基于非对称掺杂策略的GNRFET电学特性研究

基于量子力学非平衡Green函数理论框架,在开放边界条件下,通过自洽求解三维Poisson和Schrodinger方程,构建了适用于非均匀掺杂的石墨烯场效应管的输运模型.并利用该模型分析计算采用非对称HALO-LDD掺杂策略的石墨烯纳米条带场效应管（GNRFET）的电学特性.通过与采用其他掺杂策略的GNRFET的输出特性、转移特性、开关电流比、亚阈值摆幅、阈值电压漂移等电学特性对比分析,发现这种掺杂结构的石墨烯场效应管具有更大的开关电流比、更低的泄漏电流、更小的亚阈值摆幅和阈值电压漂移,表明采用非对称HALO-LDD掺杂策略的GNRFET具有更好的栅控能力,能够有效的抑制短沟道效应和热载流子效应.     

异质栅碳纳米管场效应管电学特性研究

采用一种量子力学模型,研究了类MOSFET型碳纳米管场效应管(CNTFET)的电流特性.该模型基于二维非平衡格林函数(NEGF)方程和泊松(Poisson)方程自洽全量子数值解.结合器件的工作原理,研究了器件结构尺寸效应,比较分析单栅、异质栅CNTFET的电学特性.研究结果表明,与单橱结构相比,异质栅器件结构具有更低的泄漏电流、更高的电流开关比,并且,在15 nm技术节点以上,异质栅CNTFET器件能够较好地满足ITRS'10的相关性能指标要求.     

石墨烯纳米条带场效应管及构建电路研究

本文提出一种源漏轻掺杂异质栅结构石墨烯纳米条带场效应晶体管Graphene Nano Ribbon Field-effect Transistor(HMG-LDDS-GNR-FET),采用量子力学模型,研究其电学特性.仿真结果表明,与普通石墨烯纳米场效应晶体管(C-GNRFET)相比,HMG-LDDS-GNRFET的漏电流更小、开关电流比更大,电压增益也更大.该研究结果对碳基材料场效应管器件的设计有指导意义.     

石墨烯纳米条带的电子输运性质研究(英文)

采用紧束缚近似模型,运用Green函数和Landauer-Büttiker公式计算了并联型Armchair型边界的石墨烯纳米条带的电子输运性质。结果表明,随着并联纳米条带数量的增加,石墨烯纳米条带电导峰(电导谷)将有相应数量的增加;条带之间的间距增宽,中心区电导谷的宽度将减小。通过数值计算,揭示该新型石墨烯结构电子输运的物理机制,为基于石墨烯的新型器件的设计和优化提供理论指导,并对石墨烯纳米条带在未来集成电路设计中的应用提供理论参考。     

自旋场效应晶体管的电学特性研究(英文)

用非平衡格林函数方法研究一种自旋场效应晶体管的电子输运特性。结果表明,不考虑自旋散射的作用,当漏极电压比较小时该器件能达到很高的磁阻比率。对该器件在考虑自旋散射和不考虑自旋散射下的输出电流进行对比,发现在铁磁平行(反平行)的条件下,考虑自旋散射时的输出电流要比不考虑自旋散射时的输出电流小(大)。研究结果揭示了该器件的物理机制,为该器件的优化设计提供了理论指导。     

采用有限元方法研究轻掺杂源漏结构对异质栅MOSFET的性能影响(英文)

提出了一种轻掺杂源漏结构结合异质材料双栅结构的MOSFET(简称LDDS-HMG-MOSFET)。使用二维非平衡格林函数(NEGF)对该结构进行仿真,其中非平衡格林函数的计算使用有限元法(FEM)。仿真结果表明,在该新型结构中,异质栅结构能够降低漏电流从而能够有效抑制漏极感应势垒较低效应(DIBL),LDDS结构能够增加有效栅长,有效抑制带带隧穿效应(BTBT)和热电子效应。因此,与传统单材料栅结构的MOSFET(简称C-MOSFET)相比,LDDS-HMG-MOSFET具有更加优越的性能、更低的漏电流和更大的开关电流比(Ion/Ioff)。     

锯齿形石墨烯带(7-ZGNR)输运性质的研究

采用基于密度泛函方法的非平衡格林函数,对无限长锯齿形石墨烯带(7-ZGNR)的态密度和输运性质进行了理论计算和模拟。结果表明,此石墨烯带的电子输运系数和其态密度有关,波峰与波谷分别相对应。此外,输运曲线近似在费密能级两边对称。由于宽度只有10nm左右,石墨烯带受量子效应的影响,对不同本征能量的电子的输运系数呈整数变化,相应的电导呈现阶跃式变化,其值均为量子电导G0的整数倍。另外,给石墨烯带加以0~1.5V的偏压,计算I-V曲线。结果发现,此石墨烯带在0~1.5V内的I-V曲线接近于线性,考虑到其带隙值较小,因此可认为7-ZGNR是金属型的锯齿形石墨烯带。采用类似的方法,可以判定其他石墨烯带的输运性质。     

锯齿-扶手椅-锯齿型石墨烯纳米带电子输运特性研究

基于密度泛函理论和非平衡格林函数,研究了中心散射区长度对于锯齿-扶手椅-锯齿型石墨烯纳米带(Z-A-ZGNRs)的电子输运特性的影响.结果表明:中心散射区长度对导电性能有很大的影响.散射区长度较小时,在一定区间内具有明显的负微分电阻现象,长度增加时,这种效应减弱.Z-A-ZGNRs在-2～2 V偏压下存在整流现象,散射...     

石墨烯/光波导集成的非对称场效应结构特性研究

基于微纳加工技术制备了具有非对称场效应结构的石墨烯/光波导集成器件,首次实验测试了交换源漏电极前后器件场效应输运特性差异,并与石墨烯场效应管进行对比分析了引入光波导结构对器件输运特性的影响.由石墨烯场效应器件模型对测试结果进行分析,结果表明交换源漏电极前后器件载流子迁移率分别为787.76和394.67 cm2?V-1...     

异质栅氧化层轻掺杂漏石墨烯纳米条带p-i-n隧穿场效应管量子输运特性的研究

We perform a theoretical study of the effects of the lightly doped drain （LDD） and high-k dielectric on the performances of double gate p-i-n tunneling graphene nanoribbon field effect transistors （TFETs）. The models are based on non-equilibrium Green＇s functions （NEGF） solved self-consistently with 3D-Poisson＇s equations. For the first time, hetero gate dielectric and single LDD TFETs （SL-HTFETs） are proposed and investigated. Simulation results show SL-HTFETs can effectively decrease leakage current, sub-threshold swing, and increase on-off current ratio compared to conventional TFETs and Si-based devices; the SL-HTFETs from the 3p ＋ 1 family have better switching characteristics than those from the 3p family due to smaller effective masses of the former. In addition, comparison of scaled performances between SL-HTFETs and conventional TFETs show that SL-HTFETs have better scaling properties than the conventional TFETs, and thus could be promising devices for logic and ultra-low power applications.     

基于石墨烯纳米条带阵列的光电探测器模型

提出了一种基于石墨烯纳米条带阵列的光电探测器(GNR-PD)结构,讨论了器件的解析模型.基于二维泊松方程,在弱非局域近似条件下建立了GNR-PD的器件模型,推导了其I-V特性和光响应特性.结果表明,GNR-PD具有极高量子效率和光电增益,可以获得高达150 A/W以上的光响应度.     

Performance analysis of charge plasma based dual electrode tunnel FET

This paper proposes the charge plasma based dual electrode doping-less tunnel FET (DEDLTFET). The paper compares the device performance of the conventional doping-less TFET (DLTFET) and doped TFET (DGTFET). DEDLTEFT gives the superior results with high ON state current (I_ON ～ 0.56 mA/μm), I_ON/I_OFF ratio ～ 9.12 × 10¹³ and an average subthreshold swing (AV-SS ～ 48 mV/dec). The variation of different device parameters such as channel length, gate oxide material, gate oxide thickness, silicon thickness, gate work function and temperature variation are done and compared with DLTFET and DGTFET. Through the extensive analysis it is found that DEDLTFET shows the better performance than the other two devices, which gives the indication for an excellent future in low power applications.     

表面粗糙对石墨烯场效应晶体管电流的影响

建立了单栅石墨烯场效应晶体管处于栅氧化层界面平整时的电流模型,在此基础上分析氧化层界面粗糙度对源漏电流的影响．研究表明：粗糙界面会导致源漏电流有所下降;且粗糙度越大,源漏电流下降越多．     

Influence of dummy active patterns on mechanical stress induced by spin-on-glass-filled shallow trench isolation in n-MOSFETs

This paper proposes an electrical method of extracting mechanical stress in n-MOSFETs and analyzes the influence of dummy active patterns on mechanical stress induced by spin-on-glass-filled shallow trench isolation (SOG-filled STI). The proposed method requires only the maximum transconductance g_m,max and measured subthreshold current I_d(sub.), eliminating the effect of deviations of the mobility μ and effective channel length L_eff that occurred in a previous method using μ. In addition, it eliminates the measurement error due to the drain induced barrier lowering (DIBL) effect in a previous method using I_d(sub.). The tensile stress σ_t in the experimental n-MOSFETs was measured as several hundred mega Pascals. An increase of separation distance d between dummy active regions and the Si active region resulted in a decrease of σ_t for d > 0.2 μm. But, σ_t decreased when d decreased from 0.2 to 0.09 μm.     

高性能激光诱导石墨烯压力传感器的研究

为了保证在低成本、易制备的前提下提高激光诱导石墨烯压力传感器的性能,设计了一种石墨烯压力传感器的放大结构。表征了激光诱导石墨烯压力传感器的表面结构,分析了表面多孔泡沫结构对压阻效应的影响,采用COMSOL软件对传感器放大结构的受力情况进行仿真分析,得到在外界压力下石墨烯层的受力情况。选用3D打印方法制备树脂材料放大结构基底,在低成本的同时兼顾了轻质、高精度、高机械强度等性能。测试结果表明,压强在5～20 kPa范围内时,该放大结构的灵敏度较无放大结构提高了约43%。     

Design of GNRFET using different doping profiles near the source and drain contacts

The graphene nanoribbon field effect transistors (GNRFET) suffer from band-to-band tunnelling (BTBT), which in turn causes ambipolar conduction. In this simulation study, we propose a step–linear doping profile for the graphene nanoribbon near the source and drain contacts. This type of doping profile suppresses the BTBT and ambipolar conduction of the transistor. The proposed step–linear dopant distribution efficiently modulates the potential barrier at the source–channel interface, increases the width of the tunnelling region, and thus reduces the OFF-state current by decreasing the possibility of BTBT. A p_z orbital band model with the nearest neighbour is used to simulate the graphene nanoribbon. The Schrödinger equation is solved by non-equilibrium Green's function method to achieve the charge density. In order to calculate the electrostatic potential, the Poisson's equation is solved by means of the non-linear finite difference method. We have used the uncoupled mode space approach significantly to reduce the computational time. It is shown that the proposed doping profile improves the performance of graphene nanoribbon transistor by decreasing the OFF-state current and increasing the ON-state current. We have also observed a slight improvement in the subthreshold slope of the proposed GNRFET. The proposed GNRFET is more suitable than the conventional GNRFETs for switching applications.     

22nm技术节点异质栅MOSFET的特性研究

研究了22 nm栅长的异质栅MOSFET的特性,利用工艺与器件仿真软件Silvaco,模拟了异质栅MOSFET的阈值电压、亚阈值特性、沟道表面电场及表面势等特性,并与传统的同质栅MOSFET进行比较。分析结果表明,由于异质栅MOSFET的栅极由两种不同功函数的材料组成,因而在两种材料界面附近的表面沟道中增加了一个电场峰值,相应地漏端电场比同质栅MOSFET有所降低,所以在提高沟道载流子输运效率的同时也降低了小尺寸器件的热载流子效应。此外,由于该器件靠近源极的区域对于漏压的变化具有屏蔽作用,从而有效抑制了小尺寸器件的沟道长度调制效应,但是由于其亚阈值特性与同质栅MOSFET相比较差,导致漏致势垒降低效应(DIBL)没有明显改善。