The dielectric constant (ɛr) is an essential parameter as it characterizes the ability to screen charge. Molecular doping is a key strategy to enhance the electronic properties of organic semiconductors, where again ɛr is important because the Coulomb attraction introduced by dopants needs to be overcome to generate carriers. Previous theoretical work has reported collective screening can lead to a dramatic enhancement of ɛr upon doping. Whereas this prediction has been tested in the low‐doping regime, the predicted dielectric catastrophe remains unexplored. Here, metal‐insulator‐semiconductor (MIS) diodes to measure the dielectric constant of organic semiconductors subjected to moderate‐to‐high doping levels is employed. MIS diodes make it possible to measure the dielectric constant at relatively high doping ratios and corresponding high electrical conductivities. This results demonstrated a notable rise in the dielectric constant within a range of ≈3.0–15.0 of n‐ and p‐doped organic semiconductors, resembling the phenomenon of dielectric catastrophe. These observations align with recent theoretical investigations into the impact of molecular doping on ɛr and show the collective behavior of free charges in doped organic semiconductors.
介电常数（ɛr）是一个重要参数，因为它表征了筛选电荷的能力。分子掺杂是增强有机半导体电子特性的关键策略，而ɛr 同样也很重要，因为需要克服掺杂剂引入的库仑吸引力才能产生载流子。先前的理论研究报告指出，集体筛选可导致掺杂后ɛr 的急剧增强。虽然这一预测已在低掺杂体系中得到验证，但所预测的介电灾难仍未得到探索。这里采用了金属-绝缘体-半导体（MIS）二极管来测量中高掺杂水平下有机半导体的介电常数。金属-绝缘体-半导体二极管可以在相对较高的掺杂比和相应的高电导率条件下测量介电常数。结果表明，在 n 掺杂和 p 掺杂的有机半导体中，介电常数在 ≈3.0-15.0 的范围内显著上升，类似于介电灾难现象。这些观察结果与最近有关分子掺杂对ɛr影响的理论研究相吻合，并显示了掺杂有机半导体中自由电荷的集体行为。
{"title":"The Exceptionally High Dielectric Constant of Doped Organic Semiconductors","authors":"Xuwen Yang, Jian Liu, L. Jan Anton Koster","doi":"10.1002/aelm.202400413","DOIUrl":"https://doi.org/10.1002/aelm.202400413","url":null,"abstract":"The dielectric constant (<jats:italic>ɛ<jats:sub>r</jats:sub></jats:italic>) is an essential parameter as it characterizes the ability to screen charge. Molecular doping is a key strategy to enhance the electronic properties of organic semiconductors, where again <jats:italic>ɛ<jats:sub>r</jats:sub></jats:italic> is important because the Coulomb attraction introduced by dopants needs to be overcome to generate carriers. Previous theoretical work has reported collective screening can lead to a dramatic enhancement of <jats:italic>ɛ<jats:sub>r</jats:sub></jats:italic> upon doping. Whereas this prediction has been tested in the low‐doping regime, the predicted dielectric catastrophe remains unexplored. Here, metal‐insulator‐semiconductor (MIS) diodes to measure the dielectric constant of organic semiconductors subjected to moderate‐to‐high doping levels is employed. MIS diodes make it possible to measure the dielectric constant at relatively high doping ratios and corresponding high electrical conductivities. This results demonstrated a notable rise in the dielectric constant within a range of ≈3.0–15.0 of n‐ and p‐doped organic semiconductors, resembling the phenomenon of dielectric catastrophe. These observations align with recent theoretical investigations into the impact of molecular doping on <jats:italic>ɛ<jats:sub>r</jats:sub></jats:italic> and show the collective behavior of free charges in doped organic semiconductors.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142142691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sungjoon Kim, Hyeonseung Ji, Sungjun Kim, Woo Young Choi
Utilizing memristors to increase the density of crossbar arrays requires reducing dependency on transistors. This paper presents an approach where the current limiting function is integrated within the memristor by inducing an AlOx/TaOx layer, thereby limiting overshoot current during filament formation. The reaction between TaOx and Al can be accelerated through annealing, which optimizes the on/off ratio and reduces device‐to‐device variation. Additionally, AlN is inserted to inhibit the movement of oxygen ions to the bottom electrode, improving conductive filament reoxidation. Furthermore, biological synaptic properties are examined using electrical pulse schemes, revealing multibit characteristics of >5‐bit. After the structure optimization, 24 × 24 crossbar arrays are fabricated, allowing 100% of cells to achieve self‐compliance filament formation without hard breakdown. Moreover, the crossbar array demonstrates an on/off ratio of over 4 × 102. Additionally, a multibit‐encoded neuromorphic system is proposed based on the device's multibit capability. The number of synapses can be significantly reduced by grouping input data into a single memristor device. When comparing classification accuracies, 97.14% and 95.54% are observed without and with encoding. The improvements in device structure and encoding method presented in this study enable highly integrated crossbar arrays and efficient neuromorphic systems.
{"title":"Enhanced Reliability and Self‐Compliance of Synaptic Arrays for Multibit Encoded Neuromorphic Systems","authors":"Sungjoon Kim, Hyeonseung Ji, Sungjun Kim, Woo Young Choi","doi":"10.1002/aelm.202400282","DOIUrl":"https://doi.org/10.1002/aelm.202400282","url":null,"abstract":"Utilizing memristors to increase the density of crossbar arrays requires reducing dependency on transistors. This paper presents an approach where the current limiting function is integrated within the memristor by inducing an AlO<jats:sub>x</jats:sub>/TaO<jats:sub>x</jats:sub> layer, thereby limiting overshoot current during filament formation. The reaction between TaO<jats:sub>x</jats:sub> and Al can be accelerated through annealing, which optimizes the on/off ratio and reduces device‐to‐device variation. Additionally, AlN is inserted to inhibit the movement of oxygen ions to the bottom electrode, improving conductive filament reoxidation. Furthermore, biological synaptic properties are examined using electrical pulse schemes, revealing multibit characteristics of >5‐bit. After the structure optimization, 24 × 24 crossbar arrays are fabricated, allowing 100% of cells to achieve self‐compliance filament formation without hard breakdown. Moreover, the crossbar array demonstrates an on/off ratio of over 4 × 10<jats:sup>2</jats:sup>. Additionally, a multibit‐encoded neuromorphic system is proposed based on the device's multibit capability. The number of synapses can be significantly reduced by grouping input data into a single memristor device. When comparing classification accuracies, 97.14% and 95.54% are observed without and with encoding. The improvements in device structure and encoding method presented in this study enable highly integrated crossbar arrays and efficient neuromorphic systems.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142142692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Atomically thin transition metal dichalcogenides (TMDs) heterostructures provide a rich platform for exploring fascinating physics and engineering strategies. A pressure strategy is developed to effectively manipulate the physical properties in such heterostructures. However, there is still a lack of studies on the corresponding pressure-modulated evolution of carrier dynamics, which is crucial to the performance of electronic and optoelectronic devices. Here, utilizing the diamond anvil cell, the interlayer exciton dynamics of WS2/MoSe2 heterostructure are subtly manipulated by pressure. Intriguingly, with pressure modulation, the enhanced interlayer coupling accelerates the recombination of spatially separated electron and hole, which significantly shortens the interlayer exciton lifetime from 37.10 ps at 0.0 Gpa to 3.03 ps at 2.2 Gpa. For comparison, the intralayer exciton lifetime of monolayer MoSe2 is increased due to the transition of direct to indirect bandgap under pressure. Furthermore, the pressure-regulated band structure and interlayer coupling are confirmed by photoluminescence and Raman spectroscopy. The results demonstrate that pressure provides a powerful tuning knob for interlayer exciton relaxation of TMDs heterostructure, which is attractive to various electronic and optoelectronic applications based on such heterostructure.
{"title":"Ultrafast Decay of Interlayer Exciton in WS2/MoSe2 Heterostructure Under Pressure","authors":"Zhiying Bai, He Zhang, Jiaqi He, Dawei He, Jiarong Wang, Wenwen Wu, Yinglin Zhang, Wenjie Wang, Yongsheng Wang, Xiaohui Yu, Xiaoxian Zhang","doi":"10.1002/aelm.202400333","DOIUrl":"https://doi.org/10.1002/aelm.202400333","url":null,"abstract":"Atomically thin transition metal dichalcogenides (TMDs) heterostructures provide a rich platform for exploring fascinating physics and engineering strategies. A pressure strategy is developed to effectively manipulate the physical properties in such heterostructures. However, there is still a lack of studies on the corresponding pressure-modulated evolution of carrier dynamics, which is crucial to the performance of electronic and optoelectronic devices. Here, utilizing the diamond anvil cell, the interlayer exciton dynamics of WS<sub>2</sub>/MoSe<sub>2</sub> heterostructure are subtly manipulated by pressure. Intriguingly, with pressure modulation, the enhanced interlayer coupling accelerates the recombination of spatially separated electron and hole, which significantly shortens the interlayer exciton lifetime from 37.10 ps at 0.0 Gpa to 3.03 ps at 2.2 Gpa. For comparison, the intralayer exciton lifetime of monolayer MoSe<sub>2</sub> is increased due to the transition of direct to indirect bandgap under pressure. Furthermore, the pressure-regulated band structure and interlayer coupling are confirmed by photoluminescence and Raman spectroscopy. The results demonstrate that pressure provides a powerful tuning knob for interlayer exciton relaxation of TMDs heterostructure, which is attractive to various electronic and optoelectronic applications based on such heterostructure.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jae Hoon Lee, Yonghee Lee, Joon-Kyu Han, Kyung Do Kim, Seung Ryong Byun, Hyeon Woo Park, Cheol Seong Hwang
This work investigates the mechanism for the memory window (MW) suppression of the ferroelectric-thin film transistors (FETFTs) with an amorphous indium-gallium-zinc (a-IGZO) channel. a-IGZO generally has an n-type character with a high bandgap (>3 eV) and a high density of gap states, hindering the carrier type inversion. Therefore, the negative ferroelectric (FE) bound charges at the FE layer/a-IGZO interface must be compensated by the positive charges of the oxygen vacancy in the a-IGZO layer. In contrast, accumulated electrons can compensate for the positive FE-bound charges. Such a bound charge compensation mechanism complicates the FETFT operation and precise understanding. Experiments and simulations confirm that feasible FE switching in the bottom-TiN or P++-Si/Al-doped HfO2/a-IGZO/top-TiN structure can occur only when the countercharges in the a-IGZO layer compensate the positive and negative bound charges. More importantly, the Al-doped HfO2/a-IGZO interface generally involves electron trapping, which hinders FE switching and achieving a MW for the TiN gate case. When replacing the TiN gate with the P++-Si gate, the suppressed FE polarization by the depolarization effect from the SiO2 interface layer can mitigate electron accumulation. Consequently, the P++-Si bottom electrode (BE) is more advantageous than the TiN BE regarding a MW of FETFT.
这项研究探讨了具有非晶铟镓锌 (a-IGZO) 沟道的铁电薄膜晶体管 (FETFT) 的记忆窗口 (MW) 抑制机制。a-IGZO 通常具有 n 型特性，具有高带隙（>3 eV）和高间隙态密度，阻碍了载流子类型的反转。因此，FE 层/a-IGZO 界面的负铁电（FE）束缚电荷必须由 a-IGZO 层中氧空位的正电荷来补偿。相反，累积的电子可以补偿正的 FE 结合电荷。这种束缚电荷补偿机制使 FETFT 的操作和精确理解变得复杂。实验和模拟证实，只有当 a-IGZO 层中的反电荷能补偿正负束缚电荷时，底部-TiN 或 P++-Si/Al 掺杂 HfO2/a-IGZO/top-TiN 结构中才会出现可行的 FE 开关。更重要的是，铝掺杂的 HfO2/a-IGZO 界面通常会产生电子捕获，这阻碍了 FE 开关和实现 TiN 栅极的 MW。当用 P++-Si 栅极取代 TiN 栅极时，二氧化硅界面层的去极化效应抑制了 FE 极化，从而减轻了电子积聚。因此，就 FETFT 的最大功率而言，P++-Si 底电极 (BE) 比 TiN 底电极更具优势。
{"title":"Gate Engineering Effect in Ferroelectric Field-Effect Transistors with Al-Doped HfO2 Thin Film and Amorphous Indium-Gallium-Zinc-Oxide Channel","authors":"Jae Hoon Lee, Yonghee Lee, Joon-Kyu Han, Kyung Do Kim, Seung Ryong Byun, Hyeon Woo Park, Cheol Seong Hwang","doi":"10.1002/aelm.202400516","DOIUrl":"https://doi.org/10.1002/aelm.202400516","url":null,"abstract":"This work investigates the mechanism for the memory window (MW) suppression of the ferroelectric-thin film transistors (FETFTs) with an amorphous indium-gallium-zinc (<i>a</i>-IGZO) channel. <i>a</i>-IGZO generally has an n-type character with a high bandgap (>3 eV) and a high density of gap states, hindering the carrier type inversion. Therefore, the negative ferroelectric (FE) bound charges at the FE layer/<i>a</i>-IGZO interface must be compensated by the positive charges of the oxygen vacancy in the <i>a</i>-IGZO layer. In contrast, accumulated electrons can compensate for the positive FE-bound charges. Such a bound charge compensation mechanism complicates the FETFT operation and precise understanding. Experiments and simulations confirm that feasible FE switching in the bottom-TiN or <i>P</i><sup>++</sup>-Si/Al-doped HfO<sub>2</sub>/<i>a</i>-IGZO/top-TiN structure can occur only when the countercharges in the <i>a</i>-IGZO layer compensate the positive and negative bound charges. More importantly, the Al-doped HfO<sub>2</sub>/<i>a</i>-IGZO interface generally involves electron trapping, which hinders FE switching and achieving a MW for the TiN gate case. When replacing the TiN gate with the <i>P</i><sup>++</sup>-Si gate, the suppressed FE polarization by the depolarization effect from the SiO<sub>2</sub> interface layer can mitigate electron accumulation. Consequently, the <i>P</i><sup>++</sup>-Si bottom electrode (BE) is more advantageous than the TiN BE regarding a MW of FETFT.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142131056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yan Sun, Corentin Morice, Damien Garrot, Raphael Weil, Kenji Watanabe, Takashi Taniguchi, Miguel Monteverde, Alexei D. Chepelianskii
Understanding the quantum transport properties of (Two-dimensional) 2D perovskite heterostructures is key to interpreting their electronic performance and promoting optoelectronic devices. Here, it is shown that clear Shubnikov-de Hass oscillation appears in the heterostructure of monocrystalline 2D perovskites and graphene, thanks to the clean interface. An efficient charge transfer between perovskite nanosheets and graphene is found, facilitating the separation of electrons and holes at the interface. The relation between the charge transfer efficiency and microscopic interface structures is quantitatively described. The evidence of photo-assisted transport from the photo-response of magnetoresistance is revealed, which happens between Landau levels of two graphene layers mediated by hot carriers in the perovskite layer, overcoming the barrier from the organic layers in the Ruddlesden-Popper perovskite phase. These results provide a picture to understand the transport behavior of 2D perovskite/graphene heterostructure and a reference for the controlled design of interfaces in perovskite optoelectronic devices.
{"title":"Quantum Transport and Spectroscopy of 2D Perovskite/Graphene Heterostructures","authors":"Yan Sun, Corentin Morice, Damien Garrot, Raphael Weil, Kenji Watanabe, Takashi Taniguchi, Miguel Monteverde, Alexei D. Chepelianskii","doi":"10.1002/aelm.202400211","DOIUrl":"https://doi.org/10.1002/aelm.202400211","url":null,"abstract":"Understanding the quantum transport properties of (Two-dimensional) 2D perovskite heterostructures is key to interpreting their electronic performance and promoting optoelectronic devices. Here, it is shown that clear Shubnikov-de Hass oscillation appears in the heterostructure of monocrystalline 2D perovskites and graphene, thanks to the clean interface. An efficient charge transfer between perovskite nanosheets and graphene is found, facilitating the separation of electrons and holes at the interface. The relation between the charge transfer efficiency and microscopic interface structures is quantitatively described. The evidence of photo-assisted transport from the photo-response of magnetoresistance is revealed, which happens between Landau levels of two graphene layers mediated by hot carriers in the perovskite layer, overcoming the barrier from the organic layers in the Ruddlesden-Popper perovskite phase. These results provide a picture to understand the transport behavior of 2D perovskite/graphene heterostructure and a reference for the controlled design of interfaces in perovskite optoelectronic devices.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142123962","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wonho Song, Jung‐Yong Lee, Junhyung Kim, Jinyoung Park, Jaehyeong Jo, Eunseok Hyun, Jiwan Kim, Hyunjae Park, Daejin Eom, Gahyun Choi, Kibog Park
The effective work‐function of metal electrode is one of the major factors to determine the threshold voltage of metal/oxide/semiconductor junction. In this work, it is demonstrated experimentally that the effective work‐function of the Aluminum (Al) electrode in Al/SiO2/n‐Si junction increases significantly by ≈1.04 eV with the graphene interlayer inserted at Al/SiO2 interface. The device‐physical analysis of solving Poisson equation analytically is provided when the flat‐band voltage is applied to the junction, supporting that the large tuning of Al effective work‐function may originate from the electric dipole layer formed by the off‐centric distribution of electron orbitals between Al and graphene layer. Our work suggests the feasibility of constructing the dual‐metal gate CMOS circuitry just by using Al electrodes with area‐specific underlying graphene interlayer.
{"title":"Largely‐Tuned Effective Work‐Function of Al/Graphene/SiO2/Si Junction with Electric Dipole Layer at Al/Graphene Interface","authors":"Wonho Song, Jung‐Yong Lee, Junhyung Kim, Jinyoung Park, Jaehyeong Jo, Eunseok Hyun, Jiwan Kim, Hyunjae Park, Daejin Eom, Gahyun Choi, Kibog Park","doi":"10.1002/aelm.202400139","DOIUrl":"https://doi.org/10.1002/aelm.202400139","url":null,"abstract":"The effective work‐function of metal electrode is one of the major factors to determine the threshold voltage of metal/oxide/semiconductor junction. In this work, it is demonstrated experimentally that the effective work‐function of the Aluminum (Al) electrode in Al/SiO<jats:sub>2</jats:sub>/n‐Si junction increases significantly by ≈1.04 eV with the graphene interlayer inserted at Al/SiO<jats:sub>2</jats:sub> interface. The device‐physical analysis of solving Poisson equation analytically is provided when the flat‐band voltage is applied to the junction, supporting that the large tuning of Al effective work‐function may originate from the electric dipole layer formed by the off‐centric distribution of electron orbitals between Al and graphene layer. Our work suggests the feasibility of constructing the dual‐metal gate CMOS circuitry just by using Al electrodes with area‐specific underlying graphene interlayer.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhengpeng Wang, Fei Tang, Fang-Fang Ren, Hongwei Liang, Xiangyuan Cui, Shijie Xu, Shulin Gu, Rong Zhang, Youdou Zheng, Jiandong Ye
In this work, the optical transition of self-trapped excitons (STEs) and the emergent green emission in β-Ga2O3 samples with/without Sn impurities at various doping levels have been investigated via temperature- and power-dependent photoluminescence. The ultraviolet (UV) emissions ≈ 3.40 eV unanimously exhibit an excitonic nature related to STEs and typical negative thermal quenching (NTQ) characters. The NTQ activation energy decreases from 103.56 to 42.37 meV with the increased electron concentration from 2.1 × 1016 to 6.7 × 1018 cm−3, indicative of the reduced energy barrier that electrons should overcome to form stable STEs due to the lift-up of Fermi level. In comparison, the green emissions ≈ 2.35 eV with two quenching channels are observed only in samples with Sn impurities at cryogenic temperatures. One channel is the nsnp-ns2 transition of Sn2+, the other is donor-acceptor pair recombination via (2VGa-Sni)2− complex, which is energetically favorable as evidenced by density functional theory calculations. The semi-classical quantum theory models fitting proves the transition from green to UV emissions with elevated temperature. The enhanced STEs emission with distinguished NTQ effect strengthens evidence that the stable polarons inherently limit the transport of holes in Ga2O3, and also support the potential of Ga2O3 materials for the development of UV optoelectronics.
{"title":"Unraveling Abnormal Thermal Quenching of Sub-Gap Emission in β-Ga2O3","authors":"Zhengpeng Wang, Fei Tang, Fang-Fang Ren, Hongwei Liang, Xiangyuan Cui, Shijie Xu, Shulin Gu, Rong Zhang, Youdou Zheng, Jiandong Ye","doi":"10.1002/aelm.202400315","DOIUrl":"https://doi.org/10.1002/aelm.202400315","url":null,"abstract":"In this work, the optical transition of self-trapped excitons (STEs) and the emergent green emission in β-Ga<sub>2</sub>O<sub>3</sub> samples with/without Sn impurities at various doping levels have been investigated via temperature- and power-dependent photoluminescence. The ultraviolet (UV) emissions ≈ 3.40 eV unanimously exhibit an excitonic nature related to STEs and typical negative thermal quenching (NTQ) characters. The NTQ activation energy decreases from 103.56 to 42.37 meV with the increased electron concentration from 2.1 × 10<sup>16</sup> to 6.7 × 10<sup>18</sup> cm<sup>−3</sup>, indicative of the reduced energy barrier that electrons should overcome to form stable STEs due to the lift-up of Fermi level. In comparison, the green emissions ≈ 2.35 eV with two quenching channels are observed only in samples with Sn impurities at cryogenic temperatures. One channel is the <i>nsnp</i>-<i>ns</i><sup>2</sup> transition of Sn<sup>2+</sup>, the other is donor-acceptor pair recombination via (2V<sub>Ga</sub>-Sn<sub>i</sub>)<sup>2−</sup> complex, which is energetically favorable as evidenced by density functional theory calculations. The semi-classical quantum theory models fitting proves the transition from green to UV emissions with elevated temperature. The enhanced STEs emission with distinguished NTQ effect strengthens evidence that the stable polarons inherently limit the transport of holes in Ga<sub>2</sub>O<sub>3</sub>, and also support the potential of Ga<sub>2</sub>O<sub>3</sub> materials for the development of UV optoelectronics.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142118177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexandros Sarantopoulos, Kristof Lange, Francisco Rivadulla, Stephan Menzel, Regina Dittmann
Enhancing the switching speed of oxide‐based memristive devices at a low voltage level is crucial for their use as non‐volatile memory and their integration into emerging computing paradigms such as neuromorphic computing. Efforts to accelerate the switching speed often result in an energy trade‐off, leading to an increase in the minimum working voltage. In this study, an innovative solution is presented: the introduction of a low thermal conductivity layer placed within the active electrode, which impedes the dissipation of heat generated during the switching process. The result is a notable acceleration in the switching speed of the memristive model system SrTiO3 by a remarkable factor of 103, while preserving the integrity of the switching layer and the interfaces with the electrodes, rendering it adaptable to various filamentary memristive systems. The incorporation of HfO2 or TaOx as heat‐blocking layers not only streamlines the fabrication process but also ensures compatibility with complementary metal‐oxide‐semiconductor technology.
{"title":"Resistive Switching Acceleration Induced by Thermal Confinement","authors":"Alexandros Sarantopoulos, Kristof Lange, Francisco Rivadulla, Stephan Menzel, Regina Dittmann","doi":"10.1002/aelm.202400555","DOIUrl":"https://doi.org/10.1002/aelm.202400555","url":null,"abstract":"Enhancing the switching speed of oxide‐based memristive devices at a low voltage level is crucial for their use as non‐volatile memory and their integration into emerging computing paradigms such as neuromorphic computing. Efforts to accelerate the switching speed often result in an energy trade‐off, leading to an increase in the minimum working voltage. In this study, an innovative solution is presented: the introduction of a low thermal conductivity layer placed within the active electrode, which impedes the dissipation of heat generated during the switching process. The result is a notable acceleration in the switching speed of the memristive model system SrTiO<jats:sub>3</jats:sub> by a remarkable factor of 10<jats:sup>3</jats:sup>, while preserving the integrity of the switching layer and the interfaces with the electrodes, rendering it adaptable to various filamentary memristive systems. The incorporation of HfO<jats:sub>2</jats:sub> or TaO<jats:sub><jats:italic>x</jats:italic></jats:sub> as heat‐blocking layers not only streamlines the fabrication process but also ensures compatibility with complementary metal‐oxide‐semiconductor technology.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vy Anh Tran, Van Thuan Le, Thi Thu Trinh Phan, Minh Tuan Trinh
Solar energy has become increasingly important in today's world as a clean and abundant energy source. Its significance spans across environmental, economic, and technological dimensions, making it a cornerstone for the future of energy production. However, widespread adoption of solar energy is hindered by the high costs associated with large‐scale implementation. To facilitate a broad transition to renewable energy, it is essential to actively explore various emerging materials for highly efficient and cost‐effective solar cells. With the recent advances in materials science, numerous emerging materials show high potential for these purposes. For example, rapid progress in perovskite research highlights its potential for making low‐cost and highly efficient solar cells. This review presents a comprehensive overview of emerging active materials for solar cells, covering fundamental concepts, progress, and recent advancements. The key breakthroughs, challenges, and prospects will be highlighted with a focus on solar cells based on organic materials, perovskite materials, and colloidal quantum dots. By delving into the progress and obstacles associated with these materials, this review offers valuable insights into the development of solar cell technology. As it is continued to unlock the potential of solar energy, this abundant and environmentally friendly energy source becomes increasingly viable.
{"title":"Emerging Active Materials for Solar Cells: Progress and Prospects","authors":"Vy Anh Tran, Van Thuan Le, Thi Thu Trinh Phan, Minh Tuan Trinh","doi":"10.1002/aelm.202400530","DOIUrl":"https://doi.org/10.1002/aelm.202400530","url":null,"abstract":"Solar energy has become increasingly important in today's world as a clean and abundant energy source. Its significance spans across environmental, economic, and technological dimensions, making it a cornerstone for the future of energy production. However, widespread adoption of solar energy is hindered by the high costs associated with large‐scale implementation. To facilitate a broad transition to renewable energy, it is essential to actively explore various emerging materials for highly efficient and cost‐effective solar cells. With the recent advances in materials science, numerous emerging materials show high potential for these purposes. For example, rapid progress in perovskite research highlights its potential for making low‐cost and highly efficient solar cells. This review presents a comprehensive overview of emerging active materials for solar cells, covering fundamental concepts, progress, and recent advancements. The key breakthroughs, challenges, and prospects will be highlighted with a focus on solar cells based on organic materials, perovskite materials, and colloidal quantum dots. By delving into the progress and obstacles associated with these materials, this review offers valuable insights into the development of solar cell technology. As it is continued to unlock the potential of solar energy, this abundant and environmentally friendly energy source becomes increasingly viable.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Transition metal dichalcogenides (TMDCs) based large‐scale p‐type floating‐gate field‐effect transistor (FGFET) memory array has been fabricated for the first time. Chemical‐vapor‐deposition grown seamless co‐planes 2H‐ and 1T′‐MoTe2 serve as the channel and source/drain electrodes, respectively. High‐κ Al2O3 layers act as the tunneling and blocking layers. Arrayed Pd/Au serves as floating and top gates. The overall performances of the devices are excellent among those of the reported TMDCs‐based FGFET memories. Typical device exhibits large memory windows of ≈11.5 and 2.8 V and on/off ratios of ≈104 and 103 in gate voltage sweep ranges of ±10 and ±5 V, respectively, with long retention time of more than 105 s and good stress endurance of more than 5 × 104 programming/erasing cycles. The conductance of the device can be precisely tuned by applying short potentiative and depressive ±5 V voltage pulses. The device yields are 100% and 93% under ±10 and ±5 V, respectively. The whole fabrication process is free from the transfer process and compatible with traditional silicon technology. This work paves the way for the application of TMDCs in large‐scale integrated circuits.
首次制造出了基于过渡金属二卤化物（TMDCs）的大规模 p 型浮栅场效应晶体管（FGFET）存储器阵列。化学气相沉积生长的无缝共面 2H- 和 1T′-MoTe2 分别作为沟道和源/漏电极。高κ Al2O3 层作为隧道层和阻挡层。阵列钯/金作为浮栅和顶栅。在已报道的基于 TMDCs 的 FGFET 存储器中，该器件的整体性能非常出色。在栅极电压扫描范围为 ±10 V 和 ±5 V 时，典型器件的存储窗口分别为 ≈11.5 V 和 2.8 V，导通/关断比分别为 ≈104 和 103，保持时间超过 105 s，应力耐久性超过 5 × 104 个编程/消除周期。该器件的电导可通过施加±5 V 的短电位和抑制电压脉冲进行精确调节。在 ±10 V 和 ±5 V 电压下，器件良率分别为 100% 和 93%。整个制造过程无需转移工艺，与传统硅技术兼容。这项工作为 TMDC 在大规模集成电路中的应用铺平了道路。
{"title":"Large‐Scale p‐Type Nonvolatile FGFET Memory Array Based on 2H‐MoTe2","authors":"Minglai Li, Zhixuan Cheng, Xionghui Jia, Jiamin Chen, Wanjin Xu, Yanping Li, Lun Dai","doi":"10.1002/aelm.202400386","DOIUrl":"https://doi.org/10.1002/aelm.202400386","url":null,"abstract":"Transition metal dichalcogenides (TMDCs) based large‐scale <jats:italic>p</jats:italic>‐type floating‐gate field‐effect transistor (FGFET) memory array has been fabricated for the first time. Chemical‐vapor‐deposition grown seamless co‐planes 2H‐ and 1T′‐MoTe<jats:sub>2</jats:sub> serve as the channel and source/drain electrodes, respectively. High‐κ Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> layers act as the tunneling and blocking layers. Arrayed Pd/Au serves as floating and top gates. The overall performances of the devices are excellent among those of the reported TMDCs‐based FGFET memories. Typical device exhibits large memory windows of ≈11.5 and 2.8 V and on/off ratios of ≈10<jats:sup>4</jats:sup> and 10<jats:sup>3</jats:sup> in gate voltage sweep ranges of ±10 and ±5 V, respectively, with long retention time of more than 10<jats:sup>5</jats:sup> s and good stress endurance of more than 5 × 10<jats:sup>4</jats:sup> programming/erasing cycles. The conductance of the device can be precisely tuned by applying short potentiative and depressive ±5 V voltage pulses. The device yields are 100% and 93% under ±10 and ±5 V, respectively. The whole fabrication process is free from the transfer process and compatible with traditional silicon technology. This work paves the way for the application of TMDCs in large‐scale integrated circuits.","PeriodicalId":110,"journal":{"name":"Advanced Electronic Materials","volume":null,"pages":null},"PeriodicalIF":6.2,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142101307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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