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

Carbon nanotubes (CNTs) are promising materials for the formation of field-effect transistors (FETs) due to their excellent electrical, thermal, mechanical and other properties. High productivity, low power consumption, minimization of the impact of short-channel effects, etc., are of significant practical interest primarily to coaxial CNTFETs. This paper presents the results of numerical simulation of coaxial gate-all-around (GAA) CNTFETs. The structure of GAA CNTFETs is designed using Silvaco TCAD tools and their electrical parameters are investigated. The drift diffusion model of transport, taking into account the Bohm quantum potential, demonstrates excellent characteristics for three-dimensional models, in particular, valid values are obtained for the threshold voltage Vt, subthreshold swing SS, switching current Ion, leakage current Ioff and Ion/Ioff coefficient. The influence of temperature on the specified electrical parameters at low bias voltages is studied and the typical character of temperature dependences for semiconductor devices is obtained. It is established that the values of the threshold voltage Vt and subthreshold swing SS decrease and increase, respectively, with increasing temperature from 250 to 500 K. Along with this, there is a slight decrease in the switching current by 1.6 % in a given temperature range at the source voltage V_DD = – 1.0 V. The thermal stability of coaxial structures of nanotransistors with a channel in the form of a single-walled CNT is evaluated by the temperature coefficients β_Vt, β_SS, β_Ion and β_Ioff, which at V_DS = 0.10 V are respectively 3.2·10 ^– 4 K ^– 1, 3.2·10 ^– 3 K ^– 1, – 6.2·10 ^– 5 K ^– 1 and 1.0·10 ^– 4 K ^– 1.