A Theoretical and Simulation Analysis of the Sensitivity of SiNWs-FET Sensors.

Yi Yang,Shixing Chen,Tie Li,Duo Liu,Yuelin Wang,Zicheng Lu

doi:10.3390/bios11040121

Abstract

Theoretical study and software simulation on the sensitivity of silicon nanowires (SiNWs) field effect transistor (FET) sensors in terms of surface-to-volume ratio, depletion ratio, surface state and lattice quality are carried out. Generally, SiNWs-FET sensors with triangular cross-sections are more sensitive than sensors with circular or square cross-sections. Two main reasons are discussed in this article. Firstly, SiNWs-FET sensors with triangular cross-sections have the largest surface-to-volume ratio and depletion ratio which significantly enhance the sensors’ sensitivity. Secondly, the manufacturing processes of the electron beam lithography (EBL) and chemical vapor deposition (CVD) methods seriously affect the surface state and lattice quality, which eventually influence SiNWs-FET sensors’ sensitivity. In contrast, wet etching and thermal oxidation (WETO) create fewer surface defects and higher quality lattices. Furthermore, the software simulation confirms that SiNWs-FET sensors with triangular cross-sections have better sensitivity than the other two types of SiNWs-FET sensors under the same conditions, consistent with the theoretical analysis. The article fully proved that SiNWs-FET sensors fabricated by the WETO method produced the best sensitivity and it will be widely used in the future.

Highlights

We analyzed the sensitivity of silicon nanowires (SiNWs)-field effect transistor (FET) sensors with three different cross-sectional shapes, along the same feature size W
Owing to the fact that the depletion ratio of SiNWs-FET sensors with triangular cross-section is larger than the others, it has the best sensitivity among these three types
Sensitivity, whichwe is given by that the sensitivity of SiNWs-FET sensors is affected by

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Thin film sensors and nanosensors are widely adopted for this mission because of their advantages in sensitivity [5,6,7]. Among these sensors, SiNWs-FET sensors have received increasing attention as they have ultrahigh sensitivity, which is necessary for the detection of these samples [8,9,10,11]. There are many factors, such as debye length [12], surface binding sites [13] and molecular affinities [14], that affect the sensitivity of SiNWs-FET sensors. The cross-sections of the SiNWs fabricated by these three methods are circular, square and triangular, respectively, which seriously.

Theoretical Analysis

Simulation

Conclusions