Numerical Simulation of Field-effect Transistorwith a Channel in the Form of a Nanowire

Abstract

The operation of the basic functional element of the integrated circuit -the field-effect transistor -is based on the drift of electrons and holes in the Si channel. With the use of stretching-compression of the crystal lattice of the Si substrate, by introducing impurity atoms, the mobility of carriers is somewhat reduced. At the same time, considerable interest to nanowires (NWs) based on Si (Ge) solid solution as elements for the formation of highly efficient channels of field-effect transistors necessitates studies of their structural, electrical and temperature characteristics. The paper presents the results of numerical simulation of coaxial Si-channel gate-all-around (GAA) FET structures. The structure of the n-type GAA NWFET and its volt-ampere characteristics were constructed using Silvaco TCAD tools. Within the framework of the diffusion-drift model of carrier transport, taking into account the Bohm quantum potential, effective operating parameters were obtained: permissible values of the threshold voltage, leakage current and Ion/Ioff coefficient, and their dependences on temperature. It was obtained that the values of the threshold voltage Vt and subthreshold scattering SS remain almost unchanged with increasing temperature in the range from 280 to 400 K, which is primarily due to the additional influence of quantum effects for a given channel thickness and impurity concentrations. In addition, a typical decrease in the switch-on current by 45.5 % and leakage current by 46.4 % in a given temperature range was recorded. To assess the thermal stability of the studied transistor systems, the temperature coefficients Vt, SS, Ion and Ioff were calculated. Their values were respectively 8.6310 -5 ; -0.5310 -5 ; -3.8710 -3 and -3.8010 -3 K -1 . The results of numerical simulations showed good agreement with the experimental data.

Electrical and Temperature Characteristics of Transistors with a Channel in the Form of a Carbon Nanotube

“…As an example, the threshold voltage can have different values determined by the values of the work functions of gate materials (channel conductivity type) [10], Schottky barriers at the metal electrode/semiconductor nanotube contact points [23], charges on the oxide surface near the nanotube [6] and other factors.…”

“…In addition, the compact simulation data of GAA CNTFETs indicate high thermal stability of their electrical parameters and the possibility of wide application, although there is a problem of significant leakage current, low reproducibility of parameters in the manufacture of such devices, etc. In terms of heat resistance, the results show an improvement in the performance of CNTFETs compared to FETs with Fin or nanowire channels [23].…”