Influence of Channel Length and High-K Oxide Thickness on Subthreshold DC Performance of Graded Channel and Gate Stack DG-MOSFETs

NANO ◽  
2016 ◽  
Vol 11 (09) ◽  
pp. 1650101 ◽  
Author(s):  
Sarosij Adak ◽  
Sanjit Kumar Swain ◽  
Arka Dutta ◽  
Hafizur Rahaman ◽  
Chandan Kumar Sarkar

Comparative assessment of graded channel gate stack (GCGS) DG MOSFET structure is done by using two-dimensional (2D) Sentrausu TCAD simulator for different high K oxide thickness. This novel device includes gate stack (GS) engineering (high K) and nonuniformly channel engineering (GC) to suppress the short channel effects and improve the device performance. This novel device can be a better alternative for the future high speed switching and low power circuit applications. It has the advantage of improved breakdown voltage, reduced leakage current, low output conductance and reduced bipolar parasitic effects. The given device must be properly investigated with respect to the variation of different high K oxide thickness on different parameters such as drain induced barrier lowering (DIBL), subthreshold slope (SS), [Formula: see text]/[Formula: see text], [Formula: see text] roll off before fabrication to have better reliability. The 2D Sentrausu TCAD simulator using drift-diffusion model was used to simulate the developed structure and good agreement is obtained with respect to already published result in the sub-threshold regime. The result indicates that there is a need to be optimize the DC parameters for specific circuit applications.

2017 ◽  
Vol 2 (2) ◽  
pp. 15-19 ◽  
Author(s):  
Md. Saud Al Faisal ◽  
Md. Rokib Hasan ◽  
Marwan Hossain ◽  
Mohammad Saiful Islam

GaN-based double gate metal-oxide semiconductor field-effect transistors (DG-MOSFETs) in sub-10 nm regime have been designed for the next generation logic applications. To rigorously evaluate the device performance, non-equilibrium Green’s function formalism are performed using SILVACO ATLAS. The device is turn on at gate voltage, VGS =1 V while it is going to off at VGS = 0 V. The ON-state and OFF-state drain currents are found as 12 mA/μm and ~10-8 A/μm, respectively at the drain voltage, VDS = 0.75 V. The sub-threshold slope (SS) and drain induced barrier lowering (DIBL) are ~69 mV/decade and ~43 mV/V, which are very compatible with the CMOS technology. To improve the figure of merits of the proposed device, source to gate (S-G) and gate to drain (G-D) distances are varied which is mentioned as underlap. The lengths are maintained equal for both sides of the gate. The SS and DIBL are decreased with increasing the underlap length (LUN). Though the source to drain resistance is increased for enhancing the channel length, the underlap architectures exhibit better performance due to reduced capacitive coupling between the contacts (S-G and G-D) which minimize the short channel effects. Therefore, the proposed GaN-based DG-MOSFETs as one of the excellent promising candidates to substitute currently used MOSFETs for future high speed applications.


VLSI Design ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-5
Author(s):  
Sotoudeh Hamedi-Hagh ◽  
Ahmet Bindal

Vertical nanowire surrounding gate field effect transistors (SGFETs) provide full gate control over the channel to eliminate short-channel effects. This paper presents design and characterization of a differential pair amplifier using NMOS and PMOS SGFETs with a 10 nm channel length and a 2 nm channel radius. The amplifier dissipates 5 μW power and provides 5 THz bandwidth with a voltage gain of 16, a linear output voltage swing of 0.5 V, and a distortion better than 3% from a 1.8 V power supply and a 20 aF capacitive load. The 2nd- and 3rd-order harmonic distortions of the amplifier are −40 dBm and −52 dBm, respectively, and the 3rd-order intermodulation is −24 dBm for a two-tone input signal with 10 mV amplitude and 10 GHz frequency spacing. All these parameters indicate that vertical nanowire surrounding gate transistors are promising candidates for the next generation high-speed analog and VLSI technologies.


Author(s):  
Hakkee Jung

Threshold voltage roll-off is analyzed for sub-10 nm asymmetric double gate (DG) MOSFET. Even asymmetric DGMOSFET will increase threshold voltage roll-off in sub-10 nm channel length because of short channel effects due to the increase of tunneling current, and this is an obstacle against the miniaturization of asymmetric DGMOSFET. Since asymmetric DGMOSFET can be produced differently in top and bottom oxide thickness, top and bottom oxide thicknesses will affect the threshold voltage roll-off. To analyze this, <em>thermal</em><em> </em>emission current and tunneling current have been calculated, and threshold voltage roll-off by the reduction of channel length has been analyzed by using channel thickness and top/bottom oxide thickness as parameters. As a result, it is found that, in short channel asymmetric double gate MOSFET, threshold voltage roll-off is changed greatly according to top/bottom gate oxide thickness, and that threshold voltage roll-off is more influenced by silicon thickness. In addition, it is found that top and bottom oxide thickness have a relation of inverse proportion mutually for maintaining identical threshold voltage. Therefore, it is possible to reduce the leakage current of the top gate related with threshold voltage by increasing the thickness of the top gate oxide while maintaining the same threshold voltage.


2002 ◽  
Vol 716 ◽  
Author(s):  
Krishna Kumar Bhuwalka ◽  
Nihar R. Mohapatra ◽  
Siva G. Narendra ◽  
V Ramgopal Rao

AbstractIt has been shown recently that the short channel performance worsens for high-K dielectric MOSFETs as the physical thickness to the channel length ratio increases, even when the effective oxide thickness (EOT) is kept identical to that of SiO2. In this work we have systematically evaluated the effective dielectric thickness for different Kgate to achieve targeted threshold voltage (Vt), drain-induced barrier lowering (DIBL) and Ion/Ioff ratio for different technology generations down to 50 nm using 2-Dimensional process and device simulations. Our results clearly show that the oxide thickness scaling for high-K gate dielectrics and SiO2 follow different trends and the fringing field effects must be taken into account for estimation of effective dielectric thickness when SiO2 is replaced by a high-K dielectric.


2017 ◽  
Vol 31 (01) ◽  
pp. 1650242 ◽  
Author(s):  
Behrooz Abdi Tahne ◽  
Ali Naderi

In this paper, a new structure, step–linear doping MOSCNT (SLD-MOSCNT), is proposed to improve the performance of basic MOSCNTs. The basic structure suffers from band to band tunneling (BTBT). We show that using SLD profile for source and drain regions increases the horizontal distance between valence and conduction bands at gate to source/drain junction which reduces BTBT probability. SLD performance is compared with other similar structures which have recently been proposed to reduce BTBT such as MOSCNT with lightly-doped drain and source (LDDS), and with double-light doping in source and drain regions (DLD). The obtained results using a nonequilibrium Green’s function (NEGF) method show that the SLD-MOSCNT has the lowest leakage current, power consumption and delay time, and the highest current ratio and voltage gain. The ambipolar conduction in the proposed structure is very low and can be neglected. In addition, these structures can improve short-channel effects. Also, the investigation of cutoff frequency of the different structures shows that the SLD has the highest cutoff frequency. Device performance has been investigated for gate length from 8 to 20 nm which demonstrates all discussions regarding the superiority of the proposed structure are also valid for different channel lengths. This improvement is more significant especially for channel length less than 12 nm. Therefore, the SLD can be considered as a candidate to be used in the applications with high speed and low power consumption.


2016 ◽  
Vol 61 ◽  
pp. 24-29 ◽  
Author(s):  
Sanjit Kumar Swain ◽  
Arka Dutta ◽  
Sarosij Adak ◽  
Sudhansu Kumar Pati ◽  
Chandan Kumar Sarkar

2002 ◽  
Vol 716 ◽  
Author(s):  
Abhisek Dixit ◽  
Rajiv O. Dusane ◽  
V. Ramgopal Rao

AbstractDegrading of short-channel effects (SCE) e.g. Drain-Induced-Barrier-Lowering (DIBL), charge-sharing etc., as CMOS devices are scaled into the sub-50nm regime, is a major roadblock for ULSI technologies. This problem can be circumvented to some extent by a proper scaling of MOSFET vertical dimensions (junction depths, oxide thickness etc.). In this work we propose a novel implementation of an electrically induced junction (EJ) MOSFET. An EJ-MOSFET is different from conventional CMOS device in that the gate voltage electrically induces the shallow source-drain extensions (SDEs). In such a device the SDEs are underneath the gate and contain low-doped regions of opposite conductivity as that of deep source-drain (S/D). In order to turn ON the device, a voltage is applied at the gate of EJ-MOSFET device, such that these low doped regions below poly-Si gate get inverted and serve as SDEs. Consequently, the effective channel length in this condition is the distance between these low-doped regions. On the contrary, at any gate voltage less than that required for inverting these regions, no SDEs are induced, and the effective channel length is equal to the physical separation between the deep S/D junctions.


NANO ◽  
2019 ◽  
Vol 14 (05) ◽  
pp. 1950060 ◽  
Author(s):  
Sarosij Adak ◽  
Sanjit Kumar Swain

This work systematically investigated the effect of high-[Formula: see text] oxide materials on the performance of InAlN/GaN heterostructure underlap double gate (DG) MOS-HEMTs by considering 2D Sentaurus TCAD simulation. During the course of simulation, hydrodynamic mobility model was implemented and the obtained results were used for validating the model with the previously published experimental results. Different device performance parameters are thoroughly studied for different high-[Formula: see text] oxide materials by performing extensive simulations. It is verified that short channel effects (SCEs), key analog and RF figures of merits parameters and [Formula: see text]th improved with an increase in the value of high-[Formula: see text] oxide material. Moreover, it is also revealed that there is a significant growth in the values of key analog and RF figures of merits with respect to high-[Formula: see text] values. This analysis suggested that use of a suitable value of high-[Formula: see text]-valued oxide material in InAlN/GaN heterostructure underlap DG MOS-HEMTs can be one of the alternatives for future high speed and microwave applications.


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