This paper proposes an analytical 2-D model for the channel potential and threshold voltage of double-gate junctionless FETs with a vertical Gaussian-like doping profile. The 2-D Poisson equation has been solved by using the evanescent-mode analysis to obtain the potential distribution function in the channel. The position of the conduction path also has been modeled to calculate the potential at different positions of the conduction path. The validity of the proposed 2-D potential and threshold voltage models is shown by comparing the results with the simulation data obtained by a 2-D TCAD ATLAS device simulator.

Analytical Modeling of Channel Potential and Threshold Voltage of Double-Gate Junctionless FETs With a Vertical Gaussian-Like Doping Profile

A new signal processing method, which uses a modified chirp signal for air-coupled ultrasonic imaging, is described. A combination of the elliptical and Tukey window functions has been shown to give a better performance than the Hanning windowing used in most pulse- compression algorithms for air-coupled applications. The elliptical-Tukey chirp signal provides an improvement in both the resolution of images and signal-to-noise ratios. In addition, this type of signal also reduces the level of signal voltages required to drive the source transducer while maintaining the performance of the system. This approach, thus, may have wide interest in all forms of wide bandwidth ultrasonic imaging.

Elliptical-Tukey Chirp Signal for High-Resolution, Air-Coupled Ultrasonic Imaging

A two-dimensional analytical model for the threshold voltage of a short-channel MOSFET with a Gaussian-doped channel has been developed. The Gaussian profile has been simulated by a novel integrable function. This makes possible a purely analytical solution of the two-dimensional Poissons equation in the channel region of the MOSFET. >

A two-dimensional analytical model of threshold voltages of short-channel MOSFETs with Gaussian-doped channels

Window functions have been successfully used in various areas of signal processing and communication. The role of windows is quite impressive and economical from the point of view of computational complexity and ease associated with its application. A brief description of the window functions along with their common properties and parameters is presented in this paper. A classification of all the available window functions is made and they are incorporated accordingly in a tabular manner along with their mathematical expressions (in continuous and discrete time domain) and diagrams.

WINDOWS: A Tool in Signal Processing

Simple analytical expressions involving Bessel functions are obtained for various window functions. Some of the windows take the form of Kaiser-Bessel and Dolph-Chebyshev functions. The performance of various windows is evaluated with respect to shape factor and sidelobe level. Design data is presented for designing the surface acoustic-wave (SAW) filters using smooth window functions. The design of SAW filters using sin (t)/t-type apodization profile is outlined for various window functions. For given filter specifications, such as center frequency, 3-dB bandwidth, shape factor, and sidelobe level, the design procedure is used to compute the apodized transducer length and apodization profile. >

Design of SAW bandpass filters using new window functions

A novel analytical model for the threshold voltage of long-channel MOSFETs with implanted channels is presented. The model is simple from a computational point of view and yields accurate values of the threshold voltage, if the implant profile is gaussian. The analytical difficulty posed by the gaussian function to solve Poisson's equation has been removed by the use of a new integrable function that closely fits with the gaussian and a doping transformation based on a piecewise averaging approximation. The use of this function opens the way to a new technique of modelling semiconductor devices with gaussian doping. The threshold voltage and the profiles of potential and electric field inside the channel are calculated from their closed-form expressions for different doping and biasing conditions. The accuracy of the model is established by comparison with the results of the numerical solution for a gaussian doped channel and some experimental results. The possibilities of extending the model to short-cha...

A novel analytical threshold voltage model of MOSFETs with implanted channels

A now window function based on modified Bessel functions has been proposed. The Courier transform of the window function is obtained analytically. Computation of the Fourier transform shows a slight improvement over the Kaiser-Bessel window for suitable choice of parameters. The proposed function involves a simpler and faster computational method than that of the Kaiser-Bessel window.

On window functions

In this paper, the frequency dependence of scattering parameters of simple bidirectional transducers and group-type unidirectional transducers have been studied using cross-field model equivalent circuit. The analytical expressions for scattering parameters developed are simple for the purpose of computation. The scattering parameters were also measured experimentally for transducers fabricated on Y-cut, Z-propagating LiNbO3 substrate. The experimental curves of the different scattering parameters versus frequency agree generally with the theoretical curves.

Scattering Parameters of Interdigital and Group Type Unidirectional Saw Transducers

The process parameters of spin-on diffusion technique for the fabrication of single crystal silicon solar cells have been investigated in some detail. It is shown that a simple hydrophilic surface treatment before the thermal diffusion greately improves the uniformity of spin-on diffusion on texturised silicon solar cell. It is also reported that by suitably controlling the gas ambient during diffusion, the possibility of cross-contamination at the back surface can be reduced significantly.

Spin-On Diffusion for Silicon Solar Cell Fabrication

The admittance and scattering parameters of the SAW transducer are important in the design of various SAW devices. The frequency response of these parameters has been computed over a wide range of frequencies using an analysis based on a modified Mason equivalent circuit of the IDT which is not restricted to the ‘crossed-field’ and ‘inline-field’ approximations. Some of these simulated results agree satisfactorily with the experimental data available and theoretical results obtained earlier following other approaches.

S. K. Lahiri

Papers

A novel analytical threshold voltage model of MOSFETs with implanted channels

On window functions

Scattering Parameters of Interdigital and Group Type Unidirectional Saw Transducers

Spin-On Diffusion for Silicon Solar Cell Fabrication

Simulation of the frequency response of the admittance and scattering parameters of an SAW IDT