Quantitative Semiconductor Nanosensors

Nanoscale Field Effect Transistors (FETs) have emerged as a promising technology for ultrasensitive and unlabeled diagnostic applications; however their practical use has been hindered by the lack of methods for quantitative sensing and more importantly the detailed understanding of the relationship between sensitivity and dimensional scaling. In this work we explore the fundamental relationship between the electrical and sensing properties of nanoscale FET and introduce methods for quantitative sensing and internal sensor calibration. By developing top-down fabrication processes for Complementary Metal Oxide Semiconductor (CMOS) compatible Silicon-On-Insulator (SOI) nanowire and nanoribbon FET arrays we demonstrate multiplexed detection of bimolecular species which ultimately leads to an internal calibration scheme for molecular quantification. We apply this method to two different detection schemes. First, we investigate label-free detection of biomolecules -- e.g. cancer biomarkers and successfully demonstrate calibration curves and quantification with lower relative standard error of the mean compared to traditional Enzyme Linked ImmunoSorbent Assay (ELISA). Second, we investigate the relationship between nanoscaleFET sensor operation and size scaling by comparing experimental data and developing new theoretical models. Finally, we introduce the Debye Length modulation technique which allows probing of the surface functionalization and determining the average spatial extent of bound surface charge. For the first time since the foundation of the FET based sensor field we demonstrate their application as quantitative tools. This step is our determination to bring the field forward towards creation of a powerful point-of-care diagnostic tool.