This work presents a compact ion-pump that utilizes pyroelectricity for ionization of ambient molecules. The pyroelectric ionization is realized by heating a lithium niobate (LiNbO3) crystal with low voltage resistive heating (10 V drive voltage, 0.5 W Joule heating) to generate a high voltage across the poled surface of the crystal. Pyroelectrically generated electrons from the polarized surface of the crystal are accelerated using an electric field generated by both the crystal and external titanium (Ti) electrodes biased at ±300 V, which results in the ionization of molecules in the chamber. The low collector current in the pA range ensures that the power consumed due to ionization current is lower than the LiNbO3 heating power. The ionized gas molecules are accelerated toward the Ti collector electrodes where they are implanted owing to large acceleration produced by the collector electrodes. The system is configured as a sputter pump for gettering ions to reduce chamber pressure from the baseline value of 1.4 μTorr with just the external pump to 1.1 μTorr by incorporating the LiNbO3 pump. The proof-of-concept of the pyroelectric pumping mechanism is demonstrated using a 140 cm3 stainless steel vacuum chamber, with supplementary turbomolecular and diaphragm pumps and demonstrates that a 50 s thermal cycling of the crystal is optimal for the ion-pump. Pumping action was measured with a Pirani gauge and a hot cathode ion gauge. Analytical modeling and experimental results for pumping speed calculations showed a good match during high-pressure pumping.
{"title":"Pyroelectric lithium niobate electron emission-based ion-pump","authors":"K. Vinayakumar, V. Gund, A. Lal","doi":"10.1116/6.0000882","DOIUrl":"https://doi.org/10.1116/6.0000882","url":null,"abstract":"This work presents a compact ion-pump that utilizes pyroelectricity for ionization of ambient molecules. The pyroelectric ionization is realized by heating a lithium niobate (LiNbO3) crystal with low voltage resistive heating (10 V drive voltage, 0.5 W Joule heating) to generate a high voltage across the poled surface of the crystal. Pyroelectrically generated electrons from the polarized surface of the crystal are accelerated using an electric field generated by both the crystal and external titanium (Ti) electrodes biased at ±300 V, which results in the ionization of molecules in the chamber. The low collector current in the pA range ensures that the power consumed due to ionization current is lower than the LiNbO3 heating power. The ionized gas molecules are accelerated toward the Ti collector electrodes where they are implanted owing to large acceleration produced by the collector electrodes. The system is configured as a sputter pump for gettering ions to reduce chamber pressure from the baseline value of 1.4 μTorr with just the external pump to 1.1 μTorr by incorporating the LiNbO3 pump. The proof-of-concept of the pyroelectric pumping mechanism is demonstrated using a 140 cm3 stainless steel vacuum chamber, with supplementary turbomolecular and diaphragm pumps and demonstrates that a 50 s thermal cycling of the crystal is optimal for the ion-pump. Pumping action was measured with a Pirani gauge and a hot cathode ion gauge. Analytical modeling and experimental results for pumping speed calculations showed a good match during high-pressure pumping.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79327636","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}
Qing Liu, Dong Zhou, Weizong Xu, Dunjun Chen, F. Ren, Rong Zhang, Youdou Zheng, Hai Lu
In this work, a large size x-ray detector with a 25 mm2 active area is demonstrated based on a thick 4H-SiC p-i-n structure. The detector exhibits obvious merits of high photon sensitivity over 4 × 104 μC Gy−1 cm−2, good photon-response linearity, and high-temperature operation compatibility. Meanwhile, due to the ultralow leakage current level achieved, single photon detection performance for x-ray photons is further realized with energy resolutions of 1.1 and 4.9 keV at 5.9 and 59.5 keV, respectively. This work thus suggests the significant potentials of wide-bandgap SiC semiconductor for photon-resolved x-ray detection in a harsh environment.
{"title":"High sensitivity x-ray detectors based on 4H-SiC p-i-n structure with 80 μm thick intrinsic layer","authors":"Qing Liu, Dong Zhou, Weizong Xu, Dunjun Chen, F. Ren, Rong Zhang, Youdou Zheng, Hai Lu","doi":"10.1116/6.0000829","DOIUrl":"https://doi.org/10.1116/6.0000829","url":null,"abstract":"In this work, a large size x-ray detector with a 25 mm2 active area is demonstrated based on a thick 4H-SiC p-i-n structure. The detector exhibits obvious merits of high photon sensitivity over 4 × 104 μC Gy−1 cm−2, good photon-response linearity, and high-temperature operation compatibility. Meanwhile, due to the ultralow leakage current level achieved, single photon detection performance for x-ray photons is further realized with energy resolutions of 1.1 and 4.9 keV at 5.9 and 59.5 keV, respectively. This work thus suggests the significant potentials of wide-bandgap SiC semiconductor for photon-resolved x-ray detection in a harsh environment.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90144651","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}
A model of electron gas scattering at surface inhomogeneities was developed and applied to describe a surface roughness influence on the electrical resistivity of thin metallic films. The model is developed to be simple enough for fast calculations without detailed investigation of surface topology. The film’s shape is assumed to be described by the average thickness, the surface rms, and the correlation length. The scattering mechanism corresponds to electrical potential changes caused by inhomogeneities. It was found that the electrical resistivity of thin films increases with the increase of the roughness of surface for films of any thickness, whereas the law of this effect depends on film’s thickness. Basing on the developed model, formulas for the electrical resistivity as a function of the roughness rms and the correlation length in cases of thick enough, thin, and extremely thin films have been obtained and discussed with comparison to other models already in literature and experimental data.
{"title":"Theoretical model for fast calculations of the electrical resistivity of thin metallic films with rough surfaces","authors":"A. A. Pribylov","doi":"10.1116/6.0000781","DOIUrl":"https://doi.org/10.1116/6.0000781","url":null,"abstract":"A model of electron gas scattering at surface inhomogeneities was developed and applied to describe a surface roughness influence on the electrical resistivity of thin metallic films. The model is developed to be simple enough for fast calculations without detailed investigation of surface topology. The film’s shape is assumed to be described by the average thickness, the surface rms, and the correlation length. The scattering mechanism corresponds to electrical potential changes caused by inhomogeneities. It was found that the electrical resistivity of thin films increases with the increase of the roughness of surface for films of any thickness, whereas the law of this effect depends on film’s thickness. Basing on the developed model, formulas for the electrical resistivity as a function of the roughness rms and the correlation length in cases of thick enough, thin, and extremely thin films have been obtained and discussed with comparison to other models already in literature and experimental data.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82286809","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}
Aluminum gallium nitride (AlGaN) nanowires have become an emerging approach for semiconductor deep ultraviolet light-emitting devices. To further improve the device performance, it is critical to understand the optical quality of AlGaN nanowires. However, today, the room-temperature internal quantum efficiency (IQE) of AlGaN nanowires is predominantly analyzed by the temperature-dependent photoluminescence (PL) approach under one excitation power or taking the PL intensity ratio at the room temperature and low temperature with different excitation powers. In both cases, one needs to assume the low temperature IQE to be 100%, which is not always valid, in particular when the excitation power changes at the low temperature. In this work, we study the room-temperature IQE of AlGaN nanowires through the detailed excitation power-dependent PL experiments and theoretical analysis. This allows us to derive the intrinsic room-temperature IQE of AlGaN nanowires as a function of the excitation power. It is found that for an Al content in the range of 22%–54%, the IQE of all samples increases as the excitation increases, followed by an efficiency droop. Moreover, comparing different samples, the IQE at low excitations increases as the Al content increases, whereas the peak IQE reduces from 73% to 56% as the Al content increases. The underlying mechanisms are also discussed in this paper.
{"title":"Intrinsic excitation-dependent room-temperature internal quantum efficiency of AlGaN nanowires with varying Al contents","authors":"Jiaying Lu, Y. Zhong, Songrui Zhao","doi":"10.1116/6.0000763","DOIUrl":"https://doi.org/10.1116/6.0000763","url":null,"abstract":"Aluminum gallium nitride (AlGaN) nanowires have become an emerging approach for semiconductor deep ultraviolet light-emitting devices. To further improve the device performance, it is critical to understand the optical quality of AlGaN nanowires. However, today, the room-temperature internal quantum efficiency (IQE) of AlGaN nanowires is predominantly analyzed by the temperature-dependent photoluminescence (PL) approach under one excitation power or taking the PL intensity ratio at the room temperature and low temperature with different excitation powers. In both cases, one needs to assume the low temperature IQE to be 100%, which is not always valid, in particular when the excitation power changes at the low temperature. In this work, we study the room-temperature IQE of AlGaN nanowires through the detailed excitation power-dependent PL experiments and theoretical analysis. This allows us to derive the intrinsic room-temperature IQE of AlGaN nanowires as a function of the excitation power. It is found that for an Al content in the range of 22%–54%, the IQE of all samples increases as the excitation increases, followed by an efficiency droop. Moreover, comparing different samples, the IQE at low excitations increases as the Al content increases, whereas the peak IQE reduces from 73% to 56% as the Al content increases. The underlying mechanisms are also discussed in this paper.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91201460","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}
The Schwarz–Christoffel transformation is used to analytically evaluate the field enhancement factor close to the apex of two-stage conducting structures consisting of a vertical line centered on the top of an isosceles trapezoidal protrusion on an infinite line. This way the validity of the Schottky conjecture (SC) is assessed for different ratios involving the dimensions of the system, which is expected to model quasi-one-dimensional structures, such as nanotubes, on the top of multistage structures used in different scientific and technological applications. The results obtained in this work suggest that the SC remains a good approximation beyond the region in which it is usually expected to be valid.
{"title":"About the robustness of Schottky conjecture when quasi-one-dimensional stages are present","authors":"Edgar Marcelino de Carvalho Neto","doi":"10.1116/6.0000727","DOIUrl":"https://doi.org/10.1116/6.0000727","url":null,"abstract":"The Schwarz–Christoffel transformation is used to analytically evaluate the field enhancement factor close to the apex of two-stage conducting structures consisting of a vertical line centered on the top of an isosceles trapezoidal protrusion on an infinite line. This way the validity of the Schottky conjecture (SC) is assessed for different ratios involving the dimensions of the system, which is expected to model quasi-one-dimensional structures, such as nanotubes, on the top of multistage structures used in different scientific and technological applications. The results obtained in this work suggest that the SC remains a good approximation beyond the region in which it is usually expected to be valid.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89843102","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 studied the formation of ideally ordered nanoporous zirconia by anodizing Zr having a texturing pattern. A texturing pattern was formed on a Zr surface by peeling off a sputtered zirconium film from a metal (Ni) mold having an ordered array of convexes. In contrast to texturing by nanoimprinting, the present texturing process never requires the pressing of a mold onto the Zr surface. During the anodization of Zr that has a texturing pattern on its surface, which is an ideally ordered array of concaves, each concave acted as a starting point of the formation of nanoholes. By the present process, porous anodic zirconia having an ideally ordered array of nanoholes was obtained. The interval between nanoholes in the porous anodic zirconia agreed with the texturing pattern.
{"title":"Formation of ideally ordered porous anodic zirconia by anodization of vacuum deposited Zr on molds","authors":"T. Kondo, Touko Tamura, T. Yanagishita, H. Masuda","doi":"10.1116/6.0000864","DOIUrl":"https://doi.org/10.1116/6.0000864","url":null,"abstract":"We studied the formation of ideally ordered nanoporous zirconia by anodizing Zr having a texturing pattern. A texturing pattern was formed on a Zr surface by peeling off a sputtered zirconium film from a metal (Ni) mold having an ordered array of convexes. In contrast to texturing by nanoimprinting, the present texturing process never requires the pressing of a mold onto the Zr surface. During the anodization of Zr that has a texturing pattern on its surface, which is an ideally ordered array of concaves, each concave acted as a starting point of the formation of nanoholes. By the present process, porous anodic zirconia having an ideally ordered array of nanoholes was obtained. The interval between nanoholes in the porous anodic zirconia agreed with the texturing pattern.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84133789","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}
Mazen A. Madanat, Mohammad Al Share, Mohammad M. Allaham, M. Mousa
This study introduces an easy methodology to test and analyze experimental field electron emission current-voltage data from metallic single-tip emitters; this novel and easy methodology is called the Murphy–Good plots. Tungsten electron emitters were used as an example and were prepared by the electrochemical etching process. The current-voltage characteristics are obtained in high vacuum levels and using a traditional field emission microscope. Murphy–Good plots are used to apply the well-known field electron emission orthodoxy test to the experimental data and then to extract the emitters’ characterization parameters if the test is passed. The novelty in using this type of plots lies in its independency on any correction factors, unlike the traditional Fowler–Nordheim and Millikan–Lauritsen plots, in addition to its simple theoretical form. The results are calculated using a simple web tool that applies the field electron emission orthodoxy test to any type of the current-voltage analysis plots and then to extract the characterization parameters of the emitters.
{"title":"Information extraction from Murphy–Good plots of tungsten field electron emitters","authors":"Mazen A. Madanat, Mohammad Al Share, Mohammad M. Allaham, M. Mousa","doi":"10.1116/6.0000803","DOIUrl":"https://doi.org/10.1116/6.0000803","url":null,"abstract":"This study introduces an easy methodology to test and analyze experimental field electron emission current-voltage data from metallic single-tip emitters; this novel and easy methodology is called the Murphy–Good plots. Tungsten electron emitters were used as an example and were prepared by the electrochemical etching process. The current-voltage characteristics are obtained in high vacuum levels and using a traditional field emission microscope. Murphy–Good plots are used to apply the well-known field electron emission orthodoxy test to the experimental data and then to extract the emitters’ characterization parameters if the test is passed. The novelty in using this type of plots lies in its independency on any correction factors, unlike the traditional Fowler–Nordheim and Millikan–Lauritsen plots, in addition to its simple theoretical form. The results are calculated using a simple web tool that applies the field electron emission orthodoxy test to any type of the current-voltage analysis plots and then to extract the characterization parameters of the emitters.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77677628","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}
For more than two decades, carbon nanotubes (CNTs) have shown great potential for a wide range of applications. Several methods are known to synthesize CNTs, though only a few of them are able to produce good quality and economically available CNTs. Chemical vapor deposition (CVD) is one of those methods that produce economically feasible and good quality CNTs onto specific substrates, even with nanopatterning. However, growing CNTs by CVD at temperatures below 700 °C remained a long-time challenge, as this meant keeping a host of low-melting materials out of bounds for direct CNT growth on them. In this work, CNTs have been synthesized directly onto a low-melting, conducting substrate, aluminum, by thermal CVD, at a temperature as low as 550 °C and up to as high as 650 °C (just below the melting point of aluminum). The diameters of the grown CNTs were observed to be influenced by process parameters, e.g., temperature and pressure. The effect of synthesis parameters on CNT diameters was verified by scanning electron microscopy and transmission electron microscopy. The quality of the CNTs was checked by Raman spectroscopy, selected area electron diffraction pattern of transmission electron microscopy, and XPS. It was observed that an increase in temperature and pressure had a significant effect on the diameters of the CNTs. Randomly entangled CNTs were measured to have an average diameter of 28 nm at 550 °C and one atmospheric (760 Torr) pressure, whereas it was observed to be 78 nm at a temperature of 650 °C and pressure of 0.01 Torr. The field emission response, i.e., the turn-on field (2.5 V/μm) and the maximum emission current density (2.17 mA/cm2) of the CNTs synthesized at the temperature of 550 °C and pressure of 1 atm (760 Torr) was found to be excellent.
{"title":"Systematic growth of carbon nanotubes on aluminum substrate for enhanced field emission performance","authors":"P. Maity, S. Gandhi, Manuj Dixit, I. Lahiri","doi":"10.1116/6.0000560","DOIUrl":"https://doi.org/10.1116/6.0000560","url":null,"abstract":"For more than two decades, carbon nanotubes (CNTs) have shown great potential for a wide range of applications. Several methods are known to synthesize CNTs, though only a few of them are able to produce good quality and economically available CNTs. Chemical vapor deposition (CVD) is one of those methods that produce economically feasible and good quality CNTs onto specific substrates, even with nanopatterning. However, growing CNTs by CVD at temperatures below 700 °C remained a long-time challenge, as this meant keeping a host of low-melting materials out of bounds for direct CNT growth on them. In this work, CNTs have been synthesized directly onto a low-melting, conducting substrate, aluminum, by thermal CVD, at a temperature as low as 550 °C and up to as high as 650 °C (just below the melting point of aluminum). The diameters of the grown CNTs were observed to be influenced by process parameters, e.g., temperature and pressure. The effect of synthesis parameters on CNT diameters was verified by scanning electron microscopy and transmission electron microscopy. The quality of the CNTs was checked by Raman spectroscopy, selected area electron diffraction pattern of transmission electron microscopy, and XPS. It was observed that an increase in temperature and pressure had a significant effect on the diameters of the CNTs. Randomly entangled CNTs were measured to have an average diameter of 28 nm at 550 °C and one atmospheric (760 Torr) pressure, whereas it was observed to be 78 nm at a temperature of 650 °C and pressure of 0.01 Torr. The field emission response, i.e., the turn-on field (2.5 V/μm) and the maximum emission current density (2.17 mA/cm2) of the CNTs synthesized at the temperature of 550 °C and pressure of 1 atm (760 Torr) was found to be excellent.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88284815","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}
N. Ryskin, Roman A. Torgashov, A. Starodubov, A. Rozhnev, A. Serdobintsev, A. Pavlov, V. Galushka, D. Bessonov, G. Ulisse, V. Krozer
We report the results of the design, simulation, fabrication, and cold-test measurements of millimeter-band 2D planar microstrip slow-wave structures (SWSs) on dielectric substrates. Such structures have a high slow-wave factor, which allows for low-voltage operation and reduction in the size and weight of the device. A low-cost and flexible fabrication technology based on magnetron sputtering and subsequent laser ablation has been developed and is reported in the paper. Microstrip meander-line SWS circuits at V-, W-, and D-bands have been fabricated and characterized. The fabrication of ring-bar planar SWSs by the photolithographic method is also discussed. Experimental measurement of S-parameters of the fabricated structures reveals good transmission properties. Return loss (S11) does not exceed −10 dB and attenuation is about 2 dB/cm in the V-band, 10 dB/cm in the W-band, and 8.5 dB/cm in the D-band.
{"title":"Development of microfabricated planar slow-wave structures on dielectric substrates for miniaturized millimeter-band traveling-wave tubes","authors":"N. Ryskin, Roman A. Torgashov, A. Starodubov, A. Rozhnev, A. Serdobintsev, A. Pavlov, V. Galushka, D. Bessonov, G. Ulisse, V. Krozer","doi":"10.1116/6.0000716","DOIUrl":"https://doi.org/10.1116/6.0000716","url":null,"abstract":"We report the results of the design, simulation, fabrication, and cold-test measurements of millimeter-band 2D planar microstrip slow-wave structures (SWSs) on dielectric substrates. Such structures have a high slow-wave factor, which allows for low-voltage operation and reduction in the size and weight of the device. A low-cost and flexible fabrication technology based on magnetron sputtering and subsequent laser ablation has been developed and is reported in the paper. Microstrip meander-line SWS circuits at V-, W-, and D-bands have been fabricated and characterized. The fabrication of ring-bar planar SWSs by the photolithographic method is also discussed. Experimental measurement of S-parameters of the fabricated structures reveals good transmission properties. Return loss (S11) does not exceed −10 dB and attenuation is about 2 dB/cm in the V-band, 10 dB/cm in the W-band, and 8.5 dB/cm in the D-band.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85793769","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}
Hamed Alemansour, S. Moheimani, J. Owen, J. Randall, E. Fuchs
The scanning tunneling microscope (STM) has enabled manipulation and interrogation of surfaces with atomic-scale resolution. Electronic information about a surface is obtained by combining the imaging capability of the STM with scanning tunneling spectroscopy, i.e., measurement of current-voltage (I/V) characteristics of the surface. We propose a change in the STM feedback loop that enables capturing a higher quality dI/dV image. A high frequency dither voltage is added to the bias voltage of the sample, and the fundamental frequency component of the resulting current is demodulated. The in-phase component of this signal is then plotted along with the X and Y position data, constructing the dI/dV image. We show that by incorporating notch filters in the STM feedback loop, we may utilize a high-amplitude dither voltage to significantly improve the quality of the obtained dI/dV image.
{"title":"High signal-to-noise ratio differential conductance spectroscopy","authors":"Hamed Alemansour, S. Moheimani, J. Owen, J. Randall, E. Fuchs","doi":"10.1116/6.0000823","DOIUrl":"https://doi.org/10.1116/6.0000823","url":null,"abstract":"The scanning tunneling microscope (STM) has enabled manipulation and interrogation of surfaces with atomic-scale resolution. Electronic information about a surface is obtained by combining the imaging capability of the STM with scanning tunneling spectroscopy, i.e., measurement of current-voltage (I/V) characteristics of the surface. We propose a change in the STM feedback loop that enables capturing a higher quality dI/dV image. A high frequency dither voltage is added to the bias voltage of the sample, and the fundamental frequency component of the resulting current is demodulated. The in-phase component of this signal is then plotted along with the X and Y position data, constructing the dI/dV image. We show that by incorporating notch filters in the STM feedback loop, we may utilize a high-amplitude dither voltage to significantly improve the quality of the obtained dI/dV image.","PeriodicalId":17652,"journal":{"name":"Journal of Vacuum Science & Technology. B. Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phenomena","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2021-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89739246","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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