Stable InSe transistors with high-field effect mobility for reliable nerve signal sensing

Jianfeng Jiang,Hong Liu,Yu Zhang,Linshen Li,Qiqiang Li,Lin Han,Ye Tian,Zhihua Zong,Jiazhzhi Duan,Yutao Li,Tian-Ling Ren,Haotian Zheng,Jingxin Li,Xianjin Feng

doi:10.1038/s41699-019-0110-x

Abstract

Among two-dimensional layered semiconductors, indium selenide (InSe) is one of the most promising materials with absolute advantages in field-effect transistors (FETs) because of its high electron mobility and stable material properties. Some work has been performed to improve the mobility of InSe FETs. However, in practical applications, electrical stability of FETs is another essential factor to guarantee the performance of the electronic system. Here, we show a highly stable InSe FET with a field-effect mobility of 1200 cm2/V·s in the practical working regime. The bottom-gate staggered InSe FET was fabricated with a polymethyl methacrylate (PMMA)/HfO2 dual-layer gate dielectric and PMMA back-channel encapsulation. The hysteresis was maintained at 0.4 V after 30 days of storage under normal ambient conditions, and the threshold voltage shift was retained at 0.6 V with a gate stress VGS of 10 V, which represents the best electrical stability reported to date. Its high mobility and electrical stability enable reliable detection of the weak nerve action potential at a low power consumption. High-performance InSe FETs expand their promising applications in flexible and in situ real-time intelligent nerve action potential recording.

Highlights

Among 2D materials, indium selenide (InSe), a layered semiconductor made of stacked layers of Se-In-Se atoms, holds great promise because of its high intrinsic mobility and moderate electronic band gap (1.26 eV).[10,11,12]
The fabrication of our transistors started with deposition of a 30 nm HfO2 layer on a highly doped Si wafer by an atomic layer deposition (ALD) system at 150 °C and spin-coating of a 250 nm polymethyl methacrylate (PMMA) layer on HfO2, which function as the dual-layer dielectric (Fig. 1a, b)
The thickness of the InSe flake was determined by atomic force microscopy (AFM)

Summary

Introduction

Two-dimensional (2D) materials have attracted intensive attention because of their unique electronic structure and transport properties.[1,2,3,4,5,6,7,8,9] Among 2D materials, indium selenide (InSe), a layered semiconductor made of stacked layers of Se-In-Se atoms, holds great promise because of its high intrinsic mobility and moderate electronic band gap (1.26 eV).[10,11,12] Previous work has been performed to improve the mobility of InSe field-effect transistors (FETs) and other 2D material-based FETs.[13,14,15] For instance, (1) Heterojunction structure,[16] (2) high-k dielectric,[1,13] (3) high-k encapsulation,[17] and (4) Chemical and physical interface engineering[15,18,19] have been used to enhance the carrier mobilities of 2D materials based FETs. Based on the high electrical stability and field-effect mobility, InSe FETs allow us to conduct the real-time and in situ detection of frog sciatic action potential.

Results

Conclusion