Pub Date : 2012-06-18DOI: 10.1109/DRC.2012.6256997
S. Mittal, S. Gupta, A. Nainani, M. Abraham, K. Schuegraf, S. Lodha, U. Ganguly
Device variability has become a major concern for CMOS technology [1]. Various sources of variability include Random Dopant Fluctuation (RDF), Gate Edge Roughness (GER) and Line Edge Roughness (LER) [2]. The introduction of FinFETs at 22nm node has two issues. Firstly, the effect of RDF is considerably reduced due to undoped fins [3]. But the aggressive fin width (Wfin) requirement (~Lg/3 [4]) to reduce short channel effect aggravates the electrical impact of LER and makes it greatest contributor to patterning induced variability [2]. Moreover, the edge roughness does not scale with technology and remains independent of the type of lithography used [5]. Secondly, multiple threshold voltage (VT) is achieved in planar technology by various patterned implant steps, which is unavailable for FinFET technology as the fin is undoped. Multiple VT transistor technology is essential for power vs. performance optimization by circuit designers [6]. In this work, we propose an alternative to conventional FinFET structure which can (a) reduce overall variability by 4× reduction in sensitivity to LER and (b) enable multiple VT by applying body bias dynamically without any costly patterned implant steps.
{"title":"Epitaxialy defined (ED) FinFET: to reduce VT variability and enable multiple VT","authors":"S. Mittal, S. Gupta, A. Nainani, M. Abraham, K. Schuegraf, S. Lodha, U. Ganguly","doi":"10.1109/DRC.2012.6256997","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256997","url":null,"abstract":"Device variability has become a major concern for CMOS technology [1]. Various sources of variability include Random Dopant Fluctuation (RDF), Gate Edge Roughness (GER) and Line Edge Roughness (LER) [2]. The introduction of FinFETs at 22nm node has two issues. Firstly, the effect of RDF is considerably reduced due to undoped fins [3]. But the aggressive fin width (Wfin) requirement (~Lg/3 [4]) to reduce short channel effect aggravates the electrical impact of LER and makes it greatest contributor to patterning induced variability [2]. Moreover, the edge roughness does not scale with technology and remains independent of the type of lithography used [5]. Secondly, multiple threshold voltage (VT) is achieved in planar technology by various patterned implant steps, which is unavailable for FinFET technology as the fin is undoped. Multiple VT transistor technology is essential for power vs. performance optimization by circuit designers [6]. In this work, we propose an alternative to conventional FinFET structure which can (a) reduce overall variability by 4× reduction in sensitivity to LER and (b) enable multiple VT by applying body bias dynamically without any costly patterned implant steps.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"10 1","pages":"127-128"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90991301","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256932
D. Reddy, L. Register, S. Banerjee
Electronic devices have been explored in the past based on resonant single-electron CB (conduction band) to CB tunneling between parallel quasi-two dimensional (2D) quantum wells within III-V heterostructures and their accompanying negative differential resistance (NDR) [1]. Such devices are attractive for high speed electronics, and digital logic circuits also have been demonstrated using a combination of conventional and such NDR FETs [2]. For two graphene layers separated by a tunnel barrier, we recently proposed the ultra-low-voltage Bilayer pseudoSpin FET (BiSFET) which would employ enhanced nonresonant VB (valence band) to CB tunneling, with a nevertheless very sharp NDR characteristic based on a predicted room-temperature many-body superfluid state [3]. However, NDR due to resonant single-particle CB-to-CB or VB-to-VB tunneling may also be achievable in such a structure. Furthermore, the atomically near-perfect 2D nature of the component graphene layers and the conduction/valence band symmetry may offer advantages over III-Vs. Here, we model the I-V characteristics due to single-particle tunneling in such a structure, Fig. 1, using a perturbative tunneling Hamiltonian approach [4,5], and deviations from this simple theory using atomistic tight-binding nonequilibrium Green's function (NEGF) simulation.
{"title":"Bilayer graphene vertical tunneling field effect transistor","authors":"D. Reddy, L. Register, S. Banerjee","doi":"10.1109/DRC.2012.6256932","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256932","url":null,"abstract":"Electronic devices have been explored in the past based on resonant single-electron CB (conduction band) to CB tunneling between parallel quasi-two dimensional (2D) quantum wells within III-V heterostructures and their accompanying negative differential resistance (NDR) [1]. Such devices are attractive for high speed electronics, and digital logic circuits also have been demonstrated using a combination of conventional and such NDR FETs [2]. For two graphene layers separated by a tunnel barrier, we recently proposed the ultra-low-voltage Bilayer pseudoSpin FET (BiSFET) which would employ enhanced nonresonant VB (valence band) to CB tunneling, with a nevertheless very sharp NDR characteristic based on a predicted room-temperature many-body superfluid state [3]. However, NDR due to resonant single-particle CB-to-CB or VB-to-VB tunneling may also be achievable in such a structure. Furthermore, the atomically near-perfect 2D nature of the component graphene layers and the conduction/valence band symmetry may offer advantages over III-Vs. Here, we model the I-V characteristics due to single-particle tunneling in such a structure, Fig. 1, using a perturbative tunneling Hamiltonian approach [4,5], and deviations from this simple theory using atomistic tight-binding nonequilibrium Green's function (NEGF) simulation.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"23 1","pages":"73-74"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87275691","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 : 2012-06-18DOI: 10.1109/DRC.2012.6257008
B. Radisavljevic, Daria Krasnozhon, M. Whitwick, A. Kis
Two-dimensional crystals offer several inherent advantages over conventional 3D electronic materials or 1D nanomaterials such as nanotubes and nanowires. Their planar geometry makes it easier to fabricate circuits and complex structures by tailoring 2D layers into desired shapes. Because of their atomic scale thickness, 2D materials also represent the ultimate limit of miniaturization in the vertical dimension and allow the fabrication of shorter transistors due to enhanced electrostatic control. Another advantage of 2D semiconductors is that their electronic properties (band gap, mobility, work function) can be tuned for example by changing the number of layers or applying external electric fields.
{"title":"MoS2-based devices and circuits","authors":"B. Radisavljevic, Daria Krasnozhon, M. Whitwick, A. Kis","doi":"10.1109/DRC.2012.6257008","DOIUrl":"https://doi.org/10.1109/DRC.2012.6257008","url":null,"abstract":"Two-dimensional crystals offer several inherent advantages over conventional 3D electronic materials or 1D nanomaterials such as nanotubes and nanowires. Their planar geometry makes it easier to fabricate circuits and complex structures by tailoring 2D layers into desired shapes. Because of their atomic scale thickness, 2D materials also represent the ultimate limit of miniaturization in the vertical dimension and allow the fabrication of shorter transistors due to enhanced electrostatic control. Another advantage of 2D semiconductors is that their electronic properties (band gap, mobility, work function) can be tuned for example by changing the number of layers or applying external electric fields.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"72 1","pages":"179-180"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75064180","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 : 2012-06-18DOI: 10.1109/DRC.2012.6257028
M. Lemme, S. Vaziri, A. D. Smith, M. Ostling
The future manufacturability of graphene devices depends on the availability of large-scale graphene fabrication methods. While chemical vapor deposition and epitaxy from silicon carbide both promise scalability, they are not (yet) fully compatible with silicon technology. Direct growth of graphene on insulating substrates would be a major step, but is still at a very early stage [1]. This has implications on potential entry points of graphene as an add-on to mainstream silicon technology, which will be discussed in the talk.
{"title":"Alternative graphene devices: beyond field effect transistors","authors":"M. Lemme, S. Vaziri, A. D. Smith, M. Ostling","doi":"10.1109/DRC.2012.6257028","DOIUrl":"https://doi.org/10.1109/DRC.2012.6257028","url":null,"abstract":"The future manufacturability of graphene devices depends on the availability of large-scale graphene fabrication methods. While chemical vapor deposition and epitaxy from silicon carbide both promise scalability, they are not (yet) fully compatible with silicon technology. Direct growth of graphene on insulating substrates would be a major step, but is still at a very early stage [1]. This has implications on potential entry points of graphene as an add-on to mainstream silicon technology, which will be discussed in the talk.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"70 1","pages":"24a-24b"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74668218","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 : 2012-06-18DOI: 10.1109/DRC.2012.6257013
M. Shatalov, Wenhong Sun, A. Lunev, Xuhong Hu, A. Dobrinsky, Y. Bilenko, Jinwei Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, M. Wraback
III-Nitride based deep ultraviolet (DUV) light emitting diodes (LEDs) offer smaller size, wider choice of peak emission wavelengths, lower power consumption and reduced cost compared to mercury vapor lamps and other UV light sources. Increasing efficiency of DUV LEDs accelerates their applications in bio-agent detection, analytical instrumentation, phototherapy, disinfection, biotechnology and sensing. We report on 278 nm DUV LEDs with external quantum efficiency exceeding 10 % achieved by improvements of material quality and light extraction.
{"title":"278 nm deep ultraviolet LEDs with 11% external quantum efficiency","authors":"M. Shatalov, Wenhong Sun, A. Lunev, Xuhong Hu, A. Dobrinsky, Y. Bilenko, Jinwei Yang, M. Shur, R. Gaska, C. Moe, G. Garrett, M. Wraback","doi":"10.1109/DRC.2012.6257013","DOIUrl":"https://doi.org/10.1109/DRC.2012.6257013","url":null,"abstract":"III-Nitride based deep ultraviolet (DUV) light emitting diodes (LEDs) offer smaller size, wider choice of peak emission wavelengths, lower power consumption and reduced cost compared to mercury vapor lamps and other UV light sources. Increasing efficiency of DUV LEDs accelerates their applications in bio-agent detection, analytical instrumentation, phototherapy, disinfection, biotechnology and sensing. We report on 278 nm DUV LEDs with external quantum efficiency exceeding 10 % achieved by improvements of material quality and light extraction.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"16 1","pages":"255-256"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77706377","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256960
S. Bhave
Opto-mechanical systems offer one of the most sensitive methods for detecting mechanical motion using shifts in the optical resonance frequency of the optomechanical resonator. Presently, these systems are used for measuring mechanical thermal noise displacement or mechanical motion actuated by optical forces. Meanwhile, electrostatic capacitive actuation and detection is the main transduction scheme used in RF MEMS resonators. The use of electrostatics is convenient as it allows direct integration with electronics used for processing the RF signals. In this presentation, the author will introduce a method for actuating an opto-mechanical resonator using electrostatic forces and sensing of mechanical motion by using the optical intensity modulation at the output of an optomechanical resonator, integrated into a monolithic system fabricated on a silicon-on-insulator (SOI) platform. The author will discuss new applications enabled by this hybrid system including opto-acoustic oscillators and opto-mechanical accelerometers.
{"title":"Silicon monolithic MEMS + photonic systems","authors":"S. Bhave","doi":"10.1109/DRC.2012.6256960","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256960","url":null,"abstract":"Opto-mechanical systems offer one of the most sensitive methods for detecting mechanical motion using shifts in the optical resonance frequency of the optomechanical resonator. Presently, these systems are used for measuring mechanical thermal noise displacement or mechanical motion actuated by optical forces. Meanwhile, electrostatic capacitive actuation and detection is the main transduction scheme used in RF MEMS resonators. The use of electrostatics is convenient as it allows direct integration with electronics used for processing the RF signals. In this presentation, the author will introduce a method for actuating an opto-mechanical resonator using electrostatic forces and sensing of mechanical motion by using the optical intensity modulation at the output of an optomechanical resonator, integrated into a monolithic system fabricated on a silicon-on-insulator (SOI) platform. The author will discuss new applications enabled by this hybrid system including opto-acoustic oscillators and opto-mechanical accelerometers.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"29 1","pages":"17-18"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83731519","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256965
K. Shepard
Biomolecular systems are traditionally studied using ensemble measurements and fluorescence-based detection. Among the most common in vitro applications are DNA microarrays to identify target gene expression profiles [1] and enzyme-linked immunosorbent assays (ELISA) to identify proteins [2]. While much can be determined with ensemble measurements, scientific and technological interest is rapidly moving to single-molecule techniques. When probing at the single-molecule level, observations can be made about the inter- and intramolecular dynamics that are usually hidden in ensemble measurements. In molecular diagnostic, single-molecule techniques often do not require amplification and simplify sample preparation. The most popular single-molecule techniques based on fluorescence [3, 4] are fundamentally limited in resolution and bandwidth by the countable number of photons emitted by a single fluorophore (typically on the order of 2500 photons/sec). Instrumentation is complex, expensive, and large-form-factor. Furthermore, most optical probes photobleach, limiting observation times and pump powers. Single-molecule measurements of the kinetics of fast biomolecular processes are often unavailable through fluorescent techniques, as they lack the required temporal resolution.
{"title":"Solid-state electronics and single-molecule biophysics","authors":"K. Shepard","doi":"10.1109/DRC.2012.6256965","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256965","url":null,"abstract":"Biomolecular systems are traditionally studied using ensemble measurements and fluorescence-based detection. Among the most common in vitro applications are DNA microarrays to identify target gene expression profiles [1] and enzyme-linked immunosorbent assays (ELISA) to identify proteins [2]. While much can be determined with ensemble measurements, scientific and technological interest is rapidly moving to single-molecule techniques. When probing at the single-molecule level, observations can be made about the inter- and intramolecular dynamics that are usually hidden in ensemble measurements. In molecular diagnostic, single-molecule techniques often do not require amplification and simplify sample preparation. The most popular single-molecule techniques based on fluorescence [3, 4] are fundamentally limited in resolution and bandwidth by the countable number of photons emitted by a single fluorophore (typically on the order of 2500 photons/sec). Instrumentation is complex, expensive, and large-form-factor. Furthermore, most optical probes photobleach, limiting observation times and pump powers. Single-molecule measurements of the kinetics of fast biomolecular processes are often unavailable through fluorescent techniques, as they lack the required temporal resolution.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"11 1","pages":"7-8"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85648410","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256933
E. Harvard, J. Shealy
In conclusion, we present an AIGaN/GaN HEMT which exhibits a high off-state breakdown voltage with small features and without a field plate, while maintaining high bandwidth. High voltage load line mapping of these devices at 2 GHz is in progress.
{"title":"440 V AlSiN-passivated AlGaN/GaN high electron mobility transistor with 40 GHz bandwidth","authors":"E. Harvard, J. Shealy","doi":"10.1109/DRC.2012.6256933","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256933","url":null,"abstract":"In conclusion, we present an AIGaN/GaN HEMT which exhibits a high off-state breakdown voltage with small features and without a field plate, while maintaining high bandwidth. High voltage load line mapping of these devices at 2 GHz is in progress.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"14 1","pages":"75-76"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87798139","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256974
M. Ebrish, S. Koester
The temperature-dependent C-V characteristics for two samples with target HfO2 thicknesses of 20 nm (sample A), and 10 nm (sample B) are shown in Figs. 2 and 3. The results show that the capacitance tuning range increases with decreasing HfO2 thicknesses, as expected. A comparison of the normalized C-V curves for both samples at room temperature is shown in Fig. 4. The capacitance tuning range from Vg - VDirac = 0 to +1.5 V is 1.17:1 for sample A and 1.38:1 for sample B. Fig. 5 shows a comparison of the C-V characteristics for the varactors with MIM capacitors fabricated on the same sample. A very consistent trend is observed where the capacitance-per-unit-area for the MIM capacitors is significantly higher than for the varactors. The EOT values extracted from the MIM capacitors are found to be 4.1 nm and 2.7 nm for samples A and B, respectively. In order to understand this behavior in more detail, numerical modeling was performed on the temperature-dependent C-V characteristics where the random potential fluctuations, σ, in the graphene was used as an adjustable fitting parameter [5]. The results are shown in Fig. 6. The fact that the fitted EOT values cannot completely account for the capacitance reduction in Fig. 5 is a strong indicator that the effective device area of the varactors is less than the layout area. However, additional modeling, particularly taking into account the effect of interface traps, and other imperfections between the graphene and HfO2 [6-7] is needed to fully understand the observed behavior. In the future, further scaling of the EOT needs to be investigated, as well as fabrication of the devices on insulating substrates for eventual use in resonator circuits. As a preliminary demonstration (Fig. 7), we have fabricated a single-finger varactor on a quartz substrate, with EOT (as determined by MIM capacitors) of 1.9 nm and tuning range >;1.5:1 at room temperature.
{"title":"Dielectric thickness dependence of quantum capacitance in graphene varactors with local metal back gates","authors":"M. Ebrish, S. Koester","doi":"10.1109/DRC.2012.6256974","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256974","url":null,"abstract":"The temperature-dependent C-V characteristics for two samples with target HfO2 thicknesses of 20 nm (sample A), and 10 nm (sample B) are shown in Figs. 2 and 3. The results show that the capacitance tuning range increases with decreasing HfO2 thicknesses, as expected. A comparison of the normalized C-V curves for both samples at room temperature is shown in Fig. 4. The capacitance tuning range from Vg - VDirac = 0 to +1.5 V is 1.17:1 for sample A and 1.38:1 for sample B. Fig. 5 shows a comparison of the C-V characteristics for the varactors with MIM capacitors fabricated on the same sample. A very consistent trend is observed where the capacitance-per-unit-area for the MIM capacitors is significantly higher than for the varactors. The EOT values extracted from the MIM capacitors are found to be 4.1 nm and 2.7 nm for samples A and B, respectively. In order to understand this behavior in more detail, numerical modeling was performed on the temperature-dependent C-V characteristics where the random potential fluctuations, σ, in the graphene was used as an adjustable fitting parameter [5]. The results are shown in Fig. 6. The fact that the fitted EOT values cannot completely account for the capacitance reduction in Fig. 5 is a strong indicator that the effective device area of the varactors is less than the layout area. However, additional modeling, particularly taking into account the effect of interface traps, and other imperfections between the graphene and HfO2 [6-7] is needed to fully understand the observed behavior. In the future, further scaling of the EOT needs to be investigated, as well as fabrication of the devices on insulating substrates for eventual use in resonator circuits. As a preliminary demonstration (Fig. 7), we have fabricated a single-finger varactor on a quartz substrate, with EOT (as determined by MIM capacitors) of 1.9 nm and tuning range >;1.5:1 at room temperature.","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"7 1","pages":"105-106"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85942949","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 : 2012-06-18DOI: 10.1109/DRC.2012.6256983
A. Talukdar, M. Qazi, G. Koley
Summary form only given.We report, for the first time, an ultra high gauge factor of more than 3500 observed using AlGaN/GaN Heterostructure Field Effect Transistor (HFET) embedded GaN piezoresistive microcantilever. In addition, the deflection transduction signal from the HFET was utilized to determine dynamic bending as well as AC frequency response of the cantilever. Finally, the piezoresistive microcantilver was used to detect very small acoustic pressure waves generated by a piezo chip oscillated at sub nm amplitude at the resonance frequency of the cantilever positioned 1 cm away, highlighting the utility of these cantilevers as highly sensitive ultrasonic transducers. FET embedded microcantilevers are ideal for developing integrated electronic detection platform for biological and chemical analytes. GaN microcantilever with integrated AlGaN/GaN HFET deflection transducer offers very high mechanical, thermal, and chemical stability, in addition to extraordinary deflection sensitivity due to its strong piezoelectric properties. The piezoelectric property of III-V Nitrides causes a highly mobile (>;1500 cm2/Vs) two dimensional electron gas (2DEG) to form at the AlGaN/GaN interface, which gets strongly affected by the deflection induced strain. In addition, the electron mobility also changes due to the change in effective mass. The combined changes in 2DEG and mobility offer very high deflection sensitivity, verified through COMSOL finite element simulations and experimental observations. The effect of mechanical strain caused by microcantilever bending on the 2DEG and the AlGaN/GaN HFET characteristics has been reported experimentally [1] and theoretically [2] earlier, but this for the first time we have obtained such a high Gauge Factor. Microcantilevers were fabricated using III-V Nitride layers on Si(111). The layer structure consisted of i-GaN (2 nm)/ AlGaN (17.5 nm, 26% Al)/i-GaN (1 μm)/Transition layer (1.1 μm)/Si (111) substrate (500 μm). Fig. 1 (a) shows the SEM image of the fabricated device with the HFET shown in the inset. The HFET was fabricated with initial 200 nm mesa etching, followed by Ti(20 nm)/Al(100 nm)/Ti(45 nm)/Au(55 nm) metal stack deposition and rapid thermal annealing for ohmic contact formation. For gate contact, Ni(25 nm)/Au(375 nm) Schottky barrier was used. The fabricated microcantilever dimension is 350×50×2 μm. The GaN cantilever pattern was etched down using Ch based inductively coupled plasma etch process. Fig. 1 (b) shows the schematics of the experimental setup using our wire bonded device (shown as inset in Fig. 2) and Nanopositioner's (PI-611 Z). Fig. 2 shows the Id-V d characteristics of one of our best devices for different gate bias. In Fig. 3 the static bending performance is shown where the drain current is found to change by 6.3 % in magnitude, which gives a gauge factor of 3532. Both the downward and upward bending of cantilever exhibited similar changes. The movement of the nanopositioner was contr
{"title":"Highly sensitive III–V nitride based piezoresistive microcantilever using embedded AlGaN/GaN HFET as ultrasonic detector","authors":"A. Talukdar, M. Qazi, G. Koley","doi":"10.1109/DRC.2012.6256983","DOIUrl":"https://doi.org/10.1109/DRC.2012.6256983","url":null,"abstract":"Summary form only given.We report, for the first time, an ultra high gauge factor of more than 3500 observed using AlGaN/GaN Heterostructure Field Effect Transistor (HFET) embedded GaN piezoresistive microcantilever. In addition, the deflection transduction signal from the HFET was utilized to determine dynamic bending as well as AC frequency response of the cantilever. Finally, the piezoresistive microcantilver was used to detect very small acoustic pressure waves generated by a piezo chip oscillated at sub nm amplitude at the resonance frequency of the cantilever positioned 1 cm away, highlighting the utility of these cantilevers as highly sensitive ultrasonic transducers. FET embedded microcantilevers are ideal for developing integrated electronic detection platform for biological and chemical analytes. GaN microcantilever with integrated AlGaN/GaN HFET deflection transducer offers very high mechanical, thermal, and chemical stability, in addition to extraordinary deflection sensitivity due to its strong piezoelectric properties. The piezoelectric property of III-V Nitrides causes a highly mobile (>;1500 cm2/Vs) two dimensional electron gas (2DEG) to form at the AlGaN/GaN interface, which gets strongly affected by the deflection induced strain. In addition, the electron mobility also changes due to the change in effective mass. The combined changes in 2DEG and mobility offer very high deflection sensitivity, verified through COMSOL finite element simulations and experimental observations. The effect of mechanical strain caused by microcantilever bending on the 2DEG and the AlGaN/GaN HFET characteristics has been reported experimentally [1] and theoretically [2] earlier, but this for the first time we have obtained such a high Gauge Factor. Microcantilevers were fabricated using III-V Nitride layers on Si(111). The layer structure consisted of i-GaN (2 nm)/ AlGaN (17.5 nm, 26% Al)/i-GaN (1 μm)/Transition layer (1.1 μm)/Si (111) substrate (500 μm). Fig. 1 (a) shows the SEM image of the fabricated device with the HFET shown in the inset. The HFET was fabricated with initial 200 nm mesa etching, followed by Ti(20 nm)/Al(100 nm)/Ti(45 nm)/Au(55 nm) metal stack deposition and rapid thermal annealing for ohmic contact formation. For gate contact, Ni(25 nm)/Au(375 nm) Schottky barrier was used. The fabricated microcantilever dimension is 350×50×2 μm. The GaN cantilever pattern was etched down using Ch based inductively coupled plasma etch process. Fig. 1 (b) shows the schematics of the experimental setup using our wire bonded device (shown as inset in Fig. 2) and Nanopositioner's (PI-611 Z). Fig. 2 shows the Id-V d characteristics of one of our best devices for different gate bias. In Fig. 3 the static bending performance is shown where the drain current is found to change by 6.3 % in magnitude, which gives a gauge factor of 3532. Both the downward and upward bending of cantilever exhibited similar changes. The movement of the nanopositioner was contr","PeriodicalId":6808,"journal":{"name":"70th Device Research Conference","volume":"1 1","pages":"19-20"},"PeriodicalIF":0.0,"publicationDate":"2012-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82947284","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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