Characteristics of GaAs/GaSb tunnel field-effect transistors without doping junctions: numerical studies

Abstract

Tunneling field-effect transistor (TFET) suffers from ultra-sharp doping concentration gradients in both the source/channel junction and drain/channel junction. Recently, the junctionless (JL) TFET device has been proposed to avoid the issue of ultra-sharp doping concentration gradients. Employing III---V semiconductor as a drain/channel material and a group IV semiconductor as a source material has been proposed to improve the heterojunctionless (HJL) TFET device performance. GaAs:Ge HJL-TFET has proved more efficient than other HJL-TFET structures in providing more ON-state current, less OFF-state current, and less subthreshold slope (SS). For the first time in this paper, GaSb as the source material and GaAs as the drain/channel material have been proposed. This is the so-called GaAs:GaSb HJL-TFET structure. Simulation results show that the GaAs:GaSb HJL-TFET provides improvement in both $$I_{\mathrm{ON}}/I_{\mathrm{OFF}}$$ION/IOFF ratio and SS as compared to GaAs:Ge HJL-TFETs. We demonstrate that for a 20 nm channel length, the GaAs:GaSb HJL-TFET average SS is improved by 19% and the point slope by 52%, as compared to those of the GaAs:Ge HJL-TFET. Numerical simulations show that the average SS and $$I_{\mathrm{ON}}/I_{\mathrm{OFF}}$$ION/IOFF ratio of GaAs:GaSb HJL-TFET are nearly 9 mV/dec and 3E12, respectively, for a 10 nm channel length. Thus, the GaAs:GaSb HJL-TFET holds promise for future logic transistor applications.