Effects of UV-Ozone Treatment on Sensing Behaviours of EGFETs with Al₂O₃ Sensing Film.

Cuiling Sun,Junkai Zhang,Dongping Wu,Zhi-Jun Qiu,Ruixue Zeng

doi:10.3390/ma10121432

Abstract

The effects of UV-ozone (UVO) treatment on the sensing behaviours of extended-gate field-effect transistors (EGFETs) that use Al2O3 as the sensing film have been investigated. The Al2O3 sensing films are UVO-treated with various duration times and the corresponding EGFET sensing behaviours, such as sensitivity, hysteresis, and long-term stability, are electrically evaluated under various measurement conditions. Physical analysis is also performed to characterize the surface conditions of the UVO-treated sensing films using X-ray photoelectron spectroscopy and atomic force microscopy. It is found that UVO treatment effectively reduces the buried sites in the Al2O3 sensing film and subsequently results in reduced hysteresis and improved long-term stability of EGFET. Meanwhile, the observed slightly smoother Al2O3 film surface post UVO treatment corresponds to decreased surface sites and slightly reduced pH sensitivity of the Al2O3 film. The sensitivity degradation is found to be monotonically correlated with the UVO treatment time. A treatment time of 10 min is found to yield an excellent performance trade-off: clearly improved long-term stability and reduced hysteresis at the cost of negligible sensitivity reduction. These results suggest that UVO treatment is a simple and facile method to improve the overall sensing performance of the EGFETs with an Al2O3 sensing film.

Highlights

The ion-sensitive field-effect transistor (ISFET) was first developed by Bergveld in 1970, which were initially used for pH detection and ion concentration measurement [1,2]
The effects of UVO treatment on the sensing behaviours of extended-gate field-effect transistors (EGFETs) based on Al2O3 sensing film
The effects of UVO treatment on the sensing behaviours of EGFETs based on Al2 O3 sensing have been studied

Summary

Introduction

The ion-sensitive field-effect transistor (ISFET) was first developed by Bergveld in 1970, which were initially used for pH detection and ion concentration measurement [1,2]. The EGFET allows the reuse of the MOSFET and a flexible shape of the sensing structure Over these years, materials used as EGFET sensing films have been investigated, such as tin dioxide (SnO2 ), tantalum pentoxide (Ta2 O5 ), vanadium pentoxide (V2 O5 ), and so on [7,9,10]. Materials used as EGFET sensing films have been investigated, such as tin dioxide (SnO2 ), tantalum pentoxide (Ta2 O5 ), vanadium pentoxide (V2 O5 ), and so on [7,9,10] Among these materials, Al2 O3 is considered as a suitable sensing material from the point of view of its inert characteristic, high sensitivity, good ion selectivity, and compatibility with the complementary metal oxide semiconductor (CMOS) process [11]

Methods

Findings

Discussion

Conclusion