16November2018

Nano-Micro Letters

Observation of Van Hove Singularities and Temperature Dependence of Electrical Characteristics in Suspended Carbon Nanotube Schottky Barrier Transistors

Jian Zhang1, 2, Siyu Liu1, Jean Pierre Nshimiyimana1, 2, Ya Deng1, 2, Xiao Hu1, 2, Xiannian Chi1, 2, Pei Wu1, 2, Jia Liu1, 2, Weiguo Chu1, *, Lianfeng Sun1, *

Abstract
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Nano-Micro Lett. (2018) 10: 25

First Online: 24 October 2017 (Article)

DOI:10.1007/s40820-017-0171-3

*Corresponding author. E-mail: slf@nanoctr.cn ; wgchu@nanoctr.cn

 

Abstract

 


Fig. 1 a Schematic of the electronic band structure (left) and DOS (right) of a semiconducting SWNT. Four sharp VHSs (VHS 1+, VHS 1−, VHS 2+, VHS 2−) appear at the onset of each subband. b Typical SEM image of a back-gate SWNT transistor. The SWNT is suspended, and the channel length is about 1 μm. c Schematic of the suspended SWNT transistor. The height of the suspended SWNT and the thickness of the insulating layer (SiO2) are 500 and 800 nm, respectively

A Van Hove singularity (VHS) is a singularity in the phonon or electronic density of states of a crystalline solid. When the Fermi energy is close to the VHS, instabilities will occur, which can give rise to new phases of matter with desirable properties. However, the position of the VHS in the band structure cannot be changed in most materials. In this work, we demonstrate that the carrier densities required to approach the VHS are reached by gating in a suspended carbon nanotube Schottky barrier transistor. Critical saddle points were observed in regions of both positive and negative gate voltage, and the conductance flattened out when the gate voltage exceeded the critical value. These novel physical phenomena were evident when the temperature is below 100 K. Further, the temperature dependence of the electrical characteristics was also investigated in this type of Schottky barrier transistor.


 

Keywords

Carbon nanotube; Van Hove singularities; Schottky barrier transistors

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