Pub Date : 2017-04-21DOI: 10.1109/WMED.2017.7916923
Chen Zhu, P. Andrei
In this presentation we introduce a robust technique for the design and optimization of the on-state resistance and breakdown voltages in power transistors, including high-electron mobility transistors (HEMTs), metal-oxide-semiconductor (MOS) power devices, insolated-gate bipolar transistors (IGBTs), and power rectifying diodes. The technique is based on the formalism of doping sensitivity functions and allows the computation of the optimum doping profile that maximizes the breakdown voltage and minimizes the on-state resistance of the above devices. Sample numerical simulation results will be presented for a AlGaN/GaN HEMT.
{"title":"Adjoint Method to Optimize Power Transistors","authors":"Chen Zhu, P. Andrei","doi":"10.1109/WMED.2017.7916923","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916923","url":null,"abstract":"In this presentation we introduce a robust technique for the design and optimization of the on-state resistance and breakdown voltages in power transistors, including high-electron mobility transistors (HEMTs), metal-oxide-semiconductor (MOS) power devices, insolated-gate bipolar transistors (IGBTs), and power rectifying diodes. The technique is based on the formalism of doping sensitivity functions and allows the computation of the optimum doping profile that maximizes the breakdown voltage and minimizes the on-state resistance of the above devices. Sample numerical simulation results will be presented for a AlGaN/GaN HEMT.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117010421","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}
Pub Date : 2017-04-21DOI: 10.1109/WMED.2017.7916930
Richard L. Chaney, Dale G. Wilson, D. Hackler, K. DeGregorio, Darrell E. Leber
Flexible Hybrid Electronics combine the best characteristics of printed electronics and silicon ICs to create high performance, ultra-thin, physically flexible systems. Advances in converting commercial off-the-shelf products into the physically flexible FleX-IC format are presented. This paper examines the FleX-SoC, physically flexible System-on-Chip, and reports evaluation of the NVM after bending with a radius of curvature down to 5mm.
{"title":"New Silicon Frontiers: Physically Flexible System-On-A-Chip","authors":"Richard L. Chaney, Dale G. Wilson, D. Hackler, K. DeGregorio, Darrell E. Leber","doi":"10.1109/WMED.2017.7916930","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916930","url":null,"abstract":"Flexible Hybrid Electronics combine the best characteristics of printed electronics and silicon ICs to create high performance, ultra-thin, physically flexible systems. Advances in converting commercial off-the-shelf products into the physically flexible FleX-IC format are presented. This paper examines the FleX-SoC, physically flexible System-on-Chip, and reports evaluation of the NVM after bending with a radius of curvature down to 5mm.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132324455","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}
Pub Date : 2017-04-21DOI: 10.1109/WMED.2017.7916927
Sumedha Gandharava, Catherine N. Walker, K. D. Cantley
Resistive memory devices have been studied and fabricated using a wide variety of materials including chalcogenides, metal oxides, and hydrogenated amorphous silicon (a-Si:H). The most promising materials seem to be amorphous in nature, with the properties of the atomic lattices being conducive to the physical mechanisms that underlie the subsequent resistive switching. The devices are also finding applications beyond high-density digital memory, such as for electronic synapses in neuromorphic systems. However, a different set of properties is required in the latter case compared to devices that must only store binary values. In addition, it is well known that biological synapses are extremely unreliable and noisy, and yet the brain is still able to perform high-level cognitive functions. This work uses pulse-based electrical characterization techniques to demonstrate the stochastic nature of resistive switching in nanocrystalline silicon (nc-Si) Conductive Bridge Resistive Memory (CBRAM) Devices. We chose nc-Si active layers so these devices could potentially be co-fabricated in the same process as nc-Si TFTs. Our subsequent findings indicate the device properties may be particularly useful for some non-von Neumann computing paradigms. Though much research has been done using a-Si:H, results from nc-Si CBRAM devices have not been published. In this study, we showed that the switching of the device depends on the history of current passing though it, and not only the voltage applied. Further, the resistance switching in the devices is stochastic, making them ideal candidates for a biologically realistic synapse.
{"title":"Electrical characteristics of nanocrystalline silicon resistive memory devices","authors":"Sumedha Gandharava, Catherine N. Walker, K. D. Cantley","doi":"10.1109/WMED.2017.7916927","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916927","url":null,"abstract":"Resistive memory devices have been studied and fabricated using a wide variety of materials including chalcogenides, metal oxides, and hydrogenated amorphous silicon (a-Si:H). The most promising materials seem to be amorphous in nature, with the properties of the atomic lattices being conducive to the physical mechanisms that underlie the subsequent resistive switching. The devices are also finding applications beyond high-density digital memory, such as for electronic synapses in neuromorphic systems. However, a different set of properties is required in the latter case compared to devices that must only store binary values. In addition, it is well known that biological synapses are extremely unreliable and noisy, and yet the brain is still able to perform high-level cognitive functions. This work uses pulse-based electrical characterization techniques to demonstrate the stochastic nature of resistive switching in nanocrystalline silicon (nc-Si) Conductive Bridge Resistive Memory (CBRAM) Devices. We chose nc-Si active layers so these devices could potentially be co-fabricated in the same process as nc-Si TFTs. Our subsequent findings indicate the device properties may be particularly useful for some non-von Neumann computing paradigms. Though much research has been done using a-Si:H, results from nc-Si CBRAM devices have not been published. In this study, we showed that the switching of the device depends on the history of current passing though it, and not only the voltage applied. Further, the resistance switching in the devices is stochastic, making them ideal candidates for a biologically realistic synapse.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133070090","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}
Pub Date : 2017-04-21DOI: 10.1109/WMED.2017.7916921
Yuan Chen, Lei Zhang, Yan Wang
This paper presents a 150GHz fully differential amplifier with gain boosting and optimized Marchand balun matching networks in a 65nm CMOS technology. The optimized Marchand balun overcomes the self- resonance problem that the conventional balun suffers, and reduces the size as well. The over- neutralization technique is proposed and utilized in order to boost the gain of a differential pair without extra penalty on power consumption. A four- stage amplifier achieves a maximum gain of 19.2dB at 150GHz with a 3dB bandwidth of 14GHz, while consuming 48mW of power from a 1.2V supply.
{"title":"A 150Ghz High Gain Amplifier Based on over Neutralization Technique and Marchand Balun Matching Networks in 65nm CMOS","authors":"Yuan Chen, Lei Zhang, Yan Wang","doi":"10.1109/WMED.2017.7916921","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916921","url":null,"abstract":"This paper presents a 150GHz fully differential amplifier with gain boosting and optimized Marchand balun matching networks in a 65nm CMOS technology. The optimized Marchand balun overcomes the self- resonance problem that the conventional balun suffers, and reduces the size as well. The over- neutralization technique is proposed and utilized in order to boost the gain of a differential pair without extra penalty on power consumption. A four- stage amplifier achieves a maximum gain of 19.2dB at 150GHz with a 3dB bandwidth of 14GHz, while consuming 48mW of power from a 1.2V supply.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124231205","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}
Pub Date : 2017-04-21DOI: 10.1109/WMED.2017.7916926
Greg Spencer, M. Hagmann
Summary form only given. We are developing a scanning tunneling microscope that is portable and optimized for scanning frequency comb microscopy (SFCM) as one part of our effort to complete a prototype for the carrier profiling of semiconductors by SFCM. Conventional integral or integral plus proportion feedback control of the tunneling current in a scanning tunneling microscope (STM) is satisfactory once tunneling has been established but may cause tip-crash by integral windup during coarse approach. In tip-sample contact images with atomic-resolution may be obtained but the microwave frequency comb ceases because there is no optical rectification and scanning tunneling spectroscopy also fails. We are studying a new control algorithm based on approximating the tunneling current as a polynomial in the bias voltage where the coefficients in this polynomial are not required. It is noted that hanges in the apparatus, as well as the algorithms used for feedback control in the STM, are required to optimize this instrument for measuring the microwave frequency comb.
{"title":"Development of a scanning tunneling microscope for the carrier profiling of semiconductors by scanning frequency comb microscopy","authors":"Greg Spencer, M. Hagmann","doi":"10.1109/WMED.2017.7916926","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916926","url":null,"abstract":"Summary form only given. We are developing a scanning tunneling microscope that is portable and optimized for scanning frequency comb microscopy (SFCM) as one part of our effort to complete a prototype for the carrier profiling of semiconductors by SFCM. Conventional integral or integral plus proportion feedback control of the tunneling current in a scanning tunneling microscope (STM) is satisfactory once tunneling has been established but may cause tip-crash by integral windup during coarse approach. In tip-sample contact images with atomic-resolution may be obtained but the microwave frequency comb ceases because there is no optical rectification and scanning tunneling spectroscopy also fails. We are studying a new control algorithm based on approximating the tunneling current as a polynomial in the bias voltage where the coefficients in this polynomial are not required. It is noted that hanges in the apparatus, as well as the algorithms used for feedback control in the STM, are required to optimize this instrument for measuring the microwave frequency comb.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126740804","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}
Pub Date : 2017-04-01DOI: 10.1109/WMED.2017.7916922
Kelsey Suyehira, Simon Llewellyn, Reza M Zadegan, W. Hughes, Tim Andersen
The global demand for digital data is projected to be greater than the supply of semiconductor grade silicon in 2040 [1]. When combined with the need to archive information [2], nucleic acids are being explored as an alternative memory material [1-7]. According to a recent study, the information density of nucleic acid memory (NAM) is one thousand times greater than flash memory and has the ability to last for hundreds of years [1]. Presented here is an algorithm for converting digital data into unique DNA sequences for glacial storage. Biologically inspired, our coding scheme maps hexadecimal characters to sequences of three DNA nucleotides. This mapping avoids repeating sequences and start codons, which could have adverse effects. We were able to encode and decode various file types without error.
{"title":"A Coding Scheme for Nucleic Acid Memory (NAM)","authors":"Kelsey Suyehira, Simon Llewellyn, Reza M Zadegan, W. Hughes, Tim Andersen","doi":"10.1109/WMED.2017.7916922","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916922","url":null,"abstract":"The global demand for digital data is projected to be greater than the supply of semiconductor grade silicon in 2040 [1]. When combined with the need to archive information [2], nucleic acids are being explored as an alternative memory material [1-7]. According to a recent study, the information density of nucleic acid memory (NAM) is one thousand times greater than flash memory and has the ability to last for hundreds of years [1]. Presented here is an algorithm for converting digital data into unique DNA sequences for glacial storage. Biologically inspired, our coding scheme maps hexadecimal characters to sequences of three DNA nucleotides. This mapping avoids repeating sequences and start codons, which could have adverse effects. We were able to encode and decode various file types without error.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114026424","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}
Pub Date : 2017-04-01DOI: 10.1109/WMED.2017.7916934
Chen Zhu, P. Andrei, M. Hagmann
In this article we use the ensemble Monte-Carlo method to study the frequency comb induced by a periodically excited tunnel junction on a semiconductor. The electron transport is modeled by solving the Boltzmann transport in p-type silicon doped with a concentration of 10^17 cm^-3. For a laser-pulse frequency of 100 MHz, we observe that, if the distance between the STM probe and the second electrode is under 1 μm and we apply a negative bias on the STM tip, the harmonics of the frequency spectrum are not reduced significantly by the electron diffusion and resistance spreading effects in the semiconductor. In this case we obtain a wide frequency comb spectrum, relatively similar to the ones measured experimentally in metals and other materials with high electron conductivity.
{"title":"Simulation of the Frequency Comb Induced by a Periodically Excited Tunnel Junction in Silicon","authors":"Chen Zhu, P. Andrei, M. Hagmann","doi":"10.1109/WMED.2017.7916934","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916934","url":null,"abstract":"In this article we use the ensemble Monte-Carlo method to study the frequency comb induced by a periodically excited tunnel junction on a semiconductor. The electron transport is modeled by solving the Boltzmann transport in p-type silicon doped with a concentration of 10^17 cm^-3. For a laser-pulse frequency of 100 MHz, we observe that, if the distance between the STM probe and the second electrode is under 1 μm and we apply a negative bias on the STM tip, the harmonics of the frequency spectrum are not reduced significantly by the electron diffusion and resistance spreading effects in the semiconductor. In this case we obtain a wide frequency comb spectrum, relatively similar to the ones measured experimentally in metals and other materials with high electron conductivity.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125234658","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}
Pub Date : 2017-04-01DOI: 10.1109/WMED.2017.7916932
Brandon Hardie, M. Roll
Extreme Ultra-violet Lithography (EUVL), regardless of some setbacks, has continued its push as a viable option for next generation nodes of photolithography. Utilizing a 13.5nm wavelength, EUV is still showing promise as a natural progression of optical lithography in the semiconductor industry. Despite this upside, EUVL also has its drawbacks, one of which includes the development of a suitable photoresist material. The development and characterization of polyoxometalate (POM) hybrid nano-building blocks (NBBs) shows great potential as a candidate for improving the patterning of semiconductor devices using EUVL. Octamolybdate macromolecules were synthesized using literature methods. These primary materials were modified for improvements using a combination of physical mixtures with photoacids (resist sensitivity) and epoxide (mechanical stability). In addition, tellurium atoms (EUV absorption) were incorporated chemically and will be explored with similar mixtures to better understand the relatively limited knowledge of POM materials as functional photoresists and dielectric materials.
{"title":"Polyoxometalate Hybrid Nano-Building Blocks for Extreme Ultra-Violet Photoresists","authors":"Brandon Hardie, M. Roll","doi":"10.1109/WMED.2017.7916932","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916932","url":null,"abstract":"Extreme Ultra-violet Lithography (EUVL), regardless of some setbacks, has continued its push as a viable option for next generation nodes of photolithography. Utilizing a 13.5nm wavelength, EUV is still showing promise as a natural progression of optical lithography in the semiconductor industry. Despite this upside, EUVL also has its drawbacks, one of which includes the development of a suitable photoresist material. The development and characterization of polyoxometalate (POM) hybrid nano-building blocks (NBBs) shows great potential as a candidate for improving the patterning of semiconductor devices using EUVL. Octamolybdate macromolecules were synthesized using literature methods. These primary materials were modified for improvements using a combination of physical mixtures with photoacids (resist sensitivity) and epoxide (mechanical stability). In addition, tellurium atoms (EUV absorption) were incorporated chemically and will be explored with similar mixtures to better understand the relatively limited knowledge of POM materials as functional photoresists and dielectric materials.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"127 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126245693","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}
Pub Date : 2017-04-01DOI: 10.1109/WMED.2017.7916933
Dmitrij G. Coombs, M. Hagmann
A mode-locked ultrafast laser focused on the tunneling junction of a scanning tunneling microscope (STM) superimposes harmonics of the laser pulse repetition frequency on the DC tunneling current. The power measured at each of the first 200 harmonics (up to 15 GHz) varies inversely as the square of the frequency due to stray capacitance shunting the tunneling junction. Fourier analysis suggests that in the tunneling junction the harmonics have no significant decay up to a frequency of 1/2τ ≈ 33 THz where τ = 15 fs, the laser pulse width. Two different analyses will be presented to model the generation of the frequency comb within the tunneling junction. The first is based on the observed current-voltage characteristics for the nanoscale tunneling junction. The second is a solution of the time-dependent Schrödinger equation for a modulated barrier. Both analyses indicate that optical rectification of the pulsed laser radiation in the tunneling junction causes harmonics of the pulse repetition frequency of the laser and that these harmonics may extend to terahertz frequencies. It appears that the tunneling junction may be used as a sub-nm sized source of terahertz radiation. Transmission and back scattering could not be used but loading of this source by the finite conductivity of the semiconductor would cause a loss varying inversely with the carrier density. Carrier dynamics could be measured by time-domain measurements, and time-averaged carrier profiling, but presumably with finer resolution due to the sub-nm size of the terahertz source.
{"title":"Possibility of carrier profiling semiconductors by terahertz spectroscopy with terahertz radiation generated in a scanning tunneling microscope","authors":"Dmitrij G. Coombs, M. Hagmann","doi":"10.1109/WMED.2017.7916933","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916933","url":null,"abstract":"A mode-locked ultrafast laser focused on the tunneling junction of a scanning tunneling microscope (STM) superimposes harmonics of the laser pulse repetition frequency on the DC tunneling current. The power measured at each of the first 200 harmonics (up to 15 GHz) varies inversely as the square of the frequency due to stray capacitance shunting the tunneling junction. Fourier analysis suggests that in the tunneling junction the harmonics have no significant decay up to a frequency of 1/2τ ≈ 33 THz where τ = 15 fs, the laser pulse width. Two different analyses will be presented to model the generation of the frequency comb within the tunneling junction. The first is based on the observed current-voltage characteristics for the nanoscale tunneling junction. The second is a solution of the time-dependent Schrödinger equation for a modulated barrier. Both analyses indicate that optical rectification of the pulsed laser radiation in the tunneling junction causes harmonics of the pulse repetition frequency of the laser and that these harmonics may extend to terahertz frequencies. It appears that the tunneling junction may be used as a sub-nm sized source of terahertz radiation. Transmission and back scattering could not be used but loading of this source by the finite conductivity of the semiconductor would cause a loss varying inversely with the carrier density. Carrier dynamics could be measured by time-domain measurements, and time-averaged carrier profiling, but presumably with finer resolution due to the sub-nm size of the terahertz source.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114827846","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}
Pub Date : 2017-04-01DOI: 10.1109/WMED.2017.7916928
T. Birch, M. Hagmann
We are developing a new method for the carrier profiling of semiconductors that shows promise for nm-resolution which is required at the new sub-10 nm lithography nodes. A modelocked ultrafast laser focused on the tunneling junction of a scanning tunneling microscope (STM) generates a regular sequence of pulses of minority carriers in the semiconductor. Each pulse of carriers has a width equal to the laser pulse width (e.g. 15 fs). In the frequency domain, this is a microwave frequency comb (MFC) with hundreds of measurable harmonics at integer multiples of the laser pulse repetition frequency (e.g. 74 MHz). After the minority carriers diverge rapidly into the semiconductor as a Coulomb explosion, the pulses become broader and decay, so that the MFC has less power with a spectrum limited to the first few harmonics. The frequency-dependent attenuation of the MFC is determined by the resistivity of the semiconductor at the tunneling junction so SFCM is closely related to Scanning Spreading Resistance Microscopy (SSRM). Harmonics of the MFC are measured with high speed, and high accuracy because the signal-to-noise ratio is approximately 25 dB due to their extremely narrow (sub-Hz) linewidth. Now we superimpose a low-frequency signal (e.g. 10 Hz) on either the applied bias or the voltage that is applied to the piezoelectric actuators of the STM to cause sidebands at each harmonic of the MFC which are less affected by the artifacts.
{"title":"Increased versatility for carrier profiling of semiconductors by scanning frequency comb microscopy (SFCM)","authors":"T. Birch, M. Hagmann","doi":"10.1109/WMED.2017.7916928","DOIUrl":"https://doi.org/10.1109/WMED.2017.7916928","url":null,"abstract":"We are developing a new method for the carrier profiling of semiconductors that shows promise for nm-resolution which is required at the new sub-10 nm lithography nodes. A modelocked ultrafast laser focused on the tunneling junction of a scanning tunneling microscope (STM) generates a regular sequence of pulses of minority carriers in the semiconductor. Each pulse of carriers has a width equal to the laser pulse width (e.g. 15 fs). In the frequency domain, this is a microwave frequency comb (MFC) with hundreds of measurable harmonics at integer multiples of the laser pulse repetition frequency (e.g. 74 MHz). After the minority carriers diverge rapidly into the semiconductor as a Coulomb explosion, the pulses become broader and decay, so that the MFC has less power with a spectrum limited to the first few harmonics. The frequency-dependent attenuation of the MFC is determined by the resistivity of the semiconductor at the tunneling junction so SFCM is closely related to Scanning Spreading Resistance Microscopy (SSRM). Harmonics of the MFC are measured with high speed, and high accuracy because the signal-to-noise ratio is approximately 25 dB due to their extremely narrow (sub-Hz) linewidth. Now we superimpose a low-frequency signal (e.g. 10 Hz) on either the applied bias or the voltage that is applied to the piezoelectric actuators of the STM to cause sidebands at each harmonic of the MFC which are less affected by the artifacts.","PeriodicalId":287760,"journal":{"name":"2017 IEEE Workshop on Microelectronics and Electron Devices (WMED)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124104784","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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