Johannes Holler, Malte Selig, Dmitry S. Smirnov, Michael Kempf, Jonas Zipfel, Philipp Nagler, Manuel Katzer, Florian Katsch, Mariana V. Ballottin, Anatolie A. Mitioglu, Alexey Chernikov, Peter C. M. Christianen, Christian Schüller, Andreas Knorr, Tobias Korn
Transition‐metal dichalcogenide (TMD) monolayers are direct‐gap semiconductors with peculiar spin–valley coupling. Combining two different TMDs can lead to a type‐II band alignment and formation of interlayer excitons (ILE). In MoSe2–WSe2 heterobilayers, optically bright ILE are only observable if the interlayer twist angle is close to 0° (aligned, R‐type) or 60° (anti‐aligned, H‐type). Herein, low‐temperature optical spectroscopy studies of these ILE in high magnetic fields are presented. Depending on interlayer twist, ILE transitions are either valley conserving or between different valleys. This allows engineering of the ILE g factor, changing its magnitude and even its sign. Additionally, applied magnetic fields induce a valley polarization of the ILE, and its buildup can directly be observed in helicity‐ and time‐resolved photoluminescence, with peculiar features due to the dependence of ILE optical selection rules on interlayer registry. For both, R‐type and H‐type structures, it is found that at 24 Tesla, the valley polarization is resonantly enhanced, even though their g factors are markedly different. This observation hints at a scattering process involving single carriers within the ILE and zone‐boundary acoustic phonons.
过渡金属二掺杂化合物（TMD）单层是具有特殊自旋-谷耦合的直接隙半导体。将两种不同的 TMD 结合在一起可导致 II 型带排列和层间激子（ILE）的形成。在 MoSe2-WSe2 异质层中，只有当层间扭转角接近 0°（对齐，R 型）或 60°（反对齐，H 型）时，才能观察到光亮的 ILE。本文介绍了这些 ILE 在高磁场中的低温光学光谱研究。根据层间扭转的不同，ILE 转变要么是守谷转变，要么是不同谷之间的转变。这允许对 ILE g 因子进行工程设计，改变其大小甚至符号。此外，外加磁场会诱发 ILE 的谷极化，其积累可直接在激发和时间分辨光致发光中观察到，由于 ILE 光学选择规则取决于层间注册，因此具有特殊的特征。研究发现，对于 R 型和 H 型结构，在 24 特斯拉条件下，谷极化会发生共振增强，尽管它们的 g 因子明显不同。这一观察结果暗示了涉及 ILE 内单载流子和区界声子的散射过程。
{"title":"Magneto‐Spectroscopy of Interlayer Excitons in Transition‐Metal Dichalcogenide Heterostructures","authors":"Johannes Holler, Malte Selig, Dmitry S. Smirnov, Michael Kempf, Jonas Zipfel, Philipp Nagler, Manuel Katzer, Florian Katsch, Mariana V. Ballottin, Anatolie A. Mitioglu, Alexey Chernikov, Peter C. M. Christianen, Christian Schüller, Andreas Knorr, Tobias Korn","doi":"10.1002/pssb.202400079","DOIUrl":"https://doi.org/10.1002/pssb.202400079","url":null,"abstract":"Transition‐metal dichalcogenide (TMD) monolayers are direct‐gap semiconductors with peculiar spin–valley coupling. Combining two different TMDs can lead to a type‐II band alignment and formation of interlayer excitons (ILE). In MoSe<jats:sub>2</jats:sub>–WSe<jats:sub>2</jats:sub> heterobilayers, optically bright ILE are only observable if the interlayer twist angle is close to 0° (aligned, R‐type) or 60° (anti‐aligned, H‐type). Herein, low‐temperature optical spectroscopy studies of these ILE in high magnetic fields are presented. Depending on interlayer twist, ILE transitions are either valley conserving or between different valleys. This allows engineering of the ILE g factor, changing its magnitude and even its sign. Additionally, applied magnetic fields induce a valley polarization of the ILE, and its buildup can directly be observed in helicity‐ and time‐resolved photoluminescence, with peculiar features due to the dependence of ILE optical selection rules on interlayer registry. For both, R‐type and H‐type structures, it is found that at 24 Tesla, the valley polarization is resonantly enhanced, even though their g factors are markedly different. This observation hints at a scattering process involving single carriers within the ILE and zone‐boundary acoustic phonons.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"27 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141527479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The possibility of Fe loaded on BP (Fe@BP) as an efficient gas sensor for the detection of toxic gases such as NO2, NO, and CO is studied by the first‐principles calculation, and it is proposed that Fe@BP is an excellent gas‐sensitive material. The adsorption behaviors of gases on Fe@BP were analyzed in terms of adsorption configurations and electronic properties. It is found that all gases adsorbed on Fe@BP exhibit significantly enhanced interactions, and the adsorption intensity is much larger than that of molecules adsorbed on the surface of pure BP. Fe@BP has high selectivity for toxic and ambient gas molecules. In addition, the adsorption strength of NO2 and NO molecules on Fe@BP increases after compression strain is applied (within −3%), while the adsorption strength of CO decreases gradually. After the tensile strain is applied, the adsorption intensity of NO2 and NO is decreased, but that of CO is increased gradually. It is speculated that the strain causes changes in the electronic structure, which affects the adsorption behavior. The adsorption of NO has a stronger strain sensitivity. For these reasons, Fe@BP with high adsorption strength and strain selection is the ideal gas‐sensitive material.
通过第一性原理计算，研究了将铁负载在 BP（Fe@BP）上作为高效气体传感器检测二氧化氮、一氧化氮和一氧化碳等有毒气体的可能性，并提出 Fe@BP 是一种优良的气敏材料。从吸附构型和电子特性方面分析了气体在 Fe@BP 上的吸附行为。结果发现，所有吸附在 Fe@BP 上的气体都表现出明显增强的相互作用，吸附强度远大于吸附在纯 BP 表面的分子。Fe@BP 对有毒气体和环境气体分子具有很高的选择性。此外，施加压缩应变后，Fe@BP 对 NO2 和 NO 分子的吸附强度增加（-3% 以内），而对 CO 的吸附强度逐渐减小。施加拉伸应变后，二氧化氮和一氧化氮的吸附强度降低，而一氧化碳的吸附强度逐渐增加。推测应变导致电子结构发生变化，从而影响了吸附行为。对 NO 的吸附具有更强的应变敏感性。因此，具有高吸附强度和应变选择性的 Fe@BP 是理想的气敏材料。
{"title":"Strain‐Induced Selective Active Gas Sensor Based on Fe‐Loaded Black Phosphorus","authors":"Zongyu Huang, Xi Chen, Chaobo Luo, Shenrui Zhang, Yongxiang Cui, Gencai Guo, Jianxin Zhong, Xiang Qi","doi":"10.1002/pssb.202400011","DOIUrl":"https://doi.org/10.1002/pssb.202400011","url":null,"abstract":"The possibility of Fe loaded on BP (Fe@BP) as an efficient gas sensor for the detection of toxic gases such as NO<jats:sub>2</jats:sub>, NO, and CO is studied by the first‐principles calculation, and it is proposed that Fe@BP is an excellent gas‐sensitive material. The adsorption behaviors of gases on Fe@BP were analyzed in terms of adsorption configurations and electronic properties. It is found that all gases adsorbed on Fe@BP exhibit significantly enhanced interactions, and the adsorption intensity is much larger than that of molecules adsorbed on the surface of pure BP. Fe@BP has high selectivity for toxic and ambient gas molecules. In addition, the adsorption strength of NO<jats:sub>2</jats:sub> and NO molecules on Fe@BP increases after compression strain is applied (within −3%), while the adsorption strength of CO decreases gradually. After the tensile strain is applied, the adsorption intensity of NO<jats:sub>2</jats:sub> and NO is decreased, but that of CO is increased gradually. It is speculated that the strain causes changes in the electronic structure, which affects the adsorption behavior. The adsorption of NO has a stronger strain sensitivity. For these reasons, Fe@BP with high adsorption strength and strain selection is the ideal gas‐sensitive material.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"43 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141527480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Selective area growth and epitaxial lateral overgrowth (ELOG) of semipolar (101) GaN stripes are demonstrated on a trench patterned vicinal (001) Si substrate fabricated by a maskless photolithography‐based process. High precision alignment enables selective mask formation to one sidewall of the trench. Selective area growth of GaN stripes is conducted from the (111) plane sidewall of Si, and ELOG region reaches ≈13 μm. The ELOG GaN crystal is dislocation‐free at most areas. The semipolar GaN stripes with atomically flat surface morphology are uniformly obtained. Light‐emitting diode structures with InGaN/GaN multiple quantum wells are grown on the 13‐μm ELOG (101) GaN stripes and a single photoluminescence emission peaked at 485 nm is obtained, suggesting potential for the cost‐effective semipolar micro light‐emitting diode fabrication technologies.
在采用无掩模光刻工艺制造的沟槽图案沧桑（001）硅衬底上，演示了半极性（101）氮化镓条带的选择性面积生长和外延横向过度生长（ELOG）。通过高精度对准，可以在沟槽的一侧壁上选择性地形成掩膜。氮化镓条纹从硅的（111）平面侧壁开始选择性区域生长，ELOG 区域达到 ≈13 μm。ELOG GaN 晶体的大部分区域都没有位错。得到的半极性氮化镓条带具有均匀的原子平整表面形态。在 13 μm 的 ELOG (101) GaN 带上生长出了具有 InGaN/GaN 多量子阱的发光二极管结构，并获得了峰值为 485 nm 的单一光致发光，这表明具有成本效益的半极性微型发光二极管制造技术具有潜力。
{"title":"Large Area Epitaxial Lateral Overgrowth of Semipolar (11¯$1 left(right. macr left.right)$01) GaN Stripes on Patterned Si Substrates Prepared using Maskless Lithography","authors":"Naofumi Takeda, Masahiro Uemukai, Tomoyuki Tanikawa, Ryuji Katayama","doi":"10.1002/pssb.202400071","DOIUrl":"https://doi.org/10.1002/pssb.202400071","url":null,"abstract":"Selective area growth and epitaxial lateral overgrowth (ELOG) of semipolar (101) GaN stripes are demonstrated on a trench patterned vicinal (001) Si substrate fabricated by a maskless photolithography‐based process. High precision alignment enables selective mask formation to one sidewall of the trench. Selective area growth of GaN stripes is conducted from the (111) plane sidewall of Si, and ELOG region reaches ≈13 μm. The ELOG GaN crystal is dislocation‐free at most areas. The semipolar GaN stripes with atomically flat surface morphology are uniformly obtained. Light‐emitting diode structures with InGaN/GaN multiple quantum wells are grown on the 13‐μm ELOG (101) GaN stripes and a single photoluminescence emission peaked at 485 nm is obtained, suggesting potential for the cost‐effective semipolar micro light‐emitting diode fabrication technologies.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"46 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141532286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Herein, analytical modeling of Fe3O4/x(≈1.1 nm)/Co (x = rubrene, C60, and bathocuproine (BCP)) magnetic tunnel junctions (MTJs) has been performed using rubrene, C60, and BCP as organic spacer layers. The simulation is considered as nonequilibrium Green's function assuming spin precession at ferromagnet/organic semiconductor (FM/OSC) interface defect states. The voltage‐dependent resistances for both parallel (RP) and antiparallel (RAP) orientations have been observed to be dependent on spin injection from FM/OSC defect states. Pinning well‐dependent defect state depths have been associated with band misalignment‐induced lattice distortion at FM/OSC interface of the devices. The large tunnel magnetoresistance (TMR) response for rubrene‐based MTJ device has been attributed to a higher change of FM/OSC defect state depths with voltage. High TMR may have reduced spin torque‐dependent spin precession, leading to lower spin transfer torque for the rubrene device. Hence, engineering of defect states at the FM/OSC interface may lead to the successful realization of enhanced TMR in organic spacer MTJs for high‐performance spintronic memory applications.
{"title":"Effect of Ferromagnet/Organic Semiconductor Interface Defect States on Tunnel Magnetoresistance of Hybrid Magnetic Tunnel Junctions","authors":"Yadlapalli Sujatha, Abhishek Pahuja, Debajit Deb","doi":"10.1002/pssb.202400059","DOIUrl":"https://doi.org/10.1002/pssb.202400059","url":null,"abstract":"Herein, analytical modeling of Fe<jats:sub>3</jats:sub>O<jats:sub>4</jats:sub>/<jats:italic>x</jats:italic>(≈1.1 nm)/Co (<jats:italic>x</jats:italic> = rubrene, C<jats:sub>60</jats:sub>, and bathocuproine (BCP)) magnetic tunnel junctions (MTJs) has been performed using rubrene, C<jats:sub>60</jats:sub>, and BCP as organic spacer layers. The simulation is considered as nonequilibrium Green's function assuming spin precession at ferromagnet/organic semiconductor (FM/OSC) interface defect states. The voltage‐dependent resistances for both parallel (<jats:italic>R</jats:italic><jats:sub>P</jats:sub>) and antiparallel (<jats:italic>R</jats:italic><jats:sub>AP</jats:sub>) orientations have been observed to be dependent on spin injection from FM/OSC defect states. Pinning well‐dependent defect state depths have been associated with band misalignment‐induced lattice distortion at FM/OSC interface of the devices. The large tunnel magnetoresistance (TMR) response for rubrene‐based MTJ device has been attributed to a higher change of FM/OSC defect state depths with voltage. High TMR may have reduced spin torque‐dependent spin precession, leading to lower spin transfer torque for the rubrene device. Hence, engineering of defect states at the FM/OSC interface may lead to the successful realization of enhanced TMR in organic spacer MTJs for high‐performance spintronic memory applications.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"14 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141527478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexandra Ibanez, Mathieu Leroux, Nikita Nikitskiy, Wilfried Desrat, Matthieu Moret, Pierre Valvin, Guillaume Cassabois, Julien Brault, Bernard Gil, Fumiya Chugenji, Kirihara Taiga, Muhamad Ajmal Khan, Hideki Hirayama
The polarized photoluminescence emitted on the edge of a series of aluminum‐rich (Al,Ga)N‐AlN quantum wells (QWs) grown by molecular beam epitaxy on AlN templates deposited by metal organic chemical vapor deposition on c‐plane sapphire is measured. The contrast and the principal axis of the emission diagrams for 2 nm‐thick (Al,Ga)N QWs grown for aluminum compositions between 40% and 90% are studied. The light is emitted on the edge of the QWs at wavelengths going from 280 nm down to 209 nm. The emission diagram, a change from oblate to prolate with respect to the in‐plane orientation, for an aluminum composition is found to occur around 72%, that is, at an emission wavelength of about 235 nm. The orientations and shapes of the edge‐emission diagrams indicate that the fluctuations of the composition of the (Al,Ga)N confining layer are deep enough for producing intravalence band mixings. This property, that acts in concert with the built‐in strain and quantum‐confined Stark effect, contributes to the anisotropy of the light emission when the aluminum composition reaches 60–70%, that is, for an emission wavelength of 260–235 nm.
{"title":"The Influence of Alloy Disorder Effects on the Anisotropy of Emission Diagrams in (Al,Ga)N Quantum Wells Embedded into AlN Barriers","authors":"Alexandra Ibanez, Mathieu Leroux, Nikita Nikitskiy, Wilfried Desrat, Matthieu Moret, Pierre Valvin, Guillaume Cassabois, Julien Brault, Bernard Gil, Fumiya Chugenji, Kirihara Taiga, Muhamad Ajmal Khan, Hideki Hirayama","doi":"10.1002/pssb.202400215","DOIUrl":"https://doi.org/10.1002/pssb.202400215","url":null,"abstract":"The polarized photoluminescence emitted on the edge of a series of aluminum‐rich (Al,Ga)N‐AlN quantum wells (QWs) grown by molecular beam epitaxy on AlN templates deposited by metal organic chemical vapor deposition on c‐plane sapphire is measured. The contrast and the principal axis of the emission diagrams for 2 nm‐thick (Al,Ga)N QWs grown for aluminum compositions between 40% and 90% are studied. The light is emitted on the edge of the QWs at wavelengths going from 280 nm down to 209 nm. The emission diagram, a change from oblate to prolate with respect to the in‐plane orientation, for an aluminum composition is found to occur around 72%, that is, at an emission wavelength of about 235 nm. The orientations and shapes of the edge‐emission diagrams indicate that the fluctuations of the composition of the (Al,Ga)N confining layer are deep enough for producing intravalence band mixings. This property, that acts in concert with the built‐in strain and quantum‐confined Stark effect, contributes to the anisotropy of the light emission when the aluminum composition reaches 60–70%, that is, for an emission wavelength of 260–235 nm.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"20 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Cu–Zr‐based metallic glasses (MGs) have recently sparked great attention due to their outstanding properties and their improved glass‐forming ability (GFA). Therefore, a molecular dynamics study is performed to investigate the effect of composition on the structural analysis methods including the radial distribution function, Voronoi analysis, and coordination number of three Cu‐Zr‐Al alloys to predict the system having the much higher GFA. The T–V curves during the cooling process involve transitioning the liquid state to the glassy state, demonstrating that and are good glass formers. The findings reveal that the splitting of the second peak in the radial distribution function at results in more pronounced one. It is also indicated that with increasing Al content, the system undergoes a decrease toward the CN. Additionally, higher Al content contributes to the higher content of the full icosahedra as well as the distorted icosahedra, consequently, higher GFA. These structures, demonstrate various modes of linkage including vertex sharing, edge sharing, face sharing, and interpenetrating sharing, resulting in more dense atomic packing. Finally, strong correlations between the atomic compositions with the structural properties are shown, which can help to predict the much higher GFA system.
{"title":"Structural Correlation of the Glass‐Forming Ability in a Cu–Zr‐Based Metallic Glass: A Molecular Dynamics Study","authors":"Meryem Kbirou, Salma Trady, Imad Achik, M'hammed Mazroui","doi":"10.1002/pssb.202400100","DOIUrl":"https://doi.org/10.1002/pssb.202400100","url":null,"abstract":"The Cu–Zr‐based metallic glasses (MGs) have recently sparked great attention due to their outstanding properties and their improved glass‐forming ability (GFA). Therefore, a molecular dynamics study is performed to investigate the effect of composition on the structural analysis methods including the radial distribution function, Voronoi analysis, and coordination number of three Cu‐Zr‐Al alloys to predict the system having the much higher GFA. The <jats:italic>T–V</jats:italic> curves during the cooling process involve transitioning the liquid state to the glassy state, demonstrating that and are good glass formers. The findings reveal that the splitting of the second peak in the radial distribution function at results in more pronounced one. It is also indicated that with increasing Al content, the system undergoes a decrease toward the CN. Additionally, higher Al content contributes to the higher content of the full icosahedra as well as the distorted icosahedra, consequently, higher GFA. These structures, demonstrate various modes of linkage including vertex sharing, edge sharing, face sharing, and interpenetrating sharing, resulting in more dense atomic packing. Finally, strong correlations between the atomic compositions with the structural properties are shown, which can help to predict the much higher GFA system.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"62 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tomoaki Kachi, Hayata Takahata, Ryunosuke Oka, Hisanori Ishiguro, Tetsuya Takeuchi, Satoshi Kamiyama, Motoaki Iwaya, Yoshiki Saito, Koji Okuno
The crack formations in AlGaN templates for deep ultraviolet (DUV) light‐emitting diodes (LEDs) are investigated and successfully suppressed. The strain values in AlGaN thick layers on sapphire substrates by in situ wafer curvature measurements and ex situ X‐ray diffraction measurements are evaluated. It is found that the tensile strain during the AlGaN thick layer growth comes from a thermal expansion difference between the AlGaN thick layer and the sapphire substrate as the temperature changes from the AlN nucleation layer growth to the AlGaN thick layer growth. When the temperature change is 100 °C and less, the tensile strain of 0.1% and less is observed during the AlGaN thick layer growth, resulting in no crack formations in the AlGaN thick layer. Furthermore, a DUV LED layer structure grown on such a crack‐free AlGaN template shows no crack formations. Thus, to suppress crack formation in templates fabricated for DUV LEDs, their growth temperature must be optimized by considering thermal expansions caused by the changes in the growth temperature from the nucleation layer to the thick layer.
研究并成功抑制了用于深紫外（DUV）发光二极管（LED）的氮化铝模板中裂纹的形成。通过原位晶片曲率测量和原位 X 射线衍射测量，评估了蓝宝石衬底上氮化铝厚层的应变值。研究发现，在氮化铝厚层生长过程中产生的拉伸应变来自氮化铝厚层和蓝宝石衬底之间的热膨胀差。当温度变化不超过 100 ℃ 时，氮化铝厚层生长过程中的拉伸应变不超过 0.1%，因此氮化铝厚层不会出现裂纹。此外，在这种无裂纹的 AlGaN 模板上生长的 DUV LED 层结构也不会出现裂纹。因此，要抑制用于制造 DUV LED 的模板中裂纹的形成，必须考虑到从成核层到厚层的生长温度变化所引起的热膨胀，从而优化其生长温度。
{"title":"Effect of Growth Temperature on Strain during Growth and Crack Suppression in AlGaN Templates on Sapphire Substrates for Deep Ultraviolet Light‐Emitting Diodes","authors":"Tomoaki Kachi, Hayata Takahata, Ryunosuke Oka, Hisanori Ishiguro, Tetsuya Takeuchi, Satoshi Kamiyama, Motoaki Iwaya, Yoshiki Saito, Koji Okuno","doi":"10.1002/pssb.202400063","DOIUrl":"https://doi.org/10.1002/pssb.202400063","url":null,"abstract":"The crack formations in AlGaN templates for deep ultraviolet (DUV) light‐emitting diodes (LEDs) are investigated and successfully suppressed. The strain values in AlGaN thick layers on sapphire substrates by in situ wafer curvature measurements and ex situ X‐ray diffraction measurements are evaluated. It is found that the tensile strain during the AlGaN thick layer growth comes from a thermal expansion difference between the AlGaN thick layer and the sapphire substrate as the temperature changes from the AlN nucleation layer growth to the AlGaN thick layer growth. When the temperature change is 100 °C and less, the tensile strain of 0.1% and less is observed during the AlGaN thick layer growth, resulting in no crack formations in the AlGaN thick layer. Furthermore, a DUV LED layer structure grown on such a crack‐free AlGaN template shows no crack formations. Thus, to suppress crack formation in templates fabricated for DUV LEDs, their growth temperature must be optimized by considering thermal expansions caused by the changes in the growth temperature from the nucleation layer to the thick layer.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"92 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article is aimed at understanding of the complex design of metalorganic chemical vapour deposition ‐grown InGaN‐based red light‐emitting diode (LED) structure. The contribution of different elements of red LED structure to the stress distribution and threading dislocation density (TDD) evolution is theoretically investigated. For this purpose a self‐consistent modeling of the structure growth process is used, taking into account stress‐modulated indium incorporation, mismatch stress relaxation by threading dislocations and V‐pits, and nucleation of new threading dislocations. The simulation results, consisting of composition, stress, and TDD profiles, are then utilized for modeling of device operation, which allows to analyze contribution of different elements to the heterostructure operation.
本文旨在了解基于金属有机化学气相沉积法生长的 InGaN 基红色发光二极管（LED）结构的复杂设计。文章从理论上研究了红光 LED 结构中不同元素对应力分布和穿线位错密度 (TDD) 演变的影响。为此，采用了结构生长过程的自洽模型，考虑了应力调制铟的加入、穿线位错和 V 型凹坑的错配应力松弛以及新穿线位错的成核。模拟结果包括成分、应力和 TDD 曲线，然后用于器件运行建模，从而分析不同元素对异质结构运行的贡献。
{"title":"Crystal Quality and Efficiency Engineering of InGaN‐Based Red Light‐Emitting Diodes","authors":"Mikhail Rudinsky, Kirill Bulashevich","doi":"10.1002/pssb.202400034","DOIUrl":"https://doi.org/10.1002/pssb.202400034","url":null,"abstract":"This article is aimed at understanding of the complex design of metalorganic chemical vapour deposition ‐grown InGaN‐based red light‐emitting diode (LED) structure. The contribution of different elements of red LED structure to the stress distribution and threading dislocation density (TDD) evolution is theoretically investigated. For this purpose a self‐consistent modeling of the structure growth process is used, taking into account stress‐modulated indium incorporation, mismatch stress relaxation by threading dislocations and V‐pits, and nucleation of new threading dislocations. The simulation results, consisting of composition, stress, and TDD profiles, are then utilized for modeling of device operation, which allows to analyze contribution of different elements to the heterostructure operation.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"68 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141196571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article theoretically examines the effect of various variables on the second harmonic generation (SHG) coefficients of cylindrical GaAs/Ga1–ηAlηAs quantum dots. The iterative approach and the compact‐density matrix method have been utilized to determine the expression of the SHG coefficient. The outcomes demonstrate that the variation of the SHG coefficient is closely related to structural parameters, external conditions, and incident photon energy.
{"title":"Nonlinear Optical Second Harmonic Generation Characteristics in Cylindrical GaAs/Ga1–ηAlηAs Quantum Dots","authors":"Xiaolong Yan, Xuechao Li, Yawen Cai, Xing Wang","doi":"10.1002/pssb.202400136","DOIUrl":"https://doi.org/10.1002/pssb.202400136","url":null,"abstract":"This article theoretically examines the effect of various variables on the second harmonic generation (SHG) coefficients of cylindrical GaAs/Ga<jats:sub>1–<jats:italic>η</jats:italic></jats:sub>Al<jats:sub><jats:italic>η</jats:italic></jats:sub>As quantum dots. The iterative approach and the compact‐density matrix method have been utilized to determine the expression of the SHG coefficient. The outcomes demonstrate that the variation of the SHG coefficient is closely related to structural parameters, external conditions, and incident photon energy.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"36 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141150520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hao Yang, Jin‐Han Yang, Ming‐Hui Cai, Shuai Tang, Han Ma, Nan Jia, Yan‐Dong Liu, Xiang Zhao, Hai‐Le Yan, Liang Zuo
Effects of Cr alloying on phase stability, magnetism, and electronic structures in both body‐centered cubic (bcc) and face‐centered cubic (fcc) phases and on the transformation from fcc to bcc are studied by first‐principles calculations. Results show that the doped Cr atoms in fcc and bcc phases choose distinct occupation models. This phenomenon can be understood from the amount of electron density of states close to Fermi energy. For magnetism, Cr tends to be antiferromagnetically coupled with the surrounding Fe in the studied phases. The magnetic moment of Fe is greater than that of Cr in bcc, but the order is reversed in fcc. The moment of Fe is dictated by the distance between it and the doped Cr in bcc, whereas it is dominated by spatial orientation with Cr in fcc. For phase stability, it is found that the alloying of Cr prefers destabilizing bcc while tends to stabilize fcc, leading to a strong inhibition of phase transition from fcc to bcc. Notably, the role in the fcc phase is more prominent than that in bcc, which can be associated with the antiferromagnetism between Fe and Cr in fcc.
{"title":"Insight into Cr Alloying on Face‐Centered Cubic to Body‐Centered Cubic Phase Transition in FeCr Alloy","authors":"Hao Yang, Jin‐Han Yang, Ming‐Hui Cai, Shuai Tang, Han Ma, Nan Jia, Yan‐Dong Liu, Xiang Zhao, Hai‐Le Yan, Liang Zuo","doi":"10.1002/pssb.202400158","DOIUrl":"https://doi.org/10.1002/pssb.202400158","url":null,"abstract":"Effects of Cr alloying on phase stability, magnetism, and electronic structures in both body‐centered cubic (bcc) and face‐centered cubic (fcc) phases and on the transformation from fcc to bcc are studied by first‐principles calculations. Results show that the doped Cr atoms in fcc and bcc phases choose distinct occupation models. This phenomenon can be understood from the amount of electron density of states close to Fermi energy. For magnetism, Cr tends to be antiferromagnetically coupled with the surrounding Fe in the studied phases. The magnetic moment of Fe is greater than that of Cr in bcc, but the order is reversed in fcc. The moment of Fe is dictated by the distance between it and the doped Cr in bcc, whereas it is dominated by spatial orientation with Cr in fcc. For phase stability, it is found that the alloying of Cr prefers destabilizing bcc while tends to stabilize fcc, leading to a strong inhibition of phase transition from fcc to bcc. Notably, the role in the fcc phase is more prominent than that in bcc, which can be associated with the antiferromagnetism between Fe and Cr in fcc.","PeriodicalId":20406,"journal":{"name":"Physica Status Solidi B-basic Solid State Physics","volume":"39 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141150501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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