Dr.Gokirmak-Faculty Candidate: A Side-Gated Silicon nMOSFET for Field Effect Transistor Based Sensing

In recent years there has been a significant effort in building micro/nano fluidic systems using the tools developed for the semiconductor industry. Successful integration of field effect transistors with nano-fluidic systems can lead to extremely sensitive charge detectors which can be used for identification of large molecules in liquid samples. We have developed techniques to monolithically integrate an ultra-narrow-channel field effect transistor (FET) with a nanoscale pore for fluidic delivery for ultra-sensitive detection. The micro-fluidic delivery employs silicon nitride based shallow trench isolation (STI) and achieves electrical isolation. The channel widths of the FETs, fabricated on bulk Si, are as low as sub-10 nm with remarkable uniformity. The gates of these FETs are suspended 10 to 30 nm above their channels. Liquid sample, delivered by the micro-fluidic tunnels, is passed between the gate and the electron channel of the FET. The FET structures are designed to detect local charge variations along the denatured biomolecules to reveal the sequence information by monitoring the variations in drain current as the sample travels between the gate and the channel of the FET. Leakage currents in this system are significantly reduced with the employment of an additional, independently controlled side-gate surrounding the active areas of the devices.
Ali Gokirmak has completed his Bachelor of Science degree in electrical engineering and physics at University of Maryland at College Park in 1998. He has joined the MS/PhD program at Cornell University in 1998. He is currently working towards completing his doctoral degree. His work focuses on ultra-narrow channel Si FETs and integration of these structures with micro-fluidics for sensor applications. His current research interests include small-scale solid-state devices for sensors, digital, analog, non-volatile memory device applications, integration of MEMS and micro/nano-fluidics with electronics and nanofabrication techniques.