Total-Ionizing-Dose Effects and Low-Frequency Noise in N-Type Carbon Nanotube Field-Effect Transistors With HfO₂ Gate Dielectrics

Total ionizing dose (TID) irradiation and low-frequency noise characterization are performed on carbon nanotube field-effect transistors (CNTFETs). Large hysteresis due to high border-trap densities is observed in as-processed and irradiated devices. TID irradiation also leads to significant radiation-induced charge trapping in the surrounding dielectrics resulting in parametric degradation. Percolation-path switching and border traps contribute to low-frequency noise, with a relatively more prominent role for border traps after irradiation than before irradiation. These results show that process improvements are required to optimize both the initial operating characteristics and the radiation response of CNTFETs.

I. Introduction

Semiconducting single-walled carbon nanotubes (SWCNTs) are a promising alternative to silicon as the channel material for future microelectronics [1]. Due to their high carrier mobility, high current density, 1 nm diameter, and exceptional electrostatic control, SWCNTs are well suited for high-speed aggressively scaled transistors [2], [3], [4]. Because of these intrinsic properties and the potential for 3-D monolithic system-on-a-chip (3-DSoC) integration, there has been much interest in recent years in the development of SWCNT transistors [carbon nanotube field-effect transistors (CNTFETs)] for use in high-performance digital circuits [1], [5], [6].