The electrode is one of the key factors that influences and controls the resistive switching characteristic of a resistive switching device. In this work, we investigated the write-once-read-many-times (WORM)-resistive switching behavior of BiFeO3 (BFO)-based devices with different top electrodes, including Pt, Ag, Cu, and Al. The WORM-resistive switching behavior has been observed in Pt/BFO/LaNiO3 (LNO), Ag/BFO/LNO, and Cu/BFO/LNO devices. In the initial high resistance state, the Pt/BFO/LNO device shows space-charge-limited current conduction due to the large Schottky barrier height at the Pt/BFO interface, while the Ag/BFO/LNO and Cu/BFO/LNO devices exhibit Schottky emission conduction due to the small barrier height at both top electrode/BFO and BFO/LNO interfaces. In the low resistance state, the metallic conduction of the Pt/BFO/LNO device is a result of the formation of conduction filaments composed of oxygen vacancies, and yet the metallic conduction of Ag/BFO/LNO and Cu/BFO/LNO devices is due to the formation of oxygen vacancies-incorporated metal conduction filaments (Ag and Cu, respectively). The observed hysteresis I-V curve of the Al/BFO/LNO device may be attributed to oxygen vacancies and defects caused by the formation of Al–O bond near the Al/BFO interface. Our results indicate that controlling an electrode is a prominent and feasible way to modulate the performance of resistive switching devices.
{"title":"Top electrode dependence of the write-once-read-many-times resistance switching in BiFeO3 films","authors":"Yajun Fu, Wei Tang, Jin Wang, Linhong Cao","doi":"10.1116/6.0002946","DOIUrl":"https://doi.org/10.1116/6.0002946","url":null,"abstract":"The electrode is one of the key factors that influences and controls the resistive switching characteristic of a resistive switching device. In this work, we investigated the write-once-read-many-times (WORM)-resistive switching behavior of BiFeO3 (BFO)-based devices with different top electrodes, including Pt, Ag, Cu, and Al. The WORM-resistive switching behavior has been observed in Pt/BFO/LaNiO3 (LNO), Ag/BFO/LNO, and Cu/BFO/LNO devices. In the initial high resistance state, the Pt/BFO/LNO device shows space-charge-limited current conduction due to the large Schottky barrier height at the Pt/BFO interface, while the Ag/BFO/LNO and Cu/BFO/LNO devices exhibit Schottky emission conduction due to the small barrier height at both top electrode/BFO and BFO/LNO interfaces. In the low resistance state, the metallic conduction of the Pt/BFO/LNO device is a result of the formation of conduction filaments composed of oxygen vacancies, and yet the metallic conduction of Ag/BFO/LNO and Cu/BFO/LNO devices is due to the formation of oxygen vacancies-incorporated metal conduction filaments (Ag and Cu, respectively). The observed hysteresis I-V curve of the Al/BFO/LNO device may be attributed to oxygen vacancies and defects caused by the formation of Al–O bond near the Al/BFO interface. Our results indicate that controlling an electrode is a prominent and feasible way to modulate the performance of resistive switching devices.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135253522","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}
Metal-pattern formation using vacuum evaporation is a critical process from basic research to industrial mass-production. Selective metal deposition using metal-atom desorption from an organic surface is a promising metal-patterning method by maskless vacuum deposition. In this study, we demonstrate metal-pattern formation by maskless deposition for various metal species using a vacuum-depositable and printable perfluoropolyether (PFPE) based material. A PFPE-based film has a low dispersion component of surface free energy and surface softness, and its surface has the ability to efficiently desorb for various metals. This method, which enables metal-pattern formation using maskless vacuum deposition for a variety of metal species with a high melting point and low intrinsic vapor pressure, including Ag, Cr, and Ni, can be applied to such applications as electrode-pattern formations.
{"title":"Metal-pattern preparation based on selective deposition using soft organofluorine surfaces","authors":"Tsuyoshi Tsujioka","doi":"10.1116/6.0002832","DOIUrl":"https://doi.org/10.1116/6.0002832","url":null,"abstract":"Metal-pattern formation using vacuum evaporation is a critical process from basic research to industrial mass-production. Selective metal deposition using metal-atom desorption from an organic surface is a promising metal-patterning method by maskless vacuum deposition. In this study, we demonstrate metal-pattern formation by maskless deposition for various metal species using a vacuum-depositable and printable perfluoropolyether (PFPE) based material. A PFPE-based film has a low dispersion component of surface free energy and surface softness, and its surface has the ability to efficiently desorb for various metals. This method, which enables metal-pattern formation using maskless vacuum deposition for a variety of metal species with a high melting point and low intrinsic vapor pressure, including Ag, Cr, and Ni, can be applied to such applications as electrode-pattern formations.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135346983","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}
Capacitively coupled plasma (CCP) tools are crucial for etching, deposition, and cleaning processes in the semiconductor industry. A comprehensive understanding of their discharge characteristics is vital for the advancement of chip processing technology. In this study, the influence of external circuitry on the breakdown process was investigated under the CF4 discharge system, with a particular focus on challenges presented by the nonlinear nature of the plasma. The results demonstrated that the external circuit significantly affects the discharge process by altering the electric field distribution as well as modifying the electron density and temperature of the plasma. By incorporating the matching circuit, stable discharge was achieved at reduced voltage levels. During breakdown, a substantial increase in the capacitance of the discharge chamber is induced by the formation of the sheath, which alters the amplitude of the electrical signal within the external circuit. The breakdown characteristics are significantly influenced by the capacitance of the matching network. Breakdowns with distinctive characteristics can be achieved by selectively choosing different capacitors. Furthermore, a shift in the CF4 discharge mode at different pressures under the external circuit model and the alteration in the discharge mode affect the electrical properties of the plasma in the matched circuit. These findings could be used to optimize the discharge of CCP and its applications, including surface treatment, material synthesis, and environmental remediation.
{"title":"Influence of external circuitry on CF4 breakdown process in capacitively coupled plasma","authors":"Zhaoyu Chen, Jingwen Xu, Hongyu Wang, Hao Wu, Wei Jiang, Ya Zhang","doi":"10.1116/5.0161552","DOIUrl":"https://doi.org/10.1116/5.0161552","url":null,"abstract":"Capacitively coupled plasma (CCP) tools are crucial for etching, deposition, and cleaning processes in the semiconductor industry. A comprehensive understanding of their discharge characteristics is vital for the advancement of chip processing technology. In this study, the influence of external circuitry on the breakdown process was investigated under the CF4 discharge system, with a particular focus on challenges presented by the nonlinear nature of the plasma. The results demonstrated that the external circuit significantly affects the discharge process by altering the electric field distribution as well as modifying the electron density and temperature of the plasma. By incorporating the matching circuit, stable discharge was achieved at reduced voltage levels. During breakdown, a substantial increase in the capacitance of the discharge chamber is induced by the formation of the sheath, which alters the amplitude of the electrical signal within the external circuit. The breakdown characteristics are significantly influenced by the capacitance of the matching network. Breakdowns with distinctive characteristics can be achieved by selectively choosing different capacitors. Furthermore, a shift in the CF4 discharge mode at different pressures under the external circuit model and the alteration in the discharge mode affect the electrical properties of the plasma in the matched circuit. These findings could be used to optimize the discharge of CCP and its applications, including surface treatment, material synthesis, and environmental remediation.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135346984","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}
Polycrystalline α-tantalum (110) films deposited on the c-plane sapphire substrate by sputtering are used in superconducting qubits nowadays. However, these films always occasionally form other structures, such as α-tantalum (111) grains and β-tantalum grains. To improve the film quality, we investigate the growth of α-tantalum (110) films on the a-plane sapphire substrate under varying conditions by molecular beam epitaxy technology. The optimized α-tantalum (110) film is a single crystal, with a smooth surface and atomically flat metal–substrate interface. The film with thickness of 30 nm shows a Tc of 4.12 K and a high residual resistance ratio of 9.53. The quarter wavelength coplanar waveguide resonators fabricated with the 150 nm optimized α-tantalum (110) film exhibit intrinsic quality factor of over one million under single photon excitation at millikelvin temperature.
{"title":"Investigation of the deposition of α-tantalum (110) films on a-plane sapphire substrate by molecular beam epitaxy for superconducting circuit","authors":"Haolin Jia, Boyi zhou, Tao Wang, Yanfu Wu, Lina Yang, Zengqian Ding, Shuming Li, Xiao Cai, Kanglin Xiong, Jiagui Feng","doi":"10.1116/6.0002886","DOIUrl":"https://doi.org/10.1116/6.0002886","url":null,"abstract":"Polycrystalline α-tantalum (110) films deposited on the c-plane sapphire substrate by sputtering are used in superconducting qubits nowadays. However, these films always occasionally form other structures, such as α-tantalum (111) grains and β-tantalum grains. To improve the film quality, we investigate the growth of α-tantalum (110) films on the a-plane sapphire substrate under varying conditions by molecular beam epitaxy technology. The optimized α-tantalum (110) film is a single crystal, with a smooth surface and atomically flat metal–substrate interface. The film with thickness of 30 nm shows a Tc of 4.12 K and a high residual resistance ratio of 9.53. The quarter wavelength coplanar waveguide resonators fabricated with the 150 nm optimized α-tantalum (110) film exhibit intrinsic quality factor of over one million under single photon excitation at millikelvin temperature.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135890036","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}
We report on the development of a chemical mechanical planarization (CMP) process for thick damascene Ta structures with pattern feature sizes down to 100 nm. This CMP process is the core of the fabrication sequence for scalable superconducting integrated circuits at a 300 mm wafer scale. This work has established the elements of various CMP-related design rules that can be followed by a designer for the layout of circuits that include Ta-based coplanar waveguide resonators, capacitors, and interconnects for tantalum-based qubits and single flux quantum circuits. The fabrication of these structures utilizes a 193 nm optical lithography along with 300 mm process tools for dielectric deposition, reactive ion etch, wet-clean, CMP, and in-line metrology—all tools typical for a 300 mm wafer CMOS foundry. Theprocess development was guided by measurements of the physical and electrical characteristics of the planarized structures. Physical characterization such as atomic force microscopy across the 300 mm wafer surface showed that local topography was less than 5 nm. Electrical characterization confirmed low leakage at room temperature, and less than 12% within wafer sheet resistance variation for damascene Ta line widths ranging from 100 nm to 3 μm. Run-to-run reproducibility was also evaluated. Effects of process integration choices including the deposited thickness of Ta are discussed.
{"title":"Chemical mechanical planarization for Ta-based superconducting quantum devices","authors":"Bhatia, Ekta, Kar, Soumen, Nalaskowski, Jakub, Vo, Tuan, Olson, Stephen, Frost, Hunter, Mucci, John, Martinick, Brian, Hung, Pui Yee, Wells, Ilyssa, Schujman, Sandra, Rao, Satyavolu S. Papa","doi":"10.1116/6.0002586","DOIUrl":"https://doi.org/10.1116/6.0002586","url":null,"abstract":"We report on the development of a chemical mechanical planarization (CMP) process for thick damascene Ta structures with pattern feature sizes down to 100 nm. This CMP process is the core of the fabrication sequence for scalable superconducting integrated circuits at a 300 mm wafer scale. This work has established the elements of various CMP-related design rules that can be followed by a designer for the layout of circuits that include Ta-based coplanar waveguide resonators, capacitors, and interconnects for tantalum-based qubits and single flux quantum circuits. The fabrication of these structures utilizes a 193 nm optical lithography along with 300 mm process tools for dielectric deposition, reactive ion etch, wet-clean, CMP, and in-line metrology—all tools typical for a 300 mm wafer CMOS foundry. Theprocess development was guided by measurements of the physical and electrical characteristics of the planarized structures. Physical characterization such as atomic force microscopy across the 300 mm wafer surface showed that local topography was less than 5 nm. Electrical characterization confirmed low leakage at room temperature, and less than 12% within wafer sheet resistance variation for damascene Ta line widths ranging from 100 nm to 3 μm. Run-to-run reproducibility was also evaluated. Effects of process integration choices including the deposited thickness of Ta are discussed.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135693608","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}
Jun Zhang, K. McNicholas, S. Balaz, Zhaobing Zeng, D. Schlom, L. Brillson
Intrinsic point defects are commonly present in and can strongly affect the electronic properties of complex oxides and their interfaces. The near- and subsurface characterization techniques, depth-resolved cathodoluminescence spectroscopy and surface photovoltage spectroscopy, can measure the density distributions, energy levels, and optical transitions of intrinsic point defects in complex oxides on a near-nanometer scale. These measurements on SrTiO3, BaTiO3, and related materials reveal the sensitivity of intrinsic point defects to growth temperature, mechanical strain, crystal orientation, and chemical interactions. Spatial redistribution of these defects can vary significantly near surfaces and interfaces and can have strong electronic effects. The combination of these deep level spectroscopies along with other advanced characterization techniques provides an avenue to further expand the understanding and control of complex oxide defects in general.
{"title":"Deep level defect spectroscopies of complex oxide surfaces and interfaces","authors":"Jun Zhang, K. McNicholas, S. Balaz, Zhaobing Zeng, D. Schlom, L. Brillson","doi":"10.1116/6.0001339","DOIUrl":"https://doi.org/10.1116/6.0001339","url":null,"abstract":"Intrinsic point defects are commonly present in and can strongly affect the electronic properties of complex oxides and their interfaces. The near- and subsurface characterization techniques, depth-resolved cathodoluminescence spectroscopy and surface photovoltage spectroscopy, can measure the density distributions, energy levels, and optical transitions of intrinsic point defects in complex oxides on a near-nanometer scale. These measurements on SrTiO3, BaTiO3, and related materials reveal the sensitivity of intrinsic point defects to growth temperature, mechanical strain, crystal orientation, and chemical interactions. Spatial redistribution of these defects can vary significantly near surfaces and interfaces and can have strong electronic effects. The combination of these deep level spectroscopies along with other advanced characterization techniques provides an avenue to further expand the understanding and control of complex oxide defects in general.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88468715","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}
Clarence Chan, Shunya Namiki, J. Hite, M. Mastro, S. Qadri, Xiuling Li
Metal-assisted chemical etching is a plasma-free open-circuit anisotropic etching method that produces high aspect ratio structures in various semiconductors. Here, for the first time, we demonstrate the formation of ordered micropillar arrays of homoepitaxial GaN, using photo-enhanced MacEtch with patterned platinum films as the catalyst. The GaN etching rate and morphology as a function of etching chemistry, growth method, and doping conditions are investigated, and the etch mechanism is analyzed. Etch rates and surface smoothness are found to increase with the Si-doping level in GaN, approaching those achieved by reactive ion etching and photoelectrochemical etching. Spatially resolved photoluminescence shows no degradation in near band edge emission and no newly generated defect peaks, as expected due to the high energy ion free nature. This approach can also potentially be applied to InGaN and AlGaN by tuning the etch chemistry and illumination wavelength, enabling a facile and scalable processing of 3D III-nitride based electronic and optoelectronic devices such as μLEDs and finFETs.
金属辅助化学刻蚀是一种无等离子体开路各向异性刻蚀方法，可在各种半导体中产生高纵横比结构。在这里，我们首次展示了有序微柱阵列的形成同外延GaN，使用光增强MacEtch与图案铂薄膜作为催化剂。研究了GaN的蚀刻速率和形貌与蚀刻化学、生长方式和掺杂条件的关系，并分析了其蚀刻机理。随着氮化镓中硅掺杂水平的提高，其蚀刻速率和表面光滑度也随之提高，接近于反应离子蚀刻和光电化学蚀刻所达到的水平。空间分辨光致发光在近带边缘发射没有退化，也没有新的缺陷峰产生，这是由于高能量的无离子特性所导致的。这种方法也可以通过调整蚀刻化学和照明波长来潜在地应用于InGaN和AlGaN，从而实现基于3D iii -氮化物的电子和光电子器件(如μ led和finfet)的简单和可扩展处理。
{"title":"Homoepitaxial GaN micropillar array by plasma-free photo-enhanced metal-assisted chemical etching","authors":"Clarence Chan, Shunya Namiki, J. Hite, M. Mastro, S. Qadri, Xiuling Li","doi":"10.1116/6.0001231","DOIUrl":"https://doi.org/10.1116/6.0001231","url":null,"abstract":"Metal-assisted chemical etching is a plasma-free open-circuit anisotropic etching method that produces high aspect ratio structures in various semiconductors. Here, for the first time, we demonstrate the formation of ordered micropillar arrays of homoepitaxial GaN, using photo-enhanced MacEtch with patterned platinum films as the catalyst. The GaN etching rate and morphology as a function of etching chemistry, growth method, and doping conditions are investigated, and the etch mechanism is analyzed. Etch rates and surface smoothness are found to increase with the Si-doping level in GaN, approaching those achieved by reactive ion etching and photoelectrochemical etching. Spatially resolved photoluminescence shows no degradation in near band edge emission and no newly generated defect peaks, as expected due to the high energy ion free nature. This approach can also potentially be applied to InGaN and AlGaN by tuning the etch chemistry and illumination wavelength, enabling a facile and scalable processing of 3D III-nitride based electronic and optoelectronic devices such as μLEDs and finFETs.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88958552","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}
Moon-Sic Jung, Dongwoo Kim, Hojoon Lim, M. Seo, Geonhwa Kim, Luciana Ramirez, F. Bournel, J. Gallet, Ki-jeong Kim, B. Mun
Utilizing ambient pressure x-ray photoelectron spectroscopy, the surface segregation and the oxidation dynamics of platinum (Pt)-3d transition metal (M) alloys, Pt3M (M = Ti, V), are investigated. Under oxygen-rich conditions, i.e., P(CO)/P(O2) = 0.1, Pt3V surface forms Pt skin layer while Pt3Ti shows the presence of both Ti and Pt atoms. As temperature increases to 450 K, V atoms make surface segregation to form oxide while Ti atoms start to form various Ti oxides (Ti2O3 and TiOx) on the surface. When CO oxidation occurs at 600 K, the oxidation continues on both surfaces of Pt3M (M = Ti, V), showing the enhancement of TiOx for Pt3Ti and V2O5 and VOx for Pt3V. Also, during CO oxidation, a sign of pure metallic Pt state is found at Pt 4f spectra in both surfaces, suggesting the redistribution of electrons from the transition metals during the oxide formation.
{"title":"Surface study of Pt-3d transition metal alloys, Pt3M (M = Ti, V), under CO oxidation reaction with ambient pressure x-ray photoelectron spectroscopy","authors":"Moon-Sic Jung, Dongwoo Kim, Hojoon Lim, M. Seo, Geonhwa Kim, Luciana Ramirez, F. Bournel, J. Gallet, Ki-jeong Kim, B. Mun","doi":"10.1116/6.0001194","DOIUrl":"https://doi.org/10.1116/6.0001194","url":null,"abstract":"Utilizing ambient pressure x-ray photoelectron spectroscopy, the surface segregation and the oxidation dynamics of platinum (Pt)-3d transition metal (M) alloys, Pt3M (M = Ti, V), are investigated. Under oxygen-rich conditions, i.e., P(CO)/P(O2) = 0.1, Pt3V surface forms Pt skin layer while Pt3Ti shows the presence of both Ti and Pt atoms. As temperature increases to 450 K, V atoms make surface segregation to form oxide while Ti atoms start to form various Ti oxides (Ti2O3 and TiOx) on the surface. When CO oxidation occurs at 600 K, the oxidation continues on both surfaces of Pt3M (M = Ti, V), showing the enhancement of TiOx for Pt3Ti and V2O5 and VOx for Pt3V. Also, during CO oxidation, a sign of pure metallic Pt state is found at Pt 4f spectra in both surfaces, suggesting the redistribution of electrons from the transition metals during the oxide formation.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83096373","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}
Conventional solar-blind photodetectors based on the conduction of photoexcited carriers are energy inefficient owing to the power dissipation caused by a resistive sensing mechanism and the narrow bandgap energy of the photon-absorbing layer. Herein, we demonstrate the energy-efficient capacitive sensing of deep-UV wavelengths by integrating an intrinsically solar-blind ultrawide bandgap (UWBG) β-Ga2O3 semiconductor with UV-transparent and conductive graphene electrode. A UWBG β-Ga2O3 eliminates the requirement of a solar-blind deep-UV bandpass filter. The high optical transmittance of the graphene enables UV-C light to be absorbed in the underlying β-Ga2O3, thereby facilitating carrier transport between the graphene electrode and β-Ga2O3. A capacitance change under UV-C excitation is observed, along with excellent reproductivity and spectral selectivity at various frequencies and bias conditions; the sensing performance improves with an increase in frequency. The average power dissipation of the fabricated photodetector in the stand-by (dark) and active (UV-C illumination) modes is 37.7 and 53.3 μW, respectively. Overall, this work introduces a new strategy for developing next-generation compact and energy-efficient solar-blind photodetectors.
{"title":"Capacitive β-Ga2O3 solar-blind photodetector with graphene electrode","authors":"A-Hyun Kim, Geonyeop Lee, Jihyun Kim","doi":"10.1116/6.0001217","DOIUrl":"https://doi.org/10.1116/6.0001217","url":null,"abstract":"Conventional solar-blind photodetectors based on the conduction of photoexcited carriers are energy inefficient owing to the power dissipation caused by a resistive sensing mechanism and the narrow bandgap energy of the photon-absorbing layer. Herein, we demonstrate the energy-efficient capacitive sensing of deep-UV wavelengths by integrating an intrinsically solar-blind ultrawide bandgap (UWBG) β-Ga2O3 semiconductor with UV-transparent and conductive graphene electrode. A UWBG β-Ga2O3 eliminates the requirement of a solar-blind deep-UV bandpass filter. The high optical transmittance of the graphene enables UV-C light to be absorbed in the underlying β-Ga2O3, thereby facilitating carrier transport between the graphene electrode and β-Ga2O3. A capacitance change under UV-C excitation is observed, along with excellent reproductivity and spectral selectivity at various frequencies and bias conditions; the sensing performance improves with an increase in frequency. The average power dissipation of the fabricated photodetector in the stand-by (dark) and active (UV-C illumination) modes is 37.7 and 53.3 μW, respectively. Overall, this work introduces a new strategy for developing next-generation compact and energy-efficient solar-blind photodetectors.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80964317","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}
Cu-Co-Mn spinel oxide thin films are deposited by reactive magnetron sputtering. The x-ray diffraction (XRD) spectrum suggests a nanocrystalline spinel film when sputtered at ≈465 °C. In-line scanning tunneling microscopy confirms nanometric sized grains in the order of 5–10 nm, which then form larger agglomerations of 30–70 nm as observed by scanning electron microscopy. The pristine sample surfaces are characterized by in-line UV photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). From UPS He I and He II spectra, a valence band edge of 0.38 eV, compatible with a bandgap of ≈0.8 eV, is determined. XPS infers Cu2+, Co3+, and Mn3+ as dominant, thus, fitting well the general spinel formula A2+B23+O42−. The elemental quantification based on XPS core-level peak integration indicates some Cu enrichment and a secondary CuO phase formation at the spinel surface that is congruent with the XRD results where peaks associated with tenorite CuO are also identified. The partially filled 3d bands make the Cu-Co-Mn oxides a promising candidate for selective solar absorbers. The measured spectral reflectance of CuCoMnOx//SiO2 double layer yields a solar absorptance of 0.8 and thermal emittance of 0.05. The coating durability and thermal stability in the air have been confirmed by accelerated aging tests at 270 °C for a duration of 600 h.
{"title":"In-line electronic and structural characterization of reactively sputtered Cu-Co-Mn black spinel oxides","authors":"A. Krammer, M. Lagier, A. Schüler","doi":"10.1116/6.0001120","DOIUrl":"https://doi.org/10.1116/6.0001120","url":null,"abstract":"Cu-Co-Mn spinel oxide thin films are deposited by reactive magnetron sputtering. The x-ray diffraction (XRD) spectrum suggests a nanocrystalline spinel film when sputtered at ≈465 °C. In-line scanning tunneling microscopy confirms nanometric sized grains in the order of 5–10 nm, which then form larger agglomerations of 30–70 nm as observed by scanning electron microscopy. The pristine sample surfaces are characterized by in-line UV photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). From UPS He I and He II spectra, a valence band edge of 0.38 eV, compatible with a bandgap of ≈0.8 eV, is determined. XPS infers Cu2+, Co3+, and Mn3+ as dominant, thus, fitting well the general spinel formula A2+B23+O42−. The elemental quantification based on XPS core-level peak integration indicates some Cu enrichment and a secondary CuO phase formation at the spinel surface that is congruent with the XRD results where peaks associated with tenorite CuO are also identified. The partially filled 3d bands make the Cu-Co-Mn oxides a promising candidate for selective solar absorbers. The measured spectral reflectance of CuCoMnOx//SiO2 double layer yields a solar absorptance of 0.8 and thermal emittance of 0.05. The coating durability and thermal stability in the air have been confirmed by accelerated aging tests at 270 °C for a duration of 600 h.","PeriodicalId":17571,"journal":{"name":"Journal of Vacuum Science and Technology","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77292650","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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