Low Power Switching Characteristics of CNT Field Effect Transistor Device with Al-Doped ZrHfO2 Gate Dielectric

Seyoung Oh,Jeong-Hun Choi,Seung Won Lee,Dongjun Kim,Ji-Hoon Ahn,Hong-Chul Chae,Byungjin Cho,Sung Mook Choi

doi:10.1155/2018/2156895

Abstract

In this report, we demonstrated a reliable switching effect of carbon nanotube (CNT) field-effect transistor (FET) devices integrated with 99% semiconducting CNT as a channel and high-k oxide as the dielectric. CNT FET devices with high-k oxides of Al-ZrHfO2 and Al2O3 were electrically characterized and compared. There was no considerable hysteresis in the Al2O3-based CNT FET device. The Al-ZrHfO2 with a tetragonal phase-based high dielectric constant (~47), designed by an atomic layer deposition process, showed a reliable switching effect as well as low operation voltage (<±3 V). Charge trapping/detrapping process via oxygen vacancy-related defects of Al-ZrHfO2 was proposed as a primary mechanism to explain a current change of a counterclockwise direction and threshold voltage (Vth) shift for transfer properties. The suggested charge trapping model within bulk oxide was experimentally proven since the hysteresis from the adsorption/desorption of gas molecules to CNT surface was negligible. Endurance characteristics of the CNT switching devices remained stable without any serious current fluctuation during a repetitive cycling test. The memory device with reliable switching properties as well as low operation power would pave a road toward next-generation memory components of portable electronic gadgets.

Highlights

Carbon nanotube (CNT) has been considered as a promising building block for next-generation electronics such as electronic transistor and sensor since they possess extraordinary physical properties [1,2,3,4]
The abrupt size reduction of dynamic random-access memory (DRAM) cell keeps pushing on the development of new high-k dielectric materials
Al2O3 and Al-ZrHfO2 thin films were deposited on heavily doped p-type Si substrate (p+ Si, resistivity < 0.005 Ω⋅cm) using plasma-enhanced atomic layer deposition (PEALD)

Summary

Introduction

Carbon nanotube (CNT) has been considered as a promising building block for next-generation electronics such as electronic transistor and sensor since they possess extraordinary physical properties [1,2,3,4]. Owing to the nanoscale diameter and large carrier mobility in CNT, the CNTbased electronic memory devices have achieved ultimate integration, high switching ratio, fast switching speed, low power consumption, and nonvolatile information storage capability [5,6,7]. Doping strategy to stabilize the tetragonal ZrO2 or HfO2 has been concentrated on the development of high dielectric constant oxide materials [11, 12]. Integration of CNT nanomaterials and high-k dielectric materials with intrinsically electronic trap states is highly required to realize low-powered switching devices, which has rarely been studied. The novel Al-ZrHfO2 with a tetragonal phase-based high dielectric constant (~47), deposited by ALD method, allowed a reliable switching effect as well as low operation voltage (

Materials and Experimental Method

Result and Discussion

Conclusions