Simulations of carbon nanotube field effect transistors. Compared with topgate mos 2 fets on a sio 2 substrate, the field effect mobility decreased for devices on hfo 2 substrates but substantially increased for devices on al 2 o 3 substrates, possibly due to substrate surface roughness. The smaller size of transistors and other parts in computer chips e. Rf performance of topgated, zerobandgap graphene field. Rf performance of topgated, zerobandgap graphene fieldeffect transistors inanc meric1, natalia baklitskaya1, philip kim2, and kenneth l. Pdf a highperformance topgate graphene fieldeffect transistor. Also, due to the thinness of the gate dielectric, a larger electric field can be generated with respect to the nanotube using a lower gate voltage. Frequency response of topgated carbon nanotube fieldeffect transistors. A carbon nanotube fieldeffect transistor cntfet refers to a fieldeffect transistor that utilizes a single carbon nanotube or an array of carbon nanotubes as the channel material instead of bulk silicon in the traditional mosfet structure. In this letter, a topgated transistorlike field effect devices manufactured from monolayer graphene is investigated to the best of our knowledge for the first time. Topgated graphene fieldeffect transistors with high. Topgated silicon nanowire transistors are fabricated by preparing all terminals source, drain, and gate on top of the nanowire in a single step via dosemodulated ebeam lithography.
New top gated devices are being also developed at universities fig. Theoretical investigation on drain current of the topgate cnt transistor has been done by kazierski and colleagues. The threshold voltage and onset voltage for pchannel and nchannel regimes of solutionprocessed ambipolar organic transistors with topgatebottomcontact tgbc geometry were effectively tuned by gate buffer layers in between the gate electrode and the dielectric. From switches to transistors, logic gates and logic circuits hakim weatherspoon cs 3410, spring 20 computer science cornell university.
Electrochemical top gating is widely used for polymer transistors6,7, and has also been successfully applied to carbon nanotubes8,9. This is the first study that directly links the strain effect to device performance of mos2 topgated transistors. Sulpizioa department of physics, stanford university, stanford, california 94305 z. High quality hfo 2 and al 2 o 3 substrates are fabricated in order to study their impact on topgate mos 2 transistors. The results demonstrated that impedance spectroscopy applied to relatively simple topgated transistor test structures provides an approach to investigate electrically active defects at the hfo2mos2 interface and should be applicable to alternative tmd materials, surface treatments, and gate oxides as an interface defect metrology tool in the. Topgated graphene nanoribbon transistors with ultrathin. The measured carrier mobility of our monolayer devices reaches 50 cm 2 v. Pdf topgated graphene fieldeffecttransistors formed. The multiple gates may be controlled by a single gate electrode, wherein the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes. This experimental artifact has been observed before in graphene topgated transistors 10, 11.
In this work, we present evidence of tid effects in topgated epitaxial gfets. High quality hfo2 and al2o3 substrates are fabricated in order to study their impact on topgate mos2 transistors. Arrays of topgated cntfets can be fabricated on the same wafer, since the gate contacts are electrically isolated from each other, unlike in the backgated case. Request pdf high performance topgated multilayer wse2 field effect transistors in this paper, high performance topgated wse2 field effect transistor fet devices are demonstrated via a two. Highfrequency, scaled graphene transistors on diamond. Mechanically peeled graphene flakes on silicon substrate were used as the starting materials in initial studies, although the approach described here can be readily extended to graphene obtained through chemical exfoliation or chemical vapour deposition. Two kinds of methods were used to extract mobility from the measured properties of fets, and the consistent. Straingated piezotronic transistors based on vertical. This paper investigates total ionizing dose tid effects in topgated epitaxial graphene fieldeffecttransistors gfets. Topgated and bottomgated transistors with multilayer mos 2 channel fully encapsulated by stacked al 2 o 3 hfo 2 9 nm6 nm were fabricated and comparatively studied.
Polymethyl methacrylate pmma gate dielectric formed using fluorine. Current saturation in zerobandgap, topgated graphene. The integration ultrathin high dielectric constant highk materials with graphene nanoribbons gnrs for topgated transistors can push their performance limit for nanoscale electronics. Shepard1 1department of electrical engineering, columbia university, new york 10027, usa. Shepard1 1department of electrical engineering, 2department of physics, columbia university, new york, ny, 10027 email. Top gate cntfet to get better performance wind et al. Negative differential resistance in topgated chemical. Here we demonstrate a topgated graphene transistor that is able to reach doping levels of up to 5310 cm22, which is much higher than those previously reported.
Twodimensional molybdenum disulfide fieldeffect transistors. We observe an increase in mobility at lower temperatures, indicating phonon scattering may dominate over charged impurity scattering in our devices. High mobility top gated fieldeffect transistors and. The transistor was presumed to operate in the traditional depletioninversion regime, with a doping profile similar to that of a standard mosfet. Electrical characterization of topgated molybdenum disulfide fieldeffecttransistors with highk dielectrics by pavel bolshakov, peng zhao, angelica azcatl, paul k. Analyzing the effect of highk dielectricmediated doping. In summary, we have developed a new strategy to integrate highk dielectrics for topgated gnr transistors. The electronic properties of the hfo2mos2 interface were investigated using multifrequency capacitancevoltage cv and currentvoltage characterization of top gated mos2 metaloxidesemiconductor field effect transistors mosfets. Nanofabrication of topgated carbon nanotubebased transistors. Probing interface defects in topgated mos2 transistors.
Using the highk oxide nanowires as the gate dielectrics and etch mask, highperformance, topgated gnr transistors have been fabricated with the highest transconductance 29. Measurements reveal voltage shifts in the currentvoltage iv characteristics and degradation of carrier mobility and minimum conductivity, consistent with the buildup of oxidetrapped charges. High performance topgated multilayer wse2 field effect. As described in 9, practical graphene transistors must be patterned with local backgates or otherwise have individual topgate electrodes. This outperforms other timeconsuming approaches requiring alignment of multiple patterns, where alignment tolerances impose a limit on device scaling. Pdf trap density probing on topgate mos2 nanosheet fieldeffect.
The carrier mobility of our monolayer devices reaches 50 cm2vs, comparable or higher than that of mos2 counterparts 1555 cm2vs. Next, we thoroughly studied the materials and device characteristics of transistors with four different doping concentrations. The left inset shows the optical image of a singlelayer graphene connected between source and drain gold electrodes. Carbon nanotube computer chips have now outperformed the siliconbased computer chips. Single and multiwall carbon nanotube fieldeffect transistors pdf. Topgated, fewlayer graphene fieldeffect transistors fets fabricated on thermallydecomposed semiinsulating 4hsic substrates are demonstrated. Pdf twodimensional 2d molybdenum disulfide mos2 fieldeffect transistors fets have been extensively studied, but most of fets with. Here we report the fabrication of highperformance topgated fieldeffect transistors fets and related logic gates from monolayer tin disulfide sns2, a type of nontransition metal dichalcogenide. A carbon nanotube fieldeffect transistor cntfet refers to a fieldeffect transistor that utilizes. Performance limits of the selfaligned nanowire topgated. Figure 2a is the i dsv gs transfer characteristics of a mos 2 transistor with a top gate dielectric of al 2o 3. Top and side gated epitaxial graphene field effect transistors xuebin li1, xiaosong wu1, mike sprinkle1, fan ming1, ming ruan1, yike hu1, claire berger, 1, 2 and walt a.
The topgated mos 2 transistor with al 2 o 3 as both top gate dielectric and bottom passivation layer exhibits excellent electrical characteristics with an onoff ratio of. Here we report the assembly of sihfo 2 coreshell nanowires on top of individual gnrs as the topgates for gnr fieldeffect transistors with ultrathin highk dielectrics. Current saturation in zerobandgap, top gated graphene. The integration ultrathin high dielectric constant highk materials with graphene nanoribbons gnrs for top gated transistors can push their performance limit for nanoscale electronics. High performance topgated graphene nanoribbon transistors. Negative differential resistance in topgated chemical vapor deposition grown graphene transistors pankaj sharma, laurent syavoch bernard, antonios bazigos, arnaud magrez and adrian m. Moreover, the thick dielectric layers in backgated gfets are highly vulnerable to radiationinduced charge buildup. Using hfo2 as a gate dielectric, monolayer topgated cvd mos2 fets on si3n4 achieve current densities of 55 mu amu m and a transconductance of 6. A multigate device, multigate mosfet or multigate fieldeffect transistor mugfet refers to a mosfet metaloxidesemiconductor fieldeffect transistor that incorporates more than one gate into a single device. Topgated chemical vapor deposited mos2 fieldeffect. First, back or dualgated fet is not compatible with integrated circuit technology as it cannot individually tune each device like a topgate.
Figure 1 electrochemically topgated graphene transistor. A semiempirical approach for modeling radiationinduced degradation in. Electrical characterization of topgated molybdenum. Physical vapor deposited sio2 is used as the gate dielectric. Highperformance topgated monolayer sns2 fieldeffect. The transistors present typical ntype fieldeffect properties, especially with high carrier mobility up to about 36. Measurement of mobility in dualgated mos2 transistors. While power mosfets can betested satisfactorily on most curve tracers, the controls of these instruments are generally labeled with reference to bipolar transistors, and the procedure to follow in the. Control of threshold voltage for topgated ambipolar field. The electronic properties of the hfo2mos2 interface were investigated using multifrequency capacitancevoltage cv and currentvoltage characterization of topgated mos2 metaloxidesemiconductor field effect transistors mosfets. Figure2 shows the schematic diagram of a topgated cntfet with ti source, drain, and gate electrodes. Fabrication and characterization of graphene field effect diva. Highperformance graphene fieldeffect transistors gfets are fabricated with carrier mobility of up to 5400 cm2vs and topgate efficiency of up to 120 relative to that of back gate with 285 nm sio2 simultaneously through growing highquality y2o3 gate oxide at high oxidizing temperature.
Xuebin li1, xiaosong wu1, mike sprinkle1, fan ming1, ming ruan1, yike hu1. The analysis was performed on few layer 510 mos2 mosfets fabricated using photolithographic patterning with and 8 nm hfo2 gate oxide layers. In practice, however, the mos2 transistors reported in the literature should be treated as junctionless transistors which operate in the depletionaccumulation regime. For all dc measurements, the device gate length l g is 300nm and the widths w vary from 10lmto25lm, depending on the size of the cvd mos 2 domain. Hurley topgated mos2 capacitors and transistors with highk dielectrics for interface study, 2016. Shepard1 1department of electrical engineering, columbia university, new york 10027, usa 2department of applied physics and applied mathematics, columbia university, new york 10027, usa. Here we report the fabrication of highperformance topgated fieldeffect transistors fets and related logic gates from monolayer tin disulfide sns 2, a nontransition metal dichalcogenide. Top and side gated epitaxial graphene field effect transistors. Hence comparing the schematic symbol to the pn junction in figure 4, we see the anode is the ptype semiconductor and the cathode is the ntype semiconductor. Neglecting this coupling would lead to an overestimation of the mobility by a factor c tgc bg. The circuit schematic symbol of a diode is shown in figure 5. Top and side gated epitaxial graphene field effect transistors arxiv. The analysis was performed on few layer 510 mos2 mosfets fabricated using photolithographic patterning with and 8 nm hfo2. Pdf frequency response of topgated carbon nanotube.
First kths backgate and topgate graphene fets gfets were fabricated using exfoliated graphene on 90 nm thick silicon dioxide films on. Pdf a highperformance topgate graphene fieldeffect transistor gfet is fabricated, and used for constructing a high efficient frequency doubler find. Multilayer twodimensional molybdenum disulfide mos 2 fieldeffect transistors with al 2 o 3 or hfo 2 as top gate dielectric and bottom passivation layer have been comparatively studied. Compared with topgate mos2 fets on a sio2 substrate, the field effect mobility decreased for devices on hfo2 substrates but substantially increased for devices on al2o3 substrates, possibly due to substrate surface roughness. Diode schematic symbol and actual picture of a common 1n914 diode the black stripe in the picture is the cathode. Probing electronelectron interactions in onedimensional systems j.