Unique Characteristics of Vertical Carbon Nanotube Field-effect Transistors on Silicon

A vertical carbon nanotube field-effect transistor(CNTFET) based on silicon(Si) substrate has been proposed and simulated using a semi-classical theory. A single-walled carbon nanotube(SWNT) and an n-type Si nanowire in series construct the channel of the transistor. The CNTFET presents ambipolar characteristics at positive drain voltage(Vd) and n-type characteristics at negative Vd. The current is significantly influenced by the doping level of n-Si and the SWNT band gap. The n-branch current of the ambipolar characteristics increases with increasing doping level of the n-Si while the p-branch current decreases. The SWNT band gap has the same influence on the p-branch current at a positive Vd and n-type characteristics at negative Vd. The lower the SWNT band gap, the higher the current. However, it has no impact on the n-branch current in the ambipolar characteristics. Thick oxide is found to significantly degrade the current and the subthreshold slope of the CNTFETs.

Study on the Carbon Nanotube Separative Structure for the Extended Gate H^+-Ion Sensitive Field Effect Transistor

We use the carbon nanotube (CNT) as the material of the pH sensing layer of the separative structure for the extended gate H^+-ion sensitive field effect transistor (EGFET) device.The CNT paste was prepared with CNT powder,Ag powder,silicagel,the di-n-butyl phthalate and the toluene solvents by appropriate ratio,then immobilized on the silicon substrate to form the carbon nanotube sensing layer.We measured theⅠ_(DS)-Ⅴ_G curves of the carbon nanotube separative structure EGFET device in the different pH buffer solutions by the Keithley 236Ⅰ-Ⅴmeasurement system.According to the experimental results,we can obtain the pH sensitivities of the carbon nanotube separative structure EGFET device,which is 62.54mV/pH from pH1 to pH13.

Design of Multi-Valued Logic Circuit Using Carbon Nano Tube Field Transistors

The design of a three-input logic circuit using carbon nanotube field effect transistors(CNTFETs)is presented.Ternary logic must be an exact replacement for dual logic since it performs straightforwardly in digital devices,which is why this design is so popular,and it also reduces chip area,both of which are examples of circuit overheads.The proposed module we have investigated is a triple-logic-based one,based on advanced technology CNTFETs and an emphasis on minimizing delay times at various values,as well as comparisons of the design working with various load capacitances.Comparing the proposed design with the existing design,the delay times was reduced from 66.32 to 16.41 ps,i.e.,a 75.26%reduction.However,the power dissipation was not optimized,and increased by 1.44%compared to the existing adder.The number of transistors was also reduced,and the product of power and delay(P∗D)achieved a value of 0.0498053 fJ.An improvement at 1 V was also achieved.A load capacitance(fF)was measured at different values,and the average delay measured for different values of capacitance had a maximum of 83.60 ps and a minimum of 22.54 ps,with a range of 61.06 ps.The power dissipations ranged from a minimum of 3.38μW to a maximum of 6.49μW.Based on these results,the use of this CNTFET half-adder design in multiple Boolean circuits will be a useful addition to circuit design.

Electronic Detection of Escherichia coli O157︰H7 Using Single-Walled Carbon Nanotubes Field-Effect Transistor Biosensor

Field effect transistors (FET) based on Single-Walled Carbon Nanotubes (SWNTs) become the hot topic in fields of nano-electronic, clinical diagnostics, environmental testing etc. in recent years. In this paper, we reported a simple, scalable way to enrich semiconducting SWNTs by using HNO3/H2SO4. Then carbon nanotube field-effect transistors (CNTFET) biosensor was fabricated with the enrichment SWNTs for Escherichia coli O157︰H7 detection. The response of each CNTFET was monitored in real time before and after introduction of the Escherichia coli O157︰H7 at various concentrations. The results show that CNT-FET biosensors we fabricated are sensitive to change of concentration of solution and response time is really short.

A voltage-controlled chaotic oscillator based on carbon nanotube field-effect transistor for low-power embedded systems

This paper presents a compact and low-power-based discrete-time chaotic oscillator based on a carbon nanotube fieldeffect transistor implemented using Wong and Deng's well-known model. The chaotic circuit is composed of a nonlinear circuit that creates an adjustable chaos map, two sample and hold cells for capture and delay functions, and a voltage shifter that works as a buffer and adjusts the output voltage for feedback. The operation of the chaotic circuit is verified with the SPICE software package, which uses a supply voltage of 0.9 V at a frequency of 20 kHz. The time series, frequency spectra, transitions in phase space, sensitivity with the initial condition diagrams, and bifurcation phenomena are presented.The main advantage of this circuit is that its chaotic signal can be generated while dissipating approximately 7.8 μW of power, making it suitable for embedded systems where many chaos-signal generators are required on a single chip.

Designing a Carbon Nanotube Field-Effect Transistor with High Transition Frequency for Ultra-Wideband Application

Theoretical calculations predict transition frequencies in the terahertz range for the field-effect transistors based on carbon nanotubes, and this shows their suitability for being used in high frequency applications. In this paper, we have designed a field-effect transistor based on carbon nanotube with high transition frequency suitable for ultra-wide band applications. We did this by optimizing nanotube diameter, gate insulator thickness and dielectric constant. As a result, we achieved the transition frequency about 7.45 THz. The environment of open source software FETToy is used to simulate the device. Also a suitable model for calculating the transition frequency is presented.

Performances of carbon nanotube field effect transistors with altered channel length

The influence of channel length on the performances of carbon nanotube field effect transistors(CNT-FETs) has been studied.Buffered oxide etching was used to remove approximately a 60 nm layer from the original 100 nm silicon dioxide layer,to thin the dielectric layer of the back gate.Channel length of the CNT-FETs was changed along with the etching process.The dependence of drain-source current on gate voltage was measured to analyze the performance of the CNT-FETs,including the transconductance,carrier mobility,current ON/OFF ratio,etc.The results indicate that the devices still keep good quality.

High yield fabrication of semiconducting thin-film field-effect transistors based on chemically functionalized single-walled carbon nanotubes

Here we report a simple and scalable method to fabricate high performance thin-film field-effect transistors(FETs) with high yield based on chemically functionalized single-walled carbon nanotubes(SWNTs) by organic radical initiators.The UV-Vis-NIR spectra,Raman spectra and electrical characterization demonstrated that metallic species in CoMoCat 65 and HiPco SWNTs could be effectively eliminated after reaction with some organic radical initiators.The effects of the substrate properties on the electrical properties of FET devices were investigated,and the results showed that the electrical properties of FET devices fabricated on high hydrophobic substrates were better than those on low hydrophobic substrates.Furthermore,it was found that FET devices based on 1,1'-azobis(cyanocyclohexane)(ACN)-modified CoMoCat 65 SWNTs exhibited more excellent electrical performance with effective mobility of ～11.8 cm2/Vs and on/off ratio of ～2×105 as compared with benzoyl peroxide(BPO)-modified CoMoCat 65 SWNTs and lauoryl peroxideand(LPO)-modified HiPco SWNTs,likely due to the introduction of the electron-withdrawing groups(CN group) on the SWNT surface.This method does not require nontrivial reaction conditions or complicated purification after reaction,therefore promising low-cost production of high-performance devices for macroelectronics.

Field-effect transistors with multiple channels constructed by carbon nanotubes

Single-wall carbon nanotubes (SWNTs) pre-decorated with functional molecules are directly aligned in the AC electric field, which makes SWNTs parallelly bridge the source and drain electrodes and act as the multiple conduction channels of the field-effect transistor (FET). The method avoids the mutual tanglement of SWNTs and makes them align between the source and drain electrodes abreast and dispersedly. It is indicated that aligning SWNTs in the high-volatility solvents can decrease the contaminant around the electrodes and has a function to purify the raw SWNTs. The obtained multi-channel FET not only takes on a high transconductance, but also holds the good reliability and stability.

Sorting Semiconducting Single-Walled Carbon Nanotubes by Water-Soluble Polyfluorene Assisted Electrophoresis and Its Application in Field-effect Transistors

我们基于 agarose 胶化电气泳动(年龄) 报导一个更加有希望的方法由作为表面活化剂增加水溶性的 polyfluorene (w-PFO ) 进 agarose 胶化分开围单人赛的碳 nanotubes。在这个有效方法， AGE/w-PFO 胶化网络将与 w-PFO 的帮助套住更半导体的围单人赛的碳 nanotubes (SWNT ) ，为在 w-PFO 和半导体的种类之间的强壮的相互作用。光吸收度，光致发光排放和反响的拉曼散布描述被用来验证分离效果。分开的半导体的种类的纯净高象一样(98 ±1 )% 。表明的地效果晶体管分别地给开／关比率和活动性大约 27000 和 10.2 厘米 2·V−1·s−1, 。

Assessment of High-Frequency Performance Limits of Graphene Field-Effect Transistors

晶体管(联邦货物税) 击倒到 20 nm 的隧道长度的 graphene 地效果的高频率表演限制被使用前後一致的量模拟检验了。结果比 3 在 20 nm 的隧道长度弄平的显示尽管克莱因 band-to-band 通道为 sub-100 nm graphene 联邦货物税是重要的，完成好跨导和大的弹道的开关比率是可能的。在 20 nm 的隧道长度，内在的截止频率为各种各样的门绝缘体厚度价值在一些 THz 留下，但是薄门绝缘体面对寄生电容为好跨导和截止频率的更小的降级是必要的。内在的截止频率接近 graphene 给运动电感(L) 和量电容(C) 的 LC 典型频率，哪个是大约 100 GHz 牰灯牥楴獥 ? ю ? ю吗？

Alignment of Nanoscale Single-Walled Carbon Nanotubes Strands

Depositing single-walled carbon nanotubes(SWNTs) with controllable density, pattern and orientation on electrodes presents a challenge in today's research. Here, we report a novel solvent evaporation method to align SWNTs in patterns having nanoscale width and micronscale length. SWNTs suspension has been introduced dropwise onto photoresist resin microchannels; and the capillary force can stretch and align SWNTs into strands with nanoscale width in the microchannels. Then these narrow and long aligned SWNTs patterns were successfully transferred to a pair of gold electrodes with different gaps to fabricate carbon nanotube field-effect transistor(CNTFET). Moreover, the electrical performance of the CNTFET show that the SWNTs strands can bridge different gaps and fabricate good electrical performance CNTFET with ON/OFF ratio around 106. This result suggests a promising and simple strategy for assembling well-aligned SWNTs into CNTFET device with good electrical performance.

Carbon nanomaterials： controlled growth and field-effect transistor biosensors

包括碳 nanotubes (CNT ) 和 graphene，碳 nanostructures 由于他们的特殊结构，优秀电的性质和高化学的稳定性广泛地被学习了。与纳米技术和 nanoscience 的发展，各种各样的方法被开发了综合 CNTs/graphene 并且装配他们进 microelectronic/sensor 设备。在这评论，我们主要为生物传感器在地效果晶体管(联邦货物税) 在 CNT 和 graphene 和他们的应用程序的合成表明最近的进步。

碳纳米管薄膜场效应晶体管低温电学特性

基于网络状碳纳米管(carbon nanotube,CNT)薄膜制备了网络状碳纳米管薄膜场效应晶体管(carbon nanotube thin film field effect transistor,CNT-TFT),研究了温度为100~300 K时,CNT-TFT的电学特性,并对关键电学参数,如开态电流I_(on)、跨导G_(m)、阈值电压V_(th)和亚阈值摆幅S_(S)等,进行了深入分析。研究结果表明,随着温度的降低,G_(m)出现了下降,V_(th)向左漂移;在G_(m)和V_(th)共同作用下,I_(on)显著下降。通过对电学参数随温度演化机制的深入分析,发现器件G_(m)的降低不仅与CNT内的散射及CNT-金属接触电阻相关,而且与交叠的碳纳米管间的结电阻密切相关。同时,研究还表明,低温下,界面俘获中心对电子俘获概率的减小是引起器件V_(th)和S_(S)变化的主要因素。

功率器件功率循环测试技术的挑战与分析

功率循环测试被称为考核功率器件封装可靠性最重要的实验,尤其是碳化硅金属–氧化物半导体场效应晶体管(silicon carbon metal-oxide-semiconductor field-effect transistor,SiC MOSFET)功率器件的快速发展,是近几年的研究热点。与其他可靠性测试不同的是,功率循环测试原理虽然简单,但测试技术、测试方法和数据处理却涉及到半导体物理、电磁学、传热学、结构力学和信号分析等多学科交叉,处理不当将得到错误的结论。文中基于功率循环测试基本原理,从测试技术、测试方法和数据处理3个大方面对其存在的挑战进行深入分析,并提出相应的解决方案。测试技术主要包括电气测量噪声、结温测量延时和数据采集点,电气测量噪声和测量延时影响功率循环测试中结温的准确性,数据采集点则是影响器件的失效模式判定和寿命。测试方法主要包括结温测试方法、电流激励方法和宽禁带器件SiC MOSFET的相关测试方法,其中电流激励方法会影响器件的失效机理和寿命,需要特别关注。数据处理部分则是从可靠性数理统计角度出发,探究测试样本数量和对测试结果的修正,以得到准确的测试结果。该文可以为功率循环测试技术和设备的发展奠定一定理论和方法基础,为功率循环测试和数据分析提供一些借鉴。

High-performance doping-free carbon-nanotube-based CMOS devices and integrated circuits

Ballistic n-type carbon nanotube(CNT)-based field-effect transistors(FETs) have been fabricated by contacting semiconducting single-walled CNTs(SWCNTs) using Sc or Y.The n-type CNT FETs were pushed to their performance limits through further optimizing their gate structure and insulator.The CNT FETs outperformed n-type Si metal-oxide-semiconductor(MOS) FETs with the same gate length and displayed better downscaling behavior than the Si MOS FETs.Together with the demonstration of ballistic p-type CNT FETs using Pd contacts,this technological advance is a step toward the doping-free fabrication of CNT-based ballistic complementary metal-oxide-semiconductor(CMOS) devices and integrated circuits.Taking full advantage of the perfectly symmetric band structure of the semiconductor SWCNT,a perfect SWCNT-based CMOS inverter was demonstrated,which had a voltage gain of over 160.Two adjacent n-and p-type FETs fabricated on the same SWCNT with a self-aligned top-gate realized high field mobility simultaneously for electrons(3000 cm2 V-1 s-1) and holes(3300 cm2 V-1 s-1).The CNT FETs also had excellent potential for high-frequency applications,such as a high-performance frequency doubler.

一种基于单壁碳纳米管网络的柔性场效应晶体管器件

针对未来可穿戴电子设备对高性能柔性场效应晶体管的迫切需求,提出一种基于单壁碳纳米管网络的柔性场效应晶体管的制备方法,采用超柔的聚酰亚胺薄膜(PI)作为衬底,以具有高介电常数的氧化铪作为栅介质层,由一维碳纳米管搭建的网路状结构作为晶体管导电沟道。实验结果表明,在超柔PI衬底上,所制备柔性场效应晶体管表现出典型的P型导电特性,开关比达到10^(5)以上,具有良好的开关特性。所制备器件在200次弯折之后,仍能表现出10^(4)以上的高开关比,证明所制备柔性晶体管器件具有良好的耐弯折特性,具有应用于可穿戴电子器件的巨大潜力。

Reliability tests and improvements for Sc-contacted n-type carbon nanotube transistors

钪(Sc ) 联系了 n 类型碳 nanotube (CNT ) 有背和最高门的结构的完成地的晶体管(联邦货物税) 被制作了，并且他们在空中的稳定性被调查。氧和水分子可以影响 nanotube 隧道和 Sc/nanotube 接触，这被显示出，导致败坏的接触质量和设备性能。与 n 类型碳 nanotube 联邦货物税的不稳定性联系的这些否定效果能通过使钝化被消除由 atomic-layer-deposition 的薄层的 CNT 设备成年 Al2O3 绝缘体。在钝化以后， n 类型碳 nanotube 联邦货物税被显示甚至在被测试并且暴露了通风超过 146 天，然后光滑得多的输出以后展出优秀空气稳定性特征和减少的门电压从 1 ～ 0.1 V 的磁滞现象被表明什么时候与没有钝化的设备相比。持续电源开著测试也为至少 10 h 在大门应力和在空中当前的高排水管下面在使钝化的 CNT 联邦货物税上被执行，揭示空设备降级有时平的改进性能。这些结果答应那 CNT 设备在空中是可靠的并且可以在实际应用被使用使钝化。