S. Chatterjee, S. Sahu, Binit Mallick, Umang Singh, S. Bhunia, R. Sarkar, Dipankar Saha, A. Laha
Three sets of InGaN/GaN nanowire (NW) heterostructures are grown on Si(111) substrates under different growth conditions. A quasi‐two‐dimensional p‐GaN layer is grown on top of those structures using the epitaxial lateral overgrowth (ELOG) technique. Finally, the light‐emitting diodes (LED) are fabricated using these hybrid nanostructures following standard fabrication techniques. Electroluminescence (EL) measurement confirmed the emission wavelengths of 530.0 nm (green), 608.3 nm (orange), and 632.5 nm (red). The knee voltages of the devices are estimated to be in the range of 2.18–2.89 V, with higher knee voltages for samples emitting lower wavelengths. Further analysis of forward bias electrical characteristics suggests the dominance of tunneling current and an increase in the defect density in the heterostructures emitting higher wavelengths.
{"title":"InGaN/GaN Hybrid‐Nanostructure Light Emitting Diodes with Emission Wavelength Green and Beyond","authors":"S. Chatterjee, S. Sahu, Binit Mallick, Umang Singh, S. Bhunia, R. Sarkar, Dipankar Saha, A. Laha","doi":"10.1002/pssr.202400147","DOIUrl":"https://doi.org/10.1002/pssr.202400147","url":null,"abstract":"Three sets of InGaN/GaN nanowire (NW) heterostructures are grown on Si(111) substrates under different growth conditions. A quasi‐two‐dimensional p‐GaN layer is grown on top of those structures using the epitaxial lateral overgrowth (ELOG) technique. Finally, the light‐emitting diodes (LED) are fabricated using these hybrid nanostructures following standard fabrication techniques. Electroluminescence (EL) measurement confirmed the emission wavelengths of 530.0 nm (green), 608.3 nm (orange), and 632.5 nm (red). The knee voltages of the devices are estimated to be in the range of 2.18–2.89 V, with higher knee voltages for samples emitting lower wavelengths. Further analysis of forward bias electrical characteristics suggests the dominance of tunneling current and an increase in the defect density in the heterostructures emitting higher wavelengths.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141643682","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}
Xijian Zhang, Jidong Jin, Jaekyun Kim, Claudio Balocco, Jiawei Zhang, Aimin Song
This study presents TiO2‐based Schottky diodes designed as bidirectional switches for bipolar resistive memories. The TiO2 films in these Schottky diodes are prepared through an anodization process. The reverse current of these diodes exhibits an exponential increase with rising reverse voltage, ultimately matching the forward current. When two diodes are connected back‐to‐back, they demonstrate superior current‐voltage symmetry and provide a wider off‐state voltage range compared to a single diode, reaching up to 3.65 V. The adjustable off‐state voltage range (0.40 V to 3.65 V) of the switch, whether utilizing two diodes or a single diode, correlates well with the TiO2 layer thickness and oxygen partial pressure during Pt electrode sputtering. These diodes possess bidirectional switching characteristics and can serve as effective switch elements to address the sneak‐path issue in bipolar resistive memories.This article is protected by copyright. All rights reserved.
本研究介绍了将基于二氧化钛的肖特基二极管设计成双极电阻式存储器的双向开关。这些肖特基二极管中的二氧化钛薄膜是通过阳极氧化工艺制备的。这些二极管的反向电流随着反向电压的升高呈指数增长，最终与正向电流相匹配。当两个二极管背靠背连接时，它们显示出卓越的电流-电压对称性，并提供比单个二极管更宽的离态电压范围，最高可达 3.65 V。无论是使用两个二极管还是单个二极管，开关的可调离态电压范围（0.40 V 至 3.65 V）都与铂电极溅射过程中的二氧化钛层厚度和氧分压密切相关。这些二极管具有双向开关特性，可以作为有效的开关元件，解决双极电阻式存储器中的潜行路径问题。本文受版权保护。
{"title":"TiO2‐Based Schottky Diodes as Bidirectional Switches for Bipolar Resistive Memories","authors":"Xijian Zhang, Jidong Jin, Jaekyun Kim, Claudio Balocco, Jiawei Zhang, Aimin Song","doi":"10.1002/pssr.202400156","DOIUrl":"https://doi.org/10.1002/pssr.202400156","url":null,"abstract":"This study presents TiO2‐based Schottky diodes designed as bidirectional switches for bipolar resistive memories. The TiO2 films in these Schottky diodes are prepared through an anodization process. The reverse current of these diodes exhibits an exponential increase with rising reverse voltage, ultimately matching the forward current. When two diodes are connected back‐to‐back, they demonstrate superior current‐voltage symmetry and provide a wider off‐state voltage range compared to a single diode, reaching up to 3.65 V. The adjustable off‐state voltage range (0.40 V to 3.65 V) of the switch, whether utilizing two diodes or a single diode, correlates well with the TiO2 layer thickness and oxygen partial pressure during Pt electrode sputtering. These diodes possess bidirectional switching characteristics and can serve as effective switch elements to address the sneak‐path issue in bipolar resistive memories.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141336472","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}
To better verify the potential of Rb2Pb2O3 as p‐type transparent conductive oxides (TCOs), the structural, electronic, mechanical, transport and optical properties of Rb2Pb2O3 were calculated in detail under the framework of density functional theory (DFT). Significantly, Rb2Pb2O3 is a p‐type semiconductor with an indirect 2.82 eV bandgap. Here, the Pb‐6p and O‐2p orbits hybridized to form ionic Pb‐O bonds, which determines the degree of localization of electrons in valence band maximum. Interestingly, Rb‐O bond is extremely weak, and the Rb atom is rarely involved in bonding interactions. This contributes to isotropy, ductility and good mobility of Rb2Pb2O3, making it soft and suitable for application in flexible electronics. More importantly, as a transparent conductive material, Rb2Pb2O3 not only shows good transparency in the visible region, but also has good electrical conductivity. Therefore, we preliminarily identified Rb2Pb2O3 as an intrinsic p‐TCO with good performances. Our theoretical finding provides a new candidate for p‐TCOs and paves a way for further performance improvement of Rb2Pb2O3.This article is protected by copyright. All rights reserved.
{"title":"Electronic, transport and optical properties of potential transparent conductive material Rb2Pb2O3","authors":"Jing-Yi Xia, Wei Zeng, Zheng-Tang Liu, Qi-Jun Liu, Juan Gao, Zhen Jiao","doi":"10.1002/pssr.202400135","DOIUrl":"https://doi.org/10.1002/pssr.202400135","url":null,"abstract":"To better verify the potential of Rb2Pb2O3 as p‐type transparent conductive oxides (TCOs), the structural, electronic, mechanical, transport and optical properties of Rb2Pb2O3 were calculated in detail under the framework of density functional theory (DFT). Significantly, Rb2Pb2O3 is a p‐type semiconductor with an indirect 2.82 eV bandgap. Here, the Pb‐6p and O‐2p orbits hybridized to form ionic Pb‐O bonds, which determines the degree of localization of electrons in valence band maximum. Interestingly, Rb‐O bond is extremely weak, and the Rb atom is rarely involved in bonding interactions. This contributes to isotropy, ductility and good mobility of Rb2Pb2O3, making it soft and suitable for application in flexible electronics. More importantly, as a transparent conductive material, Rb2Pb2O3 not only shows good transparency in the visible region, but also has good electrical conductivity. Therefore, we preliminarily identified Rb2Pb2O3 as an intrinsic p‐TCO with good performances. Our theoretical finding provides a new candidate for p‐TCOs and paves a way for further performance improvement of Rb2Pb2O3.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141337005","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}
Liang Wang, Yongxiang Zhang, Mengtong Yan, Junxi Zhang, Hongbo Lu, Mei Lyu, Jun Zhu
Dion‐Jacobson (DJ) phase perovskites have received attention in the field of amplified spontaneous radiation (ASE) and lasers due to their excellent structural stability and charge transfer performance. However, the effect of the diamine cation size on the ASE properties of DJ phase perovskite has not been studied. Herein, we systematically study the effect and the results show that tuning the size of the diamine cation can inhibit the formation of the small‐n phases, reduce the surface roughness, and passivate defects of DJ phase perovskite films. Based on those, we realize the low‐threshold ASE (65 μJ cm−2 under nanosecond laser excitation) of the 1,3‐propylenediamine cation (PDA)‐based DJ phase perovskite films. Additionally, the film exhibits excellent photostability. The ASE intensity remains at 90% of the original value after a pulsed laser irradiation of 3000 μJ cm−2 for 120 min. This work provides a strategy to realize high‐performance DJ phase perovskite ASE and lasers.This article is protected by copyright. All rights reserved.
Dion-Jacobson (DJ) 相包晶石因其出色的结构稳定性和电荷转移性能，在放大自发辐射（ASE）和激光领域备受关注。然而，关于二胺阳离子尺寸对 DJ 相包晶石 ASE 性能的影响还没有研究。在此，我们对其影响进行了系统研究，结果表明，调整二胺阳离子的大小可以抑制小n相的形成，降低表面粗糙度，钝化DJ相包晶石薄膜的缺陷。在此基础上，我们实现了 1,3-丙二胺阳离子（PDA）基 DJ 相包晶石薄膜的低阈值 ASE（纳秒激光激发下 65 μJ cm-2）。此外，该薄膜还具有出色的光稳定性。在 3000 μJ cm-2 的脉冲激光照射 120 分钟后，ASE 强度仍保持在原始值的 90%。本文受版权保护。本文受版权保护。
{"title":"Low‐threshold Amplified Spontaneous Emission of Dion‐Jacobson Phase Perovskite Films Achieved by Tuning Diamine Cation Size","authors":"Liang Wang, Yongxiang Zhang, Mengtong Yan, Junxi Zhang, Hongbo Lu, Mei Lyu, Jun Zhu","doi":"10.1002/pssr.202400080","DOIUrl":"https://doi.org/10.1002/pssr.202400080","url":null,"abstract":"Dion‐Jacobson (DJ) phase perovskites have received attention in the field of amplified spontaneous radiation (ASE) and lasers due to their excellent structural stability and charge transfer performance. However, the effect of the diamine cation size on the ASE properties of DJ phase perovskite has not been studied. Herein, we systematically study the effect and the results show that tuning the size of the diamine cation can inhibit the formation of the small‐n phases, reduce the surface roughness, and passivate defects of DJ phase perovskite films. Based on those, we realize the low‐threshold ASE (65 μJ cm−2 under nanosecond laser excitation) of the 1,3‐propylenediamine cation (PDA)‐based DJ phase perovskite films. Additionally, the film exhibits excellent photostability. The ASE intensity remains at 90% of the original value after a pulsed laser irradiation of 3000 μJ cm−2 for 120 min. This work provides a strategy to realize high‐performance DJ phase perovskite ASE and lasers.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141364363","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}
Masayuki Imanishi, S. Usami, K. Murakami, K. Okumura, Kosuke Nakamura, K. Kakinouchi, Y. Otoki, Tomio Yamashita, Naohiro Tsurumi, Satoshi Tamura, Hiroshi Ohno, Y. Okayama, Taku Fujimori, Seiji Nagai, Miki Moriyama, Yusuke Mori
The Na‐flux method is expected to be a key GaN growth technique for obtainning ideal bulk GaN crystals. Herein we describe the structural quality of the latest GaN crystals grown using the Na‐flux method and, for the first time, the characteristics of a vertical transistor fabricated on a GaN substrate grown using this method. Vertical transistors exhibit normally off operation with a gate voltage threshold exceeding 2 V and a maximum drain current of 3.3 A during the on‐state operation. Additionally, it demonstrates a breakdown voltage exceeding 600 V and a low leakage current during off‐state operation. We also describe that the variation in the on‐resistance can be minimized using GaN substrates with minimal off‐angle variations. This is crucial for achieving the large‐current chips required for future demonstration of actual devices. In addition, the reverse I–V characteristics of the parasitic p–n junction diode structures indicate a reduction in the number of devices with a significant leakage current compared to commercially available GaN substrates. Finally, we demonstrate a circular GaN substrate with a diameter of 161 mm, surpassing 6 in, grown using the Na‐flux method, making it the largest GaN substrate aside from those produced through the tiling technique.This article is protected by copyright. All rights reserved.
{"title":"Characteristics of Vertical Transistors on a GaN Substrate Fabricated via Na‐flux Method and Enlargement of the Substrate Surpassing 6 Inches","authors":"Masayuki Imanishi, S. Usami, K. Murakami, K. Okumura, Kosuke Nakamura, K. Kakinouchi, Y. Otoki, Tomio Yamashita, Naohiro Tsurumi, Satoshi Tamura, Hiroshi Ohno, Y. Okayama, Taku Fujimori, Seiji Nagai, Miki Moriyama, Yusuke Mori","doi":"10.1002/pssr.202400106","DOIUrl":"https://doi.org/10.1002/pssr.202400106","url":null,"abstract":"The Na‐flux method is expected to be a key GaN growth technique for obtainning ideal bulk GaN crystals. Herein we describe the structural quality of the latest GaN crystals grown using the Na‐flux method and, for the first time, the characteristics of a vertical transistor fabricated on a GaN substrate grown using this method. Vertical transistors exhibit normally off operation with a gate voltage threshold exceeding 2 V and a maximum drain current of 3.3 A during the on‐state operation. Additionally, it demonstrates a breakdown voltage exceeding 600 V and a low leakage current during off‐state operation. We also describe that the variation in the on‐resistance can be minimized using GaN substrates with minimal off‐angle variations. This is crucial for achieving the large‐current chips required for future demonstration of actual devices. In addition, the reverse I–V characteristics of the parasitic p–n junction diode structures indicate a reduction in the number of devices with a significant leakage current compared to commercially available GaN substrates. Finally, we demonstrate a circular GaN substrate with a diameter of 161 mm, surpassing 6 in, grown using the Na‐flux method, making it the largest GaN substrate aside from those produced through the tiling technique.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141370066","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}
Yingjie Yang, Xiaoning Zhao, Ye Tao, Ya Lin, Zhongqiang Wang
High performance microwave absorption (MA) materials are attracting growing attention to solve the expanded electromagnetic interference problems. Herein, zeolitic imidazolate organic frameworks (MOF)‐67 (ZIF‐67) are grown in‐situ on the sheet of graphene oxide (GO) through the coordination of Co2+ with oxygen functional groups. Through carbonization in an inert atmosphere, Co@carbon polyhedra (Co@CP)‐decorated reduced GO composites (Co@CP‐rGO) with a large number of heterogeneous interfaces are successfully obtained. The composites demonstrate excellent MA performance. With a filler loading of 10 wt%, the optimal minimum reflection loss (RL) of the composite can reach ‐54.6 dB. More importantly, the composites with thickness of 3.5 mm and 2.5 mm show the effective absorption bandwidth (EAB, RL < ‐10 dB) of 4.75 GHz (8.18‐12.93 GHz) and 6.56 GHz (11.44GHz‐18GHz), fully covering the X‐band and Ku‐band. It is proposed that the synergistic effect of multiple dielectric loss, magnetic loss, reflections and scattering contributes to the high MA performance.This article is protected by copyright. All rights reserved.
高性能微波吸收（MA）材料正日益受到关注，以解决扩大的电磁干扰问题。在这里，通过 Co2+ 与氧官能团的配位，在氧化石墨烯（GO）片上原位生长出沸石咪唑盐有机框架（MOF）-67（ZIF-67）。通过在惰性气氛中进行碳化，成功获得了具有大量异质界面的 Co@carbon polyhedra（Co@CP）-decorated reduced GO composites（Co@CP-rGO）。这种复合材料具有优异的 MA 性能。填料含量为 10 wt%时，复合材料的最佳最小反射损耗（RL）可达到 -54.6 dB。更重要的是，厚度分别为 3.5 mm 和 2.5 mm 的复合材料的有效吸收带宽（EAB，RL < -10dB）分别为 4.75 GHz (8.18-12.93 GHz) 和 6.56 GHz (11.44GHz-18GHz)，完全覆盖了 X 波段和 Ku 波段。本文受版权保护。本文受版权保护。
{"title":"ZIF‐67‐derived Co@Carbon polyhedra anchored on reduced graphene oxide with multiple attenuation abilities for full X‐ and Ku‐band microwave absorption","authors":"Yingjie Yang, Xiaoning Zhao, Ye Tao, Ya Lin, Zhongqiang Wang","doi":"10.1002/pssr.202400159","DOIUrl":"https://doi.org/10.1002/pssr.202400159","url":null,"abstract":"High performance microwave absorption (MA) materials are attracting growing attention to solve the expanded electromagnetic interference problems. Herein, zeolitic imidazolate organic frameworks (MOF)‐67 (ZIF‐67) are grown in‐situ on the sheet of graphene oxide (GO) through the coordination of Co2+ with oxygen functional groups. Through carbonization in an inert atmosphere, Co@carbon polyhedra (Co@CP)‐decorated reduced GO composites (Co@CP‐rGO) with a large number of heterogeneous interfaces are successfully obtained. The composites demonstrate excellent MA performance. With a filler loading of 10 wt%, the optimal minimum reflection loss (RL) of the composite can reach ‐54.6 dB. More importantly, the composites with thickness of 3.5 mm and 2.5 mm show the effective absorption bandwidth (EAB, RL < ‐10 dB) of 4.75 GHz (8.18‐12.93 GHz) and 6.56 GHz (11.44GHz‐18GHz), fully covering the X‐band and Ku‐band. It is proposed that the synergistic effect of multiple dielectric loss, magnetic loss, reflections and scattering contributes to the high MA performance.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141370928","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}
UMM4J solar cells are evaluated under different LILT conditions. The efficiency findings near Earth’s orbit (1 sun, 300 K), Jupiter (0.032 sun, 123 K), and Saturn (0.01 sun, 100 K) are 26.54%, 29.68%, and 28.27%. According to single diode model, Jsc is linear with light intensity (I), while Voc is linear with the natural logarithm of light intensity (ln(I)). Voc shows a linear relationship with temperature within the range of 150K to 300K, with a temperature coefficient of ∽ ‐7. 7 mV/K. However, Voc displays a sublinear relationship with temperature below 150K.This article is protected by copyright. All rights reserved.
{"title":"Low intensity and low temperature (LILT) effects on the Upright Metamorphic Four‐Junction (UMM4J) solar cells","authors":"Jiaming Zhou, Kelun Zhao, Yanqing Zhang, Chaoming Liu, Xinyi Li, Lijie Sun, Hongquan Zheng, Chunhua Qi, Guoliang Ma, Tianqi Wang, Mingxue Huo","doi":"10.1002/pssr.202400162","DOIUrl":"https://doi.org/10.1002/pssr.202400162","url":null,"abstract":"UMM4J solar cells are evaluated under different LILT conditions. The efficiency findings near Earth’s orbit (1 sun, 300 K), Jupiter (0.032 sun, 123 K), and Saturn (0.01 sun, 100 K) are 26.54%, 29.68%, and 28.27%. According to single diode model, Jsc is linear with light intensity (I), while Voc is linear with the natural logarithm of light intensity (ln(I)). Voc shows a linear relationship with temperature within the range of 150K to 300K, with a temperature coefficient of ∽ ‐7. 7 mV/K. However, Voc displays a sublinear relationship with temperature below 150K.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141376344","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}
G.M. Cohen, A. Majumdar, C. Cheng, A. Ray, D. Piatek, L. Gignac, C. Lavoie, A. Grun, H. Cheng, Z-L. Liu, H. Lung, H. Miyazoe, R. L. Bruce, M. BrightSky
We report a low reset current 1T1R mushroom cell phase‐change memory (PCM) device that uses fiber‐textured homostructure GeSbTe (GST) grown on highly‐oriented TiTe2 seed layer. The homostructure device outperformed the industry standard device, that uses doped polycrystalline GST, on most figures of merit. The homostructure devices were also benchmarked against superlattice PCM devices with 10 periods of 5/5nm GST/Sb2Te3 grown on the TiTe2 seed layer, and were found to have same low reset current. We also observed by TEM that the alternating layers of GST/Sb2Te3 and TiTe2/Sb2Te3 in superlattice devices is intermixed in the switched region after the devices are cycled with reset/set pulses. Additionally, when the superlattice device is left in the set state the intermixed switched region crystallinity is textured and exhibits van der Waals gaps. The superlattice PCM devices require a precise layered structure that is hard to yield on a full wafer scale. In contrast, fiber‐textured homostructure PCM cells reported here are easily manufacturable, while providing similarly low reset current and low resistance drift which makes this device suitable for analog AI computation.This article is protected by copyright. All rights reserved.
{"title":"Low reset current mushroom cell phase‐change memory (PCM) using fiber‐textured homostructure GeSbTe on highly oriented seed layer","authors":"G.M. Cohen, A. Majumdar, C. Cheng, A. Ray, D. Piatek, L. Gignac, C. Lavoie, A. Grun, H. Cheng, Z-L. Liu, H. Lung, H. Miyazoe, R. L. Bruce, M. BrightSky","doi":"10.1002/pssr.202300426","DOIUrl":"https://doi.org/10.1002/pssr.202300426","url":null,"abstract":"We report a low reset current 1T1R mushroom cell phase‐change memory (PCM) device that uses fiber‐textured homostructure GeSbTe (GST) grown on highly‐oriented TiTe2 seed layer. The homostructure device outperformed the industry standard device, that uses doped polycrystalline GST, on most figures of merit. The homostructure devices were also benchmarked against superlattice PCM devices with 10 periods of 5/5nm GST/Sb2Te3 grown on the TiTe2 seed layer, and were found to have same low reset current. We also observed by TEM that the alternating layers of GST/Sb2Te3 and TiTe2/Sb2Te3 in superlattice devices is intermixed in the switched region after the devices are cycled with reset/set pulses. Additionally, when the superlattice device is left in the set state the intermixed switched region crystallinity is textured and exhibits van der Waals gaps. The superlattice PCM devices require a precise layered structure that is hard to yield on a full wafer scale. In contrast, fiber‐textured homostructure PCM cells reported here are easily manufacturable, while providing similarly low reset current and low resistance drift which makes this device suitable for analog AI computation.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141386523","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}
UV‐ranged micro‐LEDs are being explored for numerous applications due to their high stability and power efficiency. However, previous reports have shown reduced EQE and increased leakage current due to the increase in surface‐to‐volume ratio with a decrease in the micro‐LED size. In this work, we studied the size‐related performance for UV‐A micro‐LEDs, ranging from 8 × 8 µm2 to 100 × 100 µm2. These devices exhibited reduced leakage current with the implementation of ALD based sidewall passivation. A systematic EQE comparison was performed with minimal leakage current and obtained a size‐independent on‐wafer EQE of around 5.5%. Smaller sized devices experimentally showed enhanced EQE at high current density due to their improved heat dissipation capabilities. To the best of authors’ knowledge, this is the highest reported on‐wafer EQE demonstrated in < 10 µm dimensioned 368 nm UV LEDs.This article is protected by copyright. All rights reserved.
{"title":"Demonstration of near‐size independent EQE for 368 nm UV micro‐LEDs","authors":"Guangying Wang, Shuwen Xie, Yuting Li, Wentao Zhang, Jonathan Vigen, Timothy Shih, Qinchen Lin, Jiarui Gong, Zhenqiang Ma, S. Pasayat, Chirag Gupta","doi":"10.1002/pssr.202400119","DOIUrl":"https://doi.org/10.1002/pssr.202400119","url":null,"abstract":"UV‐ranged micro‐LEDs are being explored for numerous applications due to their high stability and power efficiency. However, previous reports have shown reduced EQE and increased leakage current due to the increase in surface‐to‐volume ratio with a decrease in the micro‐LED size. In this work, we studied the size‐related performance for UV‐A micro‐LEDs, ranging from 8 × 8 µm2 to 100 × 100 µm2. These devices exhibited reduced leakage current with the implementation of ALD based sidewall passivation. A systematic EQE comparison was performed with minimal leakage current and obtained a size‐independent on‐wafer EQE of around 5.5%. Smaller sized devices experimentally showed enhanced EQE at high current density due to their improved heat dissipation capabilities. To the best of authors’ knowledge, this is the highest reported on‐wafer EQE demonstrated in < 10 µm dimensioned 368 nm UV LEDs.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141103065","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}
Tabish Aftab, Osbel Almora, J. Ferré‐Borrull, L. Marsal
This study investigates the preparation of nickel nanostructured electrodes for the enhancement of supercapacitor (SC) performance. The nanostructured electrodes were synthesized using nanoporous anodic aluminium oxide (NAA) as a template via the pulsed electrodeposition method. Structural properties were examined using field‐emission scanning electron microscopy (FESEM), while electrochemical characterization was conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results reveal that Ni nanorod arrays can be obtained embedded in the NAA matrix and with electrical contact with the aluminium substrate. On average, the rods are spaced 90 nm apart, with a diameter of 70 nm and a length of 2 µm. The Ni@NAA electrode exhibit an enlarged active area and exceptional electrochemical performance, demonstrating remarkable stability over 5000 cycles of CV at a scan rate of 50 mV·s‐1. Specific capacitance values exceeding 100 mF·cm‐2 and maximum charging times of less than 10 minutes are reported, highlighting its suitability for high‐power energy devices requiring pseudo‐supercapacitance. The study underscores the significance of nanostructured electrodes in advancing energy storage technologies and presents promising prospects for practical applications.This article is protected by copyright. All rights reserved.
{"title":"3D Nanostructured Electrodes based on Anodic Alumina Templates for Stable Pseudo‐capacitors","authors":"Tabish Aftab, Osbel Almora, J. Ferré‐Borrull, L. Marsal","doi":"10.1002/pssr.202400144","DOIUrl":"https://doi.org/10.1002/pssr.202400144","url":null,"abstract":"This study investigates the preparation of nickel nanostructured electrodes for the enhancement of supercapacitor (SC) performance. The nanostructured electrodes were synthesized using nanoporous anodic aluminium oxide (NAA) as a template via the pulsed electrodeposition method. Structural properties were examined using field‐emission scanning electron microscopy (FESEM), while electrochemical characterization was conducted through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results reveal that Ni nanorod arrays can be obtained embedded in the NAA matrix and with electrical contact with the aluminium substrate. On average, the rods are spaced 90 nm apart, with a diameter of 70 nm and a length of 2 µm. The Ni@NAA electrode exhibit an enlarged active area and exceptional electrochemical performance, demonstrating remarkable stability over 5000 cycles of CV at a scan rate of 50 mV·s‐1. Specific capacitance values exceeding 100 mF·cm‐2 and maximum charging times of less than 10 minutes are reported, highlighting its suitability for high‐power energy devices requiring pseudo‐supercapacitance. The study underscores the significance of nanostructured electrodes in advancing energy storage technologies and presents promising prospects for practical applications.This article is protected by copyright. All rights reserved.","PeriodicalId":20059,"journal":{"name":"physica status solidi (RRL) – Rapid Research Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141104432","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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