O2 plasma treated biosensor for enhancing detection sensitivity of sulfadiazine in a high-к HfO2 coated silicon nanowire array

Abstract

In this paper, highly uniform silicon nanowire (SiNW) arrays (∼30 nm in diameter) used as FET biosensors are fabricated by using a CMOS-compatible spacer image transfer (SIT) technology with high efficiency compared with conventional electron beam (E-beam) lithography. An effective biochemical sensing approach that treated with optimization of O2 plasma on the SiNW biosensors coated with a 10 nm HfO2 high dielectric constant (high-к) film is demonstrated to enhance immobilization of antibodies. Furthermore, water contact angle (WCA) measurements verify that the increased number of hydroxyl groups (OH) on the HfO2 surfaces treated with O2 plasma reaches or surpasses that on a conventional SiO2 surface. Therefore, it is observed that the IDS/I0 is enlarged by 3.15 times compared with that of the HfO2 surface without O2 plasma treatment. In addition, real-time and label-free detection of sulfadiazine with high sensitivity and specific recognition is successfully achieved using the SiNW FET biosensor with the optimized process. And a 10 pg⋅mL−1 limit of detection (LOD) is achieved for the SiNW FET biosensor using O2 plasma treatment on an ultrathin HfO2 mentioned above. The proposed O2 plasma treatment on HfO2 provides an effective solution for future FET biosensors coated with high-к dielectrics.