial Si crystals grown by low-energy plasma-enhanced chemical vapor deposition. The vacancy number densities that we find are (1.2 ± 1.0) × 1017 cm−3 and (3.2 ± 1.5) × 1020 cm−3 for growth rates of 0.27 and 4.9 nm/s, respectively. Subsequent extended annealing of the Si samples effectively reduces the vacancy density below the sensitivity threshold of the positron technique. Secondary ion mass spectrometry indicates that the boron doping remains unaffected during the annealing treatment intended for vacancy removal. This study provides valuable insights into the intricate interplay between vacancies and ionized impurities with positrons in semiconductor crystals. The obtained results contribute to advance the control and understanding of material properties in heterostructures by emphasizing the significance of managing vacancy and dopant concentrations.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140660794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thermal properties of materials are essential to many applications of thermal electronic devices. Density functional theory (DFT) has shown capability in obtaining an accurate calculation. However, the expensive computational cost limits the application of the DFT method for high-throughput screening of materials. Recently, machine learning models, especially graph neural networks (GNNs), have demonstrated high accuracy in many material properties’ prediction, such as bandgap and formation energy, but fail to accurately predict heat capacity(CV) due to the limitation in capturing crystallographic features. In our study, we have implemented the material informatics transformer (MatInFormer) framework, which has been pretrained on lattice reconstruction tasks. This approach has shown proficiency in capturing essential crystallographic features. By concatenating these features with human-designed descriptors, we achieved a mean absolute error of 4.893 and 4.505 J/(mol K) in our predictions. Our findings underscore the efficacy of the MatInFormer framework in leveraging crystallography, augmented with additional information processing capabilities.
{"title":"Multimodal learning of heat capacity based on transformers and crystallography pretraining","authors":"Hongshuo Huang, Amir Barati Farimani","doi":"10.1063/5.0201755","DOIUrl":"https://doi.org/10.1063/5.0201755","url":null,"abstract":"Thermal properties of materials are essential to many applications of thermal electronic devices. Density functional theory (DFT) has shown capability in obtaining an accurate calculation. However, the expensive computational cost limits the application of the DFT method for high-throughput screening of materials. Recently, machine learning models, especially graph neural networks (GNNs), have demonstrated high accuracy in many material properties’ prediction, such as bandgap and formation energy, but fail to accurately predict heat capacity(CV) due to the limitation in capturing crystallographic features. In our study, we have implemented the material informatics transformer (MatInFormer) framework, which has been pretrained on lattice reconstruction tasks. This approach has shown proficiency in capturing essential crystallographic features. By concatenating these features with human-designed descriptors, we achieved a mean absolute error of 4.893 and 4.505 J/(mol K) in our predictions. Our findings underscore the efficacy of the MatInFormer framework in leveraging crystallography, augmented with additional information processing capabilities.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140661204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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