Silicon nanowires are leading the CMOS era towards the downsizing limit and its nature will be effectively suppress the short channel effects. Accurate modeling of thermal noise in nanowires is crucial for RF applications of nano-CMOS emerging technologies. In this work, a perfect temperature-dependent model for silicon nanowires including the self-heating effects has been derived and its effects on device parameters have been observed. The power spectral density as a function of thermal resistance shows significant improvement as the channel length decreases. The effects of thermal noise including self-heating of the device are explored. Moreover, significant reduction in noise with respect to channel thermal resistance, gate length, and biasing is analyzed.

As the device size scaling continues, many critical issues such as increased leakage current, short-channel effect, high-field effects, variability, reliability, noise, and parasitic impacts may pose more obstruction for highly scaled devices. Therefore, device structure and material innovation have attracted more attention as the primary enabler for performance enhancement in CMOS technology.

The gate-all-around (GAA) silicon nanowire transistor (SNWT) is considered as one of the promising candidates for ultimate scaling, due to its excellent electrostatic control capability, improved transport property, and feasible device design [

Channel thermal noise is the most dominant noise source of short-channel MOSFETs at high frequencies. As the MOSFET is scaled down, short-channel effects increase and it causes serious problems in device operation. Gate-all-around silicon nanowire MOSFET is one of the strong candidates, which has high performance even in short-channel devices [

Structure of SNWFET.

Before analyzing the channel thermal noise, the DC characteristics of SNWFET are analyzed. From Figure

In this work, channel thermal noise of the silicon nanowire MOSFET (SNWFET) is derived from the analytic thermal noise model, by including short-channel effects [

Using (

Considering the short-channel effects, the power spectral density of channel thermal noise is validated for short-channel transistors as follows:

Special design approaches are derived for SNWT circuits by using the thermal model; the effect can be analyzed for the devices with the following relationship between temperature dependence and power dissipation [

Once the temperature dependence of the device parameters is extracted, the same approach can be used for describing the self-heating effects of the device:

Substituting self-heating effect in power spectral density equation of channel thermal noise,

In SNWTs, the self-heating problem may be even worse due to their ultrasmall and strongly confined nanowire channels. Therefore, a simple and accurate analytical channel thermal noise model for SNWTs is developed and optimized for future applications.

In recent years, some effort has been devoted to the numerical simulation of noise phenomena in physics based device simulators. In most cases, the noise simulation is founded on Shockley’s impedance field method [

Diffusion noise is due to fluctuations of the velocities of the carriers, caused by collisions with phonons, impurities, temperatures, and so forth. The following expression for the electron diffusion noise source can be derived (e.g., [

Figure

(a) Power spectral density of channel thermal noise versus drain source voltage of the SNWMOSFET. (b) Power spectral density of channel thermal noise versus drain current of the SNWMOSFET.

The effect of drain current with PSD of channel thermal noise is modeled in Figure

Figure

(a) Power spectral density of channel thermal noise versus channel length of the SNWMOSFET. (b) Power spectral density of channel thermal noise versus thermal resistance of the SNWMOSFET.

Figure

Figure

Power spectral density of channel thermal noise versus thermal resistance of the SNWMOSFET.

Figure

(a) Characteristic of minimum noise factor versus gate length. (b) Characteristic of minimum noise factor versus drain voltage.

Figure

Figure

(a) Characteristic of temperature versus drain current. (b) Characteristic of temperature versus area of SNW.

Figure

Figure

Characteristic of PSD of channel thermal noise versus temperature.

This paper analyses the modeling of thermal noise in silicon nanowire MOSFET including the self-heating effects. The variations of thermal noise with respect to various device oriented parameters are observed for improved performances of the device. The channel thermal noise is predicted using noise factor in silicon nanowire MOSFET at high frequencies. Improvement in noise figure owing to reduce area in case of effectively scaled Nanowires.

An analytical formulation of the thermal noise in short-channel MOSFETs, working in the saturation region, is presented. Hence, the noise characteristic is analyzed by noise factor and the performance of the noise characterized by TCAD shows significant improvement in case of suitably scaled nanowires. The effects of thermal noise with respect to device geometry are discussed in detail.

The authors declare that there is no conflict of interests regarding the publication of this paper.