Breast cancer is considered a leading health problem, especially in women, and is a major contributor to the annual worldwide cancer mortality rate. Various drawbacks and a range of side effects are faced by cancer patients undergoing the conventional cancer therapy methods that do not always result in positive and successful outcomes. Current research introducing nanomaterials into in vivo breast cancer therapy applications has revolutionized various aspects of these therapies. These include conjugating natural compounds onto nanoparticles (NPs) such as curcumin that exhibit chemopreventive activity, and controlled drug release targeting specific organs or tumor sites, thereby reducing the side effects otherwise caused by conventional cancer therapy. Recently, folate-tagged gold nanoparticles (AuNPs) are proving to be the leading nanocarriers used in cancer treatment and detection and can also be combined with different therapies such as chemotherapy, radiotherapy, and photothermal therapy. The development of such nano-based systems possessing enzyme mimetic properties, blood compatibility, and the ability to differentiate between normal cells and cancer cell properties deems them suitable for in vivo applications and have attracted enormous attention for devising early detection and diagnosis for breast cancer. In this review, we will discuss recent progress in the use of curcumin as a chemopreventive drug in cancer therapy and review the different routes in use for the synthesis and functionalization of Au NPs. Finally, we will review the current state of research with respect to curcumin and folic acid-conjugated Au NPs and their applications in detection, diagnosis, and treatment of breast cancer.
{"title":"Folated curcumin-gold nanoformulations: A nanotherapeutic strategy for breast cancer therapy","authors":"Sneha Mahalunkar, G. Kundu, S. Gosavi","doi":"10.1116/6.0000148","DOIUrl":"https://doi.org/10.1116/6.0000148","url":null,"abstract":"Breast cancer is considered a leading health problem, especially in women, and is a major contributor to the annual worldwide cancer mortality rate. Various drawbacks and a range of side effects are faced by cancer patients undergoing the conventional cancer therapy methods that do not always result in positive and successful outcomes. Current research introducing nanomaterials into in vivo breast cancer therapy applications has revolutionized various aspects of these therapies. These include conjugating natural compounds onto nanoparticles (NPs) such as curcumin that exhibit chemopreventive activity, and controlled drug release targeting specific organs or tumor sites, thereby reducing the side effects otherwise caused by conventional cancer therapy. Recently, folate-tagged gold nanoparticles (AuNPs) are proving to be the leading nanocarriers used in cancer treatment and detection and can also be combined with different therapies such as chemotherapy, radiotherapy, and photothermal therapy. The development of such nano-based systems possessing enzyme mimetic properties, blood compatibility, and the ability to differentiate between normal cells and cancer cell properties deems them suitable for in vivo applications and have attracted enormous attention for devising early detection and diagnosis for breast cancer. In this review, we will discuss recent progress in the use of curcumin as a chemopreventive drug in cancer therapy and review the different routes in use for the synthesis and functionalization of Au NPs. Finally, we will review the current state of research with respect to curcumin and folic acid-conjugated Au NPs and their applications in detection, diagnosis, and treatment of breast cancer.","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":"2020-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78686221","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}
Laser-cooled gases offer an alternative to tip-based methods for generating high-brightness ion beams for focused ion beam applications. These sources produce ions by photoionization of ultracold neutral atoms, where the narrow velocity distribution associated with microkelvin-level temperatures results in a very low emittance, high-brightness ion beam. In a magneto-optical trap-based ion source, the brightness is ultimately limited by the transport of cold neutral atoms, which restricts the current that can be extracted from the ion-generating volume. We explore the dynamics of this transport in a 7Li magneto-optical trap ion source by performing time-dependent measurements of the depletion and refilling of the ionization volume in a pulsed source. An analytic microscopic model for the transport is developed, and this model shows excellent agreement with the measured results.
{"title":"Transport dynamics in a high-brightness magneto-optical-trap Li ion source","authors":"J. Gardner, W. McGehee, M. Stiles, J. McClelland","doi":"10.1116/6.0000394","DOIUrl":"https://doi.org/10.1116/6.0000394","url":null,"abstract":"Laser-cooled gases offer an alternative to tip-based methods for generating high-brightness ion beams for focused ion beam applications. These sources produce ions by photoionization of ultracold neutral atoms, where the narrow velocity distribution associated with microkelvin-level temperatures results in a very low emittance, high-brightness ion beam. In a magneto-optical trap-based ion source, the brightness is ultimately limited by the transport of cold neutral atoms, which restricts the current that can be extracted from the ion-generating volume. We explore the dynamics of this transport in a 7Li magneto-optical trap ion source by performing time-dependent measurements of the depletion and refilling of the ionization volume in a pulsed source. An analytic microscopic model for the transport is developed, and this model shows excellent agreement with the measured results.","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":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74830824","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}
M. Miyoshi, Taiki Nakabayashi, M. Yamanaka, T. Egawa, T. Takeuchi
In this study, Si-doped conductive AlInN films with a thickness of 300 nm were grown nearly lattice-matched to c-plane GaN-on-sapphire templates by metalorganic chemical vapor deposition. A high net donor concentration of approximately 1 × 1019 cm−3 was observed for a highly Si-doped AlInN film. To evaluate its vertical-direction electrical resistivity without being affected by polarization-induced carriers, the transfer length measurement (TLM) model was applied to two kinds of test element groups. By analyzing the TLM results, the vertical-direction resistivity of the 300-nm-thick n-type AlInN film was estimated to be 5.8 × 10−4 Ω cm2.
{"title":"Electrical characterization of Si-doped conductive AlInN films grown nearly lattice-matched to c-plane GaN on sapphire by metalorganic chemical vapor deposition","authors":"M. Miyoshi, Taiki Nakabayashi, M. Yamanaka, T. Egawa, T. Takeuchi","doi":"10.1116/6.0000284","DOIUrl":"https://doi.org/10.1116/6.0000284","url":null,"abstract":"In this study, Si-doped conductive AlInN films with a thickness of 300 nm were grown nearly lattice-matched to c-plane GaN-on-sapphire templates by metalorganic chemical vapor deposition. A high net donor concentration of approximately 1 × 1019 cm−3 was observed for a highly Si-doped AlInN film. To evaluate its vertical-direction electrical resistivity without being affected by polarization-induced carriers, the transfer length measurement (TLM) model was applied to two kinds of test element groups. By analyzing the TLM results, the vertical-direction resistivity of the 300-nm-thick n-type AlInN film was estimated to be 5.8 × 10−4 Ω cm2.","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":"2020-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88303358","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}
Catlin N. Schalk, David A. Turner, Ashley R. Gans-Forrest, Matthew M. Jobbins, S. Kandel
A mechanism is described for the loading and unloading of samples from an instrument housing in a way that achieves strong mechanical contact between the sample and housing. A single linear–rotary magnetically coupled feedthrough is required to effect transfer. An additional load-lock mechanism requires only a single linear magnetic feedthrough, which remains in the UHV part of the chamber. The load-lock itself has no motion feedthroughs, which simplifies design and maximizes the pump-down speed. 3D-printing technology allows for intricately detailed parts to be used in both the sample transfer and load-lock mechanisms.
{"title":"Simple, low degree-of-freedom load-lock and in-vacuum sample transfer","authors":"Catlin N. Schalk, David A. Turner, Ashley R. Gans-Forrest, Matthew M. Jobbins, S. Kandel","doi":"10.1116/6.0000495","DOIUrl":"https://doi.org/10.1116/6.0000495","url":null,"abstract":"A mechanism is described for the loading and unloading of samples from an instrument housing in a way that achieves strong mechanical contact between the sample and housing. A single linear–rotary magnetically coupled feedthrough is required to effect transfer. An additional load-lock mechanism requires only a single linear magnetic feedthrough, which remains in the UHV part of the chamber. The load-lock itself has no motion feedthroughs, which simplifies design and maximizes the pump-down speed. 3D-printing technology allows for intricately detailed parts to be used in both the sample transfer and load-lock mechanisms.","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":"2020-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72688028","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}
Rectangular-shaped oxygen O2+ ion beam thinning for scanning transmission electron microscope (STEM) sample preparation was investigated using a projection ion beam optical system equipped with a duoplasmatron gas ion source. The ion current can be increased by increasing the area of the rectangular-shaped oxygen ion beam and thereby overcome the low brightness of the ion source. Rectangular-shaped O2+ ion beams with different amounts of projection beam edge blur were formed in the X and Y directions by using a limiting mask between the ion source and projection mask. Gallium-contamination-free STEM sample preparation (rough, medium, and fine milling) was demonstrated using a projection ion beam optical system and three types of rectangular-shaped oxygen ion beams.
{"title":"Ga-contamination-free scanning transmission electron microscope sample preparation by rectangular-shaped oxygen-ion-beam thinning using projection ion beam optical system","authors":"H. Shichi, S. Tomimatsu","doi":"10.1116/6.0000297","DOIUrl":"https://doi.org/10.1116/6.0000297","url":null,"abstract":"Rectangular-shaped oxygen O2+ ion beam thinning for scanning transmission electron microscope (STEM) sample preparation was investigated using a projection ion beam optical system equipped with a duoplasmatron gas ion source. The ion current can be increased by increasing the area of the rectangular-shaped oxygen ion beam and thereby overcome the low brightness of the ion source. Rectangular-shaped O2+ ion beams with different amounts of projection beam edge blur were formed in the X and Y directions by using a limiting mask between the ion source and projection mask. Gallium-contamination-free STEM sample preparation (rough, medium, and fine milling) was demonstrated using a projection ion beam optical system and three types of rectangular-shaped oxygen ion beams.","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":"2020-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87067409","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}
Organic light-emitting diodes are important in display applications, but thin films used in these devices often exhibit complex and highly disordered structures. We have studied the adsorption of a typical hole transport material used in such devices, N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD), on the Au(111) surface. Scanning tunneling microscopy images reveal the appearance of different conformations in the first monolayer with submolecular resolution. Scanning tunneling spectra identify the highest occupied molecular orbital on several different adsorption structures. We directly compare the statistical distribution of this orbital energy between an ordered monolayer structure and a disordered bilayer structure of α-NPD on Au(111). The disordered structure exhibits a very broad distribution that is consistent with inferences from prior organic device studies and that we propose arises from minor conformational variations.
{"title":"Direct molecular quantification of electronic disorder in N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine on Au(111)","authors":"Jiuyang Wang, Jingying Wang, D. Dougherty","doi":"10.1116/6.0000401","DOIUrl":"https://doi.org/10.1116/6.0000401","url":null,"abstract":"Organic light-emitting diodes are important in display applications, but thin films used in these devices often exhibit complex and highly disordered structures. We have studied the adsorption of a typical hole transport material used in such devices, N,N′-Di-[(1-naphthyl)-N,N′-diphenyl]-1,1′-biphenyl)-4,4′-diamine (α-NPD), on the Au(111) surface. Scanning tunneling microscopy images reveal the appearance of different conformations in the first monolayer with submolecular resolution. Scanning tunneling spectra identify the highest occupied molecular orbital on several different adsorption structures. We directly compare the statistical distribution of this orbital energy between an ordered monolayer structure and a disordered bilayer structure of α-NPD on Au(111). The disordered structure exhibits a very broad distribution that is consistent with inferences from prior organic device studies and that we propose arises from minor conformational variations.","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":"2020-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86625965","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 spin-based memory, spin transfer torque-magnetic random access memory (STT-MRAM), has the potential to enhance the power efficiency of high density memory systems. Its desirable characteristics include nonvolatility, fast operation, and long endurance. However, dry etching of MRAM structures remains a challenge as the industry is ramping up its production. In this paper, we explore the etching strategies that have been used to etch the MRAM structures. Several etching techniques have been developed to attain optimal device performance. These are reactive ion etching, time modulated plasma etching, atomic layer etching, and ion beam etching. Sidewall profile, sidewall contamination or damage, redeposition, selectivity, and noncorrosiveness are the main factors to consider while selecting the best etching methods. This paper starts with the fundamentals of MRAM reading, writing, and storing principles and finishes with the current approaches to solve the etch challenges. For etching, the most commonly used magnetic materials such as CoFeB, CoFe, and NiFe are covered in this article.
{"title":"Dry etching strategy of spin-transfer-torque magnetic random access memory: A review","authors":"R. Islam, B. Cui, G. Miao","doi":"10.1116/6.0000205","DOIUrl":"https://doi.org/10.1116/6.0000205","url":null,"abstract":"The spin-based memory, spin transfer torque-magnetic random access memory (STT-MRAM), has the potential to enhance the power efficiency of high density memory systems. Its desirable characteristics include nonvolatility, fast operation, and long endurance. However, dry etching of MRAM structures remains a challenge as the industry is ramping up its production. In this paper, we explore the etching strategies that have been used to etch the MRAM structures. Several etching techniques have been developed to attain optimal device performance. These are reactive ion etching, time modulated plasma etching, atomic layer etching, and ion beam etching. Sidewall profile, sidewall contamination or damage, redeposition, selectivity, and noncorrosiveness are the main factors to consider while selecting the best etching methods. This paper starts with the fundamentals of MRAM reading, writing, and storing principles and finishes with the current approaches to solve the etch challenges. For etching, the most commonly used magnetic materials such as CoFeB, CoFe, and NiFe are covered in this article.","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":"2020-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89355021","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}
J. Ludwick, A. Iqbal, D. Gortat, J. D. Cook, M. Cahay, Peng Zhang, T. Back, S. Fairchild, M. Sparkes, W. O'Neill
We report exhaustive measurements of the secondary electron yield (SEY) from a gold film containing an array of micropores as a function of the angle of incidence of the primary electrons. The SEY measurements are in good agreement with Monte-Carlo (MC) simulations. A highly accurate empirical fit to the SEY data as a function of the incident electron impact angle is also proposed. In this study, the micropores have aspect ratios (ratio of pore height over pore diameter) ranging from about 1.5 to 3.5. The effect of the pore array density (porosity) and pore aspect ratio is analyzed in greater detail. It is found that increasing the pore aspect ratio and porosity leads to a sharp reduction in the total SEY in agreement with MC simulations.
{"title":"Angular dependence of secondary electron yield from microporous gold surfaces","authors":"J. Ludwick, A. Iqbal, D. Gortat, J. D. Cook, M. Cahay, Peng Zhang, T. Back, S. Fairchild, M. Sparkes, W. O'Neill","doi":"10.1116/6.0000346","DOIUrl":"https://doi.org/10.1116/6.0000346","url":null,"abstract":"We report exhaustive measurements of the secondary electron yield (SEY) from a gold film containing an array of micropores as a function of the angle of incidence of the primary electrons. The SEY measurements are in good agreement with Monte-Carlo (MC) simulations. A highly accurate empirical fit to the SEY data as a function of the incident electron impact angle is also proposed. In this study, the micropores have aspect ratios (ratio of pore height over pore diameter) ranging from about 1.5 to 3.5. The effect of the pore array density (porosity) and pore aspect ratio is analyzed in greater detail. It is found that increasing the pore aspect ratio and porosity leads to a sharp reduction in the total SEY in agreement with MC simulations.","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":"2020-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87140814","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}
S. Sasaki, K. Dropiewski, S. Madisetti, V. Tokranov, M. Yakimov, S. Oktyabrsky
p-type GaSb metal–oxide–semiconductor capacitors with thin InAs surface capping layers were prepared on Si(001) substrates. Epitaxial structures with superlattice metamorphic buffer layers were grown by molecular beam epitaxy. Chemical surface treatment and atomic layer deposition methods were employed for a semiconductor surface passivation and Al2O3 high-k oxide fabrication, respectively. Capacitance-voltage measurements and scanning and transmission electron microscopies were used to correlate electrical properties with the oxide-semiconductor interface structure of the capacitors. Unexpectedly, fast minority carrier response present down to liquid nitrogen temperature was observed in the capacitors passivated by an ammonium sulfide solution. This fast response was found to be related to etch pitlike surface morphology developed upon chemical passivation at the surface steps formed by microtwins and antiphase domain boundaries. Preferential InAs etching by ammonium sulfide at the surface defects was confirmed by analytical TEM studies. Very low activation energy of minority carrier response suggests the presence of electron sources under the gate; they result from growth-related surface defects that give rise to potential fluctuations of as high as half the GaSb bandgap.
{"title":"Anomalous minority carrier behavior induced by chemical surface passivation solution in p-type GaSb metal–oxide–semiconductor capacitors on Si substrates","authors":"S. Sasaki, K. Dropiewski, S. Madisetti, V. Tokranov, M. Yakimov, S. Oktyabrsky","doi":"10.1116/6.0000169","DOIUrl":"https://doi.org/10.1116/6.0000169","url":null,"abstract":"p-type GaSb metal–oxide–semiconductor capacitors with thin InAs surface capping layers were prepared on Si(001) substrates. Epitaxial structures with superlattice metamorphic buffer layers were grown by molecular beam epitaxy. Chemical surface treatment and atomic layer deposition methods were employed for a semiconductor surface passivation and Al2O3 high-k oxide fabrication, respectively. Capacitance-voltage measurements and scanning and transmission electron microscopies were used to correlate electrical properties with the oxide-semiconductor interface structure of the capacitors. Unexpectedly, fast minority carrier response present down to liquid nitrogen temperature was observed in the capacitors passivated by an ammonium sulfide solution. This fast response was found to be related to etch pitlike surface morphology developed upon chemical passivation at the surface steps formed by microtwins and antiphase domain boundaries. Preferential InAs etching by ammonium sulfide at the surface defects was confirmed by analytical TEM studies. Very low activation energy of minority carrier response suggests the presence of electron sources under the gate; they result from growth-related surface defects that give rise to potential fluctuations of as high as half the GaSb bandgap.","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":"2020-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90501782","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}
M. A. Haque, N. Lavrik, A. Hedayatipour, D. Hensley, Dayrl P. Briggs, N. Mcfarlane
Carbon based electrodes suitable for integration with CMOS readout electronics are of great importance for a variety of emerging applications. In this study, we have looked into the prerequisites for the optimized pyrolytic conversion of 3D printed polymer microstructures and nanostructures with the goal of developing sensing electrodes for a lab-on-CMOS electrochemical system. As a result, we identified conditions for a sequence of anneals in oxidative and inert environments that yield carbonized structures on metallized substrates with improved shape retention, while also providing electrical insulation of the surrounding metal stack. We demonstrated that titanium metal layers can be conveniently used to form electrically insulating titanium oxide on the substrate outside the carbonized structures in a self-aligned fashion. However, significant shrinkage of polymer structures formed by 3D printing or stereolithography is inevitable during their pyrolysis. Furthermore, the catalytically active titanium oxide present during initial stages of carbonization leads to additional loss of carbon and significant artifacts in the resulting structures. To minimize these adverse effects of titanium oxide on the shape retention of the carbonized structures, we developed an optimized processing sequence. Various processing steps in this sequence were characterized in terms of their effects on titanium oxide growth and geometrical changes in the 3D printed structures, while impedance and Raman spectroscopy were performed to evaluate their degree of pyrolytic conversion and, therefore, potential for electrochemical sensing.
{"title":"Carbonization of 3D printed polymer structures for CMOS-compatible electrochemical sensors","authors":"M. A. Haque, N. Lavrik, A. Hedayatipour, D. Hensley, Dayrl P. Briggs, N. Mcfarlane","doi":"10.1116/6.0000266","DOIUrl":"https://doi.org/10.1116/6.0000266","url":null,"abstract":"Carbon based electrodes suitable for integration with CMOS readout electronics are of great importance for a variety of emerging applications. In this study, we have looked into the prerequisites for the optimized pyrolytic conversion of 3D printed polymer microstructures and nanostructures with the goal of developing sensing electrodes for a lab-on-CMOS electrochemical system. As a result, we identified conditions for a sequence of anneals in oxidative and inert environments that yield carbonized structures on metallized substrates with improved shape retention, while also providing electrical insulation of the surrounding metal stack. We demonstrated that titanium metal layers can be conveniently used to form electrically insulating titanium oxide on the substrate outside the carbonized structures in a self-aligned fashion. However, significant shrinkage of polymer structures formed by 3D printing or stereolithography is inevitable during their pyrolysis. Furthermore, the catalytically active titanium oxide present during initial stages of carbonization leads to additional loss of carbon and significant artifacts in the resulting structures. To minimize these adverse effects of titanium oxide on the shape retention of the carbonized structures, we developed an optimized processing sequence. Various processing steps in this sequence were characterized in terms of their effects on titanium oxide growth and geometrical changes in the 3D printed structures, while impedance and Raman spectroscopy were performed to evaluate their degree of pyrolytic conversion and, therefore, potential for electrochemical sensing.","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":"2020-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78126433","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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