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1.
Gate dielectric materials play a key role in device development and study for various applications. We illustrate herein the impact of hetero (high-k/low-k) gate dielectric materials on the ON-current (\(I_{\mathrm{ON}}\)) and OFF-current (\(I_{\mathrm{OFF}}\)) of the heterogate junctionless tunnel field-effect transistor (FET). The heterogate concept enables a wide range of gate materials for device study. This concept is derived from the well-known continuity of the displacement vector at the interface between low- and high-k gate dielectric materials. Application of high-k gate dielectric material improves the internal electric field in the device, resulting in lower tunneling width with high \(I_{\mathrm{ON}}\) and low \(I_{\mathrm{OFF}}\) current. The impact of work function variations and doping on device performance is also comprehensively investigated.  相似文献   

2.
In this paper, we propose and simulate two new structures of electron–hole bilayer tunnel field-effect transistors (EHBTFET). The proposed devices are n-heterogate with \(\hbox {M}_{1}\) as overlap gate, \(\hbox {M}_{2}\) as underlap gate and employs a high-k dielectric pocket in the drain underlap. Proposed structure 1 employs symmetric underlaps (Lgs = Lgd = Lu). The leakage analysis of this structure shows that the lateral ambipolar leakage between channel and drain is reduced by approximately three orders, the OFF-state leakage is reduced by one order, and the \(I_{\mathrm{ON}}/I_{\mathrm{OFF}}\) ratio is increased by more than one order at \(V_\mathrm{{GS}}=V_{\mathrm{DS}} =1.0\) V as compared to the conventional Si EHBTFET. The performance is improved further by employing asymmetric underlaps (\(\hbox {Lgs}\ne \hbox {Lgd}\)) with double dielectric pockets at source and drain, called as proposed structure 2. The pocket dimensions have been optimized, and an average subthreshold swing of 17.7 mV/dec (25.5% improved) over five decades of current is achieved with an ON current of \(0.23~\upmu \hbox {A}/\upmu \hbox {m}\) (11% improved) in proposed structure 2 in comparison with the conventional EHBTFET. Further, the parasitic leakage paths between overlap/underlap interfaces are blocked and the OFF-state leakage is reduced by more than two orders. A high \(I_{\mathrm{ON}}/I_{\mathrm{OFF}}\,\hbox {ratio}~>10^{9}\) (two orders higher) is achieved at \(V_{\mathrm{DS}} =V_{\mathrm{GS}} =1.0~\hbox {V}\) in the proposed structure 2 in comparison with the conventional one.  相似文献   

3.
This paper reports studies of a doping-less tunnel field-effect transistor (TFET) with a \(\hbox {Si}_{0.55} \hbox {Ge}_{0.45}\) source structure aimed at improving the performance of charge-plasma-based doping-less TFETs. The proposed device achieves an improved ON-state current (\(I_{{\mathrm{ON}}} \sim {4.88} \times {10}^{-5}\,{\mathrm{A}}/\upmu {\mathrm{m}}\)), an \(I_\mathrm{ON}/I_\mathrm{OFF}\) ratio of \({6.91} \times {10}^{12}\), an average subthreshold slope (\(\hbox {AV-SS}\)) of \(\sim \) \({64.79}\,{\mathrm{mV/dec}}\), and a point subthreshold slope (SS) of 14.95 mV/dec. This paper compares the analog and radio of frequency (RF) parameters of this device with those of a conventional doping-less TFET (DLTFET), including the transconductance (\(g_{{\mathrm{m}}}\)), transconductance-to-drain-current ratio \((g_\mathrm{m}/I_\mathrm{D})\), output conductance \((g_\mathrm{d})\), intrinsic gain (\(A_{{\mathrm{V}}}\)), early voltage (\(V_{{\mathrm{EA}}}\)), total gate capacitance (\( C_{{\mathrm{gg}}}\)), and unity-gain frequency (\(f_{{\mathrm{T}}}\)). Based on the simulated results, the \(\hbox {Si}_{0.55}\hbox {Ge}_{0.45}\)-source DLTFET is found to offer superior analog as well as RF performance.  相似文献   

4.
In this work, the potential benefit of tri-metal gate engineered nanowire MOSFET with gate stack for analog/RF applications is developed and presented. A systematic, quantitative investigation of main figure of merit for the device is carried out to demonstrate its improved RF/analog performance. The results show an improvement in drain current, \(I_{\mathrm{on}} /I_{\mathrm{off}}\) ratio, transconductance, unity-gain frequency (\(f_{\mathrm{T}}\)), maximum oscillation frequency (\(f_{\mathrm{max}}\)) providing superior RF performance as compared to single and dual-metal gate stack nanowire MOSFET. The suitability of the device for analog/RF applications is also analyzed by implementing the device in a low-noise amplifier circuit, and the S-parameter values are estimated.  相似文献   

5.
A novel high-performance H-shape-gate U-shape-channel junctionless FET (HGUC JL FET) is proposed. Compared with the saddle junctionless FET, the proposed HGUC JL FET shows better subthreshold characteristics and higher on-current. Its electrical properties were extensively investigated by studying the influence of variation of design parameters such as the H-gate thickness, the source/drain extension region height, and the gate oxide thickness and material. Compared with conventional structures, the proposed HGUC JL FET shows better performance, especially on scaling down to several nanometers. The reverse leakage current is also effectively restrained and the \({I}_{\mathrm{on}}\)/\({I}_{\mathrm{off}}\) ratio greatly improved through design optimization.  相似文献   

6.
A two dimensional (2D) analytical drain current model has been developed for a delta-doped tunnel field-effect transistor (D-TFET) that can address the ON-current issues of the conventional TFET. Insertion of a highly doped delta layer in the source region paves the way for improved tunneling volume and thus provides high drain current as compared with TFETs. The present model takes into account the effects of the distance between the delta-doping region and the source–channel interface on the subthreshold swing (SS), current ratio, and ON-current performance. The D-TFET is predicted to have a higher current ratio \(\left( {\frac{I_\mathrm{ON} }{I_\mathrm{OFF} }\cong 10^{11}} \right) \) compared with TFETs \(\left( {\frac{I_\mathrm{ON} }{I_\mathrm{OFF} }\cong 10^{10}} \right) \) with a reasonable SS \(\left( {{\sim }52\,\mathrm{mV/dec}} \right) \) and \(V_\mathrm{th}\) performance at an optimal position of 2 nm from the channel. The surface potential, electric field, and minimum tunneling distance have been derived using the solution of the 2D Poisson equation. The accuracy of the D-TFET model is validated using the technology computer aided design (TCAD) device simulator from Synopsys.  相似文献   

7.
This paper investigates the electrical behavior of the C–V and G–V characteristics of \(\mathrm{Al}/\mathrm{SiO}_{2}/\mathrm{Si}\) structure. The modeling of capacitance and conductance has been developed from complex admittance treatment applied to the proposed equivalent circuit. Poisson transport equations have been used to determine the charge density, surface potential, total capacitance, and flatband and threshold voltages as a function of the gate voltage, frequency (\(\omega )\), and series \(({R}_{\mathrm{s}})\) and parallel \(({R}_{\mathrm{p}})\) resistances. Results showed a frequency dispersion of C–V and G–V curves in both accumulation and inversion regimes. With increasing frequency, the accumulation capacitance is decreased, whereas the conductance is strongly increased. The shape, dispersion, and degradation of C–V and G–V characteristics are more influenced when parallel and series resistances \((\mathrm{R}_{\mathrm{s}}\), \(\mathrm{R}_{\mathrm{p}})\) are dependent to substrate doping density. The variation of \(\mathrm{R}_{\mathrm{s}}\) and \(\mathrm{R}_{\mathrm{p}}\) values led to a reduction of flatband voltage from ?1.40 to ?1.26 V and increase of the threshold voltage negatively from ?0.28 to ?0.74 V. A good agreement has been observed between simulated and measured C–V and G–V curves obtained at high frequency.  相似文献   

8.
In this paper, silicon nanotube field effect transistors (SiNT-FETs) are investigated for independent gate operation using 3D numerical simulation. The parameters, \(\mathrm{I_{ON} , I_{OFF}, V_{T}}\), and the unity gain cut-off frequency \(\mathrm{(f_{T}}\)) are studied in the independent-gate mode. The SiNT-FET we have considered has two gates, namely outer and inner gates, and can be simultaneously driven or independently driven. The physical gate oxide thicknesses of the outer and inner gates of the device are to be converted into effective gate oxide thicknesses due to the non-Euclidean geometry associated with the tube structure. The effective gate oxide thicknesses are different for the same outer and inner physical gate oxide thickness. Since the inner and outer gates are asymmetric, the device parameters extracted at the outer and inner gates are different. Since the independent gate operation allows dynamic threshold voltage adjustment, a model to predict the threshold voltage also known as the threshold voltage sensitivity model is developed for the SiNT device by modifying the double gate FinFET model. These models are verified by TCAD simulation results to validate their accuracy.  相似文献   

9.
We propose herein a new dual-gate metal–oxide–semiconductor field-effect transistor (MOSFET) with just a unipolar junction (UJ-DG MOSFET) on the source side. The UJ-DG MOSFET structure is constructed from an \({N}^{+}\) region on the source side with the rest consisting of a \({P}^{-}\) region over the gate and drain, forming an auxiliary gate over the drain region with appropriate length and work function (named A-gate), converting the drain to an \({N}^{+}\) region. The new structure behaves as a MOSFET, exhibiting better efficiency than the conventional double-gate MOSFET (C-DG MOSFET) thanks to the modified electric field. The amended electric field offers advantages including improved electrical characteristics, reliability, leakage current, \({I}_{\mathrm{ON}}/I_{\mathrm{OFF}}\) ratio, gate-induced drain leakage, and electron temperature. Two-dimensional analytical models of the surface potential and electric field over the channel and drain are applied to investigate the drain current in the UJ-DG MOSFET. To confirm their accuracy, the MOSFET characteristics obtained using the 2D Atlas simulator for the UJ-DG and C-DG are analyzed and compared.  相似文献   

10.
Transition metal (TM) electrodes based dopingless zero sub-threshold slope and zero impact ionization FET (DL-Z\(^{2}\)FET) is reported in this paper. The work-function engineering of TM electrodes is used for charge plasma based electrostatic pseudo doping. Work-function difference between TM electrodes and the undoped silicon film induces p\(^{+}\) and n\(^{+}\) regions in the film. TMs exhibit easy tunability of work-function and their CMOS fabrication compatibility pledges for their potential applications as these electrodes. A technology computer-aided design simulation study is performed to provide physical insight into its working mechanism and performance. It exhibits all the inherent characteristics of conventional Z\(^{2}\)FET, viz. zero slope switching, high \(I_{ON}/I_{OFF}\) ratio, lower operating voltages, immunity towards hot electron degradation and gate controlled hysteresis. The detrimental doping control issues, mobility degradation due to heavy doping and statistical random dopant fluctuations can no more obviate the device performance, it results in more process variations immune design. Hence it can be a potential fast switching transistor.  相似文献   

11.
This paper shows the potential benefits of using the trigate junctionless transistor (JLT) with dual-k sidewall spacers to enhance analog/radio-frequency (RF) performance at 20-nm gate length. Simulation study shows that the source-side-only dual-k spacer (dual-kS) JLT can improve all analog/RF figures of merit (FOMs) compared with the conventional JLT structure. The dual-kS JLT shows improvement in intrinsic voltage gain (\(A_{V0}\)) by \(\sim \)44.58 %, unity-gain cutoff frequency (\(f_\mathrm{T}\)) by \(\sim \)7.67 %, and maximum oscillation frequency (\(f_\mathrm{MAX}\)) by \(\sim \)6.4 % at drain current \((I_\mathrm{ds}) = 10\,\upmu \hbox {A}/\upmu \hbox {m}\) compared with the conventional JLT structure. To justify the improvement in all analog/RF FOMs, it is also found that the dual-kS structure shows high electron velocity near the source region because of the presence of an additional electric field peak near the source region, resulting in increased electron transport efficiency and hence improved transconductance (\(g_\mathrm{m}\)). Furthermore, the dual-kS JLT shows a reduction in the electric field value near the drain end, thereby improving short-channel effects.  相似文献   

12.
In this paper, we propose a double aperture double-gate AlGaN/GaN vertical high-electron-mobility transistor (HEMT) to improve the device characteristics, such as the current and the ON resistance (\(\hbox {\textit{R}}_{\mathrm{ON}}\)). The proposed vertical HEMT results are compared to the conventional single aperture single-gate vertical HEMT of equal dimensions, and increased drain current and lower \(\hbox {\textit{R}}_{\mathrm{ON}}\) are shown. A comprehensive simulation study has also been carried out for the proposed device, to analyse the impact of thickness and doping concentration of aperture, drift region, and current blocking layer. In addition, the effect of different materials in current blocking layer on device characteristics is also studied. The obtained results and their effect on device characteristics have been thoroughly analysed and explained accordingly.  相似文献   

13.
An ultra-low specific on-resistance \((R_\mathrm{{on,sp}})\) trench SOI LDMOS with a floating vertical field plate structure (FVFPT SOI) is proposed in this paper. A floating vertical plate (FVFP) is introduced into the filled oxide trench of a conventional trench SOI LDMOS (CT SOI) to improve its electrical performance. We conduct related performance analysis to this device by simulation and investigate the effects of different parameters on its performance. The FVFP causes an assisted depletion effect especially for the trench surface regions. An ultra-low \(R_\mathrm{{on,sp}}\) is therefore obtained in the FVFP device due to higher drift region doping concentration \((N_\mathrm{{d}})\). A breakdown voltage (BV) of 188V and a \(R_\mathrm{{on,sp}}\) of \(0.9 \hbox { m}\Omega \, \hbox { cm}^{2}\) are realized on a 4.8-\({\upmu }\hbox {m}\)-long drift region, a 7.5-\({\upmu }\hbox {m}\)-thick top-silicon layer and a 0.5-\({\upmu }\hbox {m}\)-thick buried oxide (BOX) layer by our simulation. Eventually, the \(R_\mathrm{{on,sp}}\) for the FVFPT SOI can be reduced by more than 60%, while its BV is maintained the same class as the CT SOI, and the figure of merit (FOM) is enhanced by 155%. And a set of optimal parameters, including the structure parameters of plate and the property parameters of device, are obtained.  相似文献   

14.
In this paper, we aim to explore the potential benefits of using source side only dual-k spacer (Dual-kS) trigate FinFET structure to improve the analog/RF figure of merit (FOM) for low power operation at 20 nm gate length. It has been observed from the results that Dual-kS (inner spacer high-k) FinFET structure improves the coupling of the gate fringe field to the underlap region towards the source side and results into improvement in transconductance \((g_{m})\) and output conductance \((g_{ds})\). It was also found that drain side only dual-k spacer (Dual-kD) improves the coupling of the gate fringe field to the underlap region towards the drain side which helps to shift away the drain field from gate edge and results into improvement in output conductance \((g_{ds})\) only at the cost of increase in Miller capacitance. A comparative simulation study has been performed on four different device structures namely both side low-k spacers (conventional), both side dual-k spacer (Dual-kB), Dual-kD and Dual-kS structures. From the simulation study, it was found that that Dual-kS structure has potential to improve \(g_{m}\) by \(\sim \)8.7 %, \(g_{ds}\) by \(\sim \)32.24 %, intrinsic gain \((A_{V0})\) by \(\sim \)11.44 %, early voltage \((V_{EA})\) by \(\sim \)47.59 %, maximum oscillation frequency (\(f_{MAX}\)) by \(\sim \)1.7 % and the ratio of gate-source capacitance and gate-drain capacitance \((C_{gs}/C_{gd})\) by \(\sim \)15.27 % with a slight reduction in the value of unity gain cut-off frequency (\(f_{T}\)) by \(\sim \)0.58 % in comparison to the conventional structure at drain current \((I_{ds})\) of \(10\,\upmu \)A/\(\upmu \)m. Furthermore, to reduce the drain field influence on the channel region, we also studied the effect of asymmetric drain extension length on Dual-kS FinFET structure.  相似文献   

15.
In this paper, the RF and DC behaviours of a SiN-passivated 20-nm gate length metamorphic high electron mobility transistor (MHEMT) on GaAs substrate with \({\updelta }\)-doped sheets on either side of the composite channel are studied using the Synopsys TCAD tool. The 20-nm enhancement-mode MHEMT with \({\updelta }\)-doped sheets on either side of the \(\hbox {In}_{0.75}\hbox {Ga}_{0.25}\hbox {As}\)/InAs/ \(\hbox {In}_{0.75}\hbox {Ga}_{0.25}\hbox {As}\) multilayer channel shows a transconductance of 3000 mS/mm, cut-off frequency (\({f}_{\mathrm{T}}\)) of 760 GHz and a maximum-oscillation frequency (\({f}_{\mathrm{max}}\)) of 1270 GHz. The threshold voltage of the device is found to be 0.07 V. The room-temperature Hall mobilities of the two-dimensional sheet charge density (2DEG) are measured to be over \(12800\,\hbox {cm}^{2}\)/Vs with a sheet charge density larger than 4 \(\times \) \(10^{12}\,\hbox {cm}^{-2}\). These high-performance enhancement-mode MHEMTs are attractive candidates for future terahertz applications such as high-resolution radars for space research and also for low-noise wide-bandwidth amplifier for future communication systems.  相似文献   

16.
Here, we develop a 3D analytical model for potential in a lightly doped dual-material-gate FinFET in the subthreshold region. The model is based on the perimeter-weighted sum of a dual-material double-gate (DMDG) asymmetric MOSFET and a DMDG symmetric MOSFET. The potential model is used to determine the minimum surface potential needed to obtain the threshold voltage \((V_{\mathrm{T}})\) and subthreshold swing (SS) by considering the source barrier changes in the leakiest channel path. The proposed model is capable of reducing the drain-induced barrier lowering (DIBL) as well as the hot carrier effects offered by this device. The impact of control gate ratio and work function difference between the two metal gates on \(V_{\mathrm{T}}\) and SS are also correctly established by the model. All model derivations are validated by comparing the results with technology computer-aided design (TCAD) simulation data.  相似文献   

17.
A new analytical model for the gate threshold voltage (\(V_\mathrm{TG}\)) of a dual-material double-gate (DMDG) tunnel field-effect transistor (TFET) is reported. The model is derived by solving the quasi-two-dimensional Poisson’s equation in the lightly doped Si film and employing the physical definition of \(V_\mathrm{TG}\). A numerical simulation study of the transfer characteristics and \(V_\mathrm{TG}\) of a DMDG TFET has been carried out to verify the proposed analytical model. In the numerical calculations, extraction of \(V_\mathrm{TG}\) is performed based on the transconductance change method as already used for conventional metal–oxide–semiconductor FETs (MOSFETs). The effects of gate length scaling, Si film thickness scaling, and modification of the gate dielectric on \(V_\mathrm{TG}\) are reported. The dependence of \(V_\mathrm{TG}\) on the applied drain bias is investigated using the proposed model. The proposed model can predict the effect of variation of all these parameters with reasonable accuracy.  相似文献   

18.
In this paper, we have proposed a device and named it dual electrode doping-less TFET (DEDLTFET), in which electrodes on top and bottom of source and drain are considered to enhance the ON state current and Analog performances. The charge plasma technique is used to generate electron’s and hole’s clouding depending upon their respective work functions at top and bottom of source/drain electrode. Band-to-band-tunneling rate is similar on both sides of source-channel junctions, which increases ON state current. The analog performance parameters of DEDLTFET are investigated and using device simulation the demonstrated characteristics are compared with doping-less (DLTFET) and the conventional doped double gate TFET (DGTFET), such as transconductance \((\hbox {g}_\mathrm{m})\), transconductance to drain current ratio \((\hbox {g}_\mathrm{m}/\hbox {I}_\mathrm{D})\), output-conductance (g\(_{d})\), output resistance \((\hbox {r}_\mathrm{d})\), early voltage \((\hbox {V}_\mathrm{EA})\), intrinsic gain \((\hbox {A}_\mathrm{V})\), total gate capacitance \((\hbox {C}_\mathrm{gg})\) and unity gain frequency \((\hbox {f}_\mathrm{T})\). From the simulation results, it is observed that DEDLTFET has significantly improved analog performance as compared to DGTFET and DLTFET.  相似文献   

19.
In this paper, a graded channel doping paradigm is proposed to improve the nanoscale double gate junctionless DGJL MOSFET electrical performance. A careful mechanism study based on numerical investigation and a performance comparison between the proposed and conventional design is carried out. The device figures-of-merit, governing the switching and leakage current behavior are investigated in order to reveal the transistor electrical performance for ultra-low power consumption. It is found that the channel doping engineering feature has a profound implication in enhancing the device electrical performance. Moreover, the impact of the high-k gate dielectric on the device leakage performance is also analyzed. The results show that the proposed design with gate stacking demonstrates superior \(I_{{\textit{ON}}}/I_{{\textit{OFF}}}\) ratio and lower leakage current as compared to the conventional counterpart. Our analysis highlights the good ability of the proposed design including a high-k gate dielectric for the reduction of the leakage current. These characteristics underline the distinctive electrical behavior of the proposed design and also suggest the possibility for bridging the gap between the high derived current capability and low leakage power. This makes the proposed GCD-DGJL MOSFET with gate stacking a potential alternative for high performance and ultra-low power consumption applications.  相似文献   

20.

Objective

Diffusion-weighted magnetic resonance imaging (DW-MRI) combined with intravoxel incoherent motion (IVIM) analysis may be applied for assessment of organ lesions, diffuse parenchymal pathologies, and therapy monitoring. The aim of this study was to determine IVIM reference parameters of abdominal organs for translational research in a large cohort of C57Bl/6 laboratory mice.

Materials and methods

Anesthetized mice (n = 29) were measured in a 4.7 T small-animal MR scanner with a diffusion-weighted echo-planar imaging sequence at the \(b\)-values 0, 13, 24, 55, 107, 260, 514, 767, 1020 s/mm2. IVIM analysis was conducted on the liver, spleen, renal medulla and cortex, pancreas, and small bowel with computation of the true tissue diffusion coefficient \(D_{\text{t}}\), the perfusion fraction \(f_{\text{p}}\), and the pseudodiffusion coefficient \(D_{\text{p}}\). Microvessel density (MVD) was assessed by immunohistochemistry (IHC) against panendothelial cell antigen CD31.

Results

Mean values of the different organs [\(D_{\text{t}}\) (10?3 mm2/s); \(f_{\text{p}}\) (%); \(D_{\text{p}}\) (10?3 mm2/s); MVD (MV/mm2)]: liver 1.15 ± 0.14; 14.77 ± 6.15; 50.28 ± 33.21, 2008.48 ± 419.43, spleen 0.55 ± 0.12; 9.89 ± 5.69; 24.46 ± 17.31; n.d., renal medulla 1.50 ± 0.20; 14.63 ± 4.07; 35.50 ± 18.01; 1231.88 ± 290.61, renal cortex 1.34 ± 0.18; 10.83 ± 3.70; 16.74 ± 6.74; 810.09 ± 193.50, pancreas 1.23 ± 0.22; 20.12 ± 7.46; 29.35 ± 17.82, 591.15 ± 86.25 and small bowel 1.06 ± 0.13; 16.48 ± 3.63; 15.31 ± 7.00; 420.50 ± 168.42. Unlike \(D_{\text{t}}\) and \(f_{\text{p}}\), \(D_{\text{p}}\) correlates significantly with MVD (r = 0.90, p = 0.037).

Conclusion

This systematic evaluation of murine abdominal organs with IVIM and MVD analysis allowed to establish reference parameters for future DW-MRI translational research studies on small-animal disease models.
  相似文献   

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