High Performance of Liquid-Gated Silicon Nanowire FETs Covered with Ultrathin Layers of Diamond-Like Tetrahedral Amorphous Carbon

Label-free, low-noise, and ultrahigh-sensitive biosensors based on liquid-gated silicon (Si) nanowire (NW) field-effect transistors (FETs) have recently emerged as promising diagnostic tools that can be used for healthcare monitoring and point-of-care applications. However, the sensing capabilities and performance of such devices still critically depend on several factors, including the quality and intrinsic properties of the materials used. In particular, the important role of determining device performance is assigned to the gate insulator layer, which acts as a sensing surface in such NW-based biosensors and still requires optimization. Herein, several advanced multilayer structures: Si NW/SiO2/diamond-like carbon FETs, are investigated. The high quality of the diamond-like carbon layer obtained by low-temperature physical vapor deposition is confirmed by X-ray photoelectron spectroscopy and Raman spectroscopy studies. Current–voltage and noise spectroscopy reflect the high-quality transport properties in these structures.