Analytical Model Of Subthreshold Swing Research Articles

Analytical subthreshold swing model of junctionless elliptic gate-all-around (GAA) FET

<abstract> <p>An analytical subthreshold swing (SS) model has been presented to determine the SS of an elliptic junctionless gate-all-around field-effect transistor (GAA FET). The analysis of a GAA FET with an elliptic cross-section is essential because it is difficult to manufacture a GAA FET with an accurate circular cross-section during the process. The SS values obtained using the proposed SS model were compared with 2D simulation values and other papers to confirm good agreement. Using this analytical SS model, SS was analyzed according to the eccentricity of the elliptic cross-section structure. As a result, it was found that the carrier control ability within the channel improved as the eccentricity increased due to a decrease in the effective channel radius by a decrease in the minor axis length and a decrease in the minimum potential distribution within the channel, and thus the SS decreased. There was no significant change in SS until the eccentricity increased to 0.75 corresponding to the aspect ratio (AR), the ratio of the minor and major axis lengths, of 1.5. However, SS significantly decreased when the eccentricity increased to 0.87 corresponding to AR = 2. As a result of the SS analysis for changes in the device parameters of the GAA FET, changes in the channel length, radius, and oxide film thickness significantly affected the changing rate of SS with eccentricity.</p> </abstract>

Analytical Model of Subthreshold Swing for Junctionless Double Gate MOSFET Using Ferroelectric Negative Capacitance Effect

An analytical Subthreshold Swing (SS) model is presented to observe the change in the SS when a stacked SiO2-metal-ferroelectric structure is used as the oxide film of a JunctionLess Double Gate (JLDG) MOSFET. The SS of 60 mV/dec or less is essential to reduce power dissipation while maintaining transistor performance. If a ferroelectric material with Negative Capacitance (NC) effect is used, the SS can be reduced below 60 mV/dec. The analytical SS model of the ferroelectric NC FET presented to analyze this was in good agreement with the SS derived from the relation between the drain current and gate voltage, using 2D potential distribution. As results were derived from the analytical SS model, it was found that it is possible to obtain an SS of 60 mV/dec or less even at 15 nm channel length by adjusting the thicknesses of the silicon channel, SiO2, and ferroelectric. In particular, the change in SS according to the ferroelectric thickness was saturated as the thickness of SiO2 increased and was almost constant as the thickness of the silicon channel decreased. ABSTRAK: Model Ayunan Subambang (SS) analitikal dibentangkan bagi melihat perubahan pada SS apabila struktur feroelektrik-logam-SiO2 bertindan digunakan sebagai filem oksida bagi MOSFET Dua Get Tanpa Simpang (JLDG). SS 60 mV/dec atau kurang adalah penting bagi mengurangkan pelesapan kuasa sambil mengekalkan prestasi transistor. Jika bahan feroelektrik dengan kesan Kapasitans Negatif (NC) digunakan, SS dapat dikurangkan bawah 60 mV/dek. Model SS analitikal feroelektrik NC FET yang digunakan bagi kajian ini adalah sesuai dengan SS yang diperoleh daripada hubungan antara arus serapan dan voltan get, menggunakan edaran potensi 2D. Dapatan terbitan melalui model SS analitikal, mendapati bahawa adalah mungkin bagi mendapatkan SS pada 60 mV/dek atau kurang walaupun panjang laluan adalah 15 nm dengan melaraskan ketebalan saluran silikon, SiO2, dan feroelektrik. Terutama apabila perubahan ketebalan feroelektrik SS adalah tepu ketika ketebalan SiO2 meningkat, dan hampir malar apabila ketebalan saluran silikon berkurang.

Analytical model of subthreshold swing in junctionless gate-all-around (GAA) FET with ferroelectric

<abstract><p>An analytical SS model is presented to observe the subthreshold swing (SS) of a junctionless gate-all-around (GAA) FET with ferroelectric in this paper. For the gate structure, a multilayer structure of metal-ferroelectric-metal-insulator-semiconductor (MFMIS) was used, and the SS was calculated in $15 \leqslant {P_r} \leqslant 30\,\mu C/c{m^2}$ and $0.8 \leqslant {E_c} \leqslant 1.5\,MV/cm$, which are the ranges of remanent polarization and coercive field suggested in various experiments in the case of HZO as the ferroelectric material. It was found that the SSs from the presented analytical SS model agree well with those derived from the relationship between drain current and gate voltage using a 2D potential distribution in the range of device parameters used for simulation. As a result of analyzing the SS of the junctionless GAA FET with ferroelectric using the analytical SS model presented in this paper, the SS decreased because the voltage across the inner gate decreased when the ferroelectric thickness increased. It was observed that the condition of SS < 60 mV/dec was sufficiently obtained according to changes in device parameters such as channel length, channel radius and ferroelectric thickness, and that the SS maintained a constant value according to the ratio of remanent polarization and coercive field <italic>P</italic><sub><italic>r</italic></sub>/<italic>E</italic><sub><italic>c</italic></sub>. As <italic>P</italic><sub><italic>r</italic></sub>/<italic>E</italic><sub><italic>c</italic></sub> increases, the SS increases as the ferroelectric capacitance increases. As the channel length becomes smaller, the change in SS according to <italic>P</italic><sub><italic>r</italic></sub>/<italic>E</italic><sub><italic>c</italic></sub> is more severe.</p></abstract>

Analysis of Subthreshold Swing of Symmetric Junctionless Double Gate MOSFET Using Gaussian Doping Profile

—The variation of subthreshold swing(SS) according to the projected range (Rp ) and standard projected deviation (σp ) was analyzed when the symmetrical junctionless double gate (JLDG) MOSFET was doped with Gaussian doping profile. For this purpose, the analytical SS model was presented. We compared with the TCAD results to turn out the validity of this model, and the SSs of this model agreed with those of TCAD. The effective conduction path and mean doping concentration affecting the SS were analyzed according to the Rp and σp . As a result, the SS increased as the Rp and σp increased simultaneously. The smaller the Rp and the larger the σp , the lower the SS. When Rp = 1.5 nm, it showed the SS below 100mV/dec without being affected by the change of σp or silicon thickness. When σp = 3nm, it was also 100mV/dec or less regardless of the change of Rp and silicon thickness. Keywords— Double gate, Junctionless, Subthreshold swing, Gaussian, Projected range, Standard projected deviation

An Analytical Subthreshold Swing Model for fully-depleted MOSFETs with vertical Gaussian profile fabricated on modified silicon-on-insulator wafers

The objective of this study is to present an analytical subthreshold swing model for fully-depleted metal-oxide semiconductor field-effect transistors (MOSFETs) with vertical Gaussian profile fabricated on modified Silicon-on-Insulator (SOI) wafers. Commercial SOI wafers are radiation hardened by Si+ implantation which creates interface traps at buried SiO2/Si interface. Considering that channel potential is affected by non-uniform doping profile combined with process- and radiation-induced traps, the model is derived based on effective conduction path effect. The proposed model is validated by comparing analytical results with numerical simulation data obtained by using commercially available Sentaurus technology computer-aided design. The model agrees well with experimental extractions of irradiated nMOSFETs. This model is believed to be able to provide better physical insight and understanding of total dose irradiated modified SOI MOSFET devices operating in subthreshold regime.

Analytical model of subthreshold swing of a gate and channel engineered double gate MOSFET

AbstractWe have developed a 2‐dimensional analytical model to study the subthreshold swing and channel conductance of a gate and channel engineered double gate MOSFET. Basic diffusion equation has been considered to model the drain to source current of the device in subthreshold region and expressions of the device parameters like subthreshold swing and channel conductance have been derived. Subthreshold swing variations of the device with varied materials, channel, and effective oxide layer thickness and channel length have also been investigated. Changes in subthreshold swing owing to different doping profile concentrations have been explored. Effect of similar device parameters on the channel conductance of the device has been examined as well. Another important observation of the work is the pseudo flat band condition of the device structure based on the intersecting point of body potentials of the device at different thickness of the channel. The analytical results of the proposed model have been validated with the numerical results from commercially available 2‐dimensional device simulator.

Analytical modeling of subthreshold swing in undoped trigate SOI MOSFETs

A new analytical model for the subthreshold swing of nanoscale undoped trigate silicon-on-insulator metal---oxide---semiconductor field-effect transistors (MOSFETs) is proposed, based on the channel potential distribution and physical conduction path concept. An analytical model for the potential distribution is obtained by solving the three-dimensional (3-D) Poisson's equation, assuming a parabolic potential distribution between the lateral gates. In addition, mobile charges are considered in the model. The proposed analytical model is investigated and compared with results obtained from 3-D simulations using the ATLAS device simulator and experimental data. It is demonstrated that the analytical model predicts the subthreshold swing with good accuracy for different lengthes, thicknesses, and widths of channel.

A Subthreshold Swing Model for Symmetric Double-Gate (DG) MOSFETs with Vertical Gaussian Doping

An analytical subthreshold swing model is presented for symmetric double-gate (DG) MOSFETs with Gaussian doping profile in vertical direction. The model is based on the effective conduction path effect (ECPE) concept of uniformly doped symmetric DG MOSFETs. The effect of channel doping on the subthreshold swing characteristics for non-uniformly doped device has been investigated. The model also includes the effect of various device parameters on the subthreshold swing characteristics of DG MOSFETs. The proposed model has been validated by comparing the analytical results with numerical simulation data obtained by using the commercially available ATLAS™ device simulator. The model is believed to provide a better physical insight and understanding of DG MOSFET devices operating in the subthreshold regime.