REALIZATION AND MODELING OF WATER-GATED FIELD EFFECT TRANSISTORS (WG-FET) USING 16-NM-THICK SINGLE CRYSTALLINE SILICON FILM AND THEIR CIRCUIT APPLICATIONS

This thesis covers realization and modeling of novel water-gated field effect transistors (WG-FETs) which use 16-nm-thick single crystalline silicon film as active layer. WG-FET devices utilize electrical double layer (EDL) structure as a replacement of gate insulator and operate in the non-Faradaic region (under 1 V) without causing any oxidation/reduction reactions. Performance parameters based on voltage distribution on EDL are extracted and current-voltage relations are modeled. Various WG-FET devices with both probe- and planar-gate setups are simulated, fabricated and tested. Effects of gate distance, gate topology, field and source/drain electrode insulation on transistor performance are investigated. Best ON/OFF ratios are measured with probe-gate devices for both insulated and uninsulated source/drain electrodes. Performance of probe-gate devices with uninsulated source/drain electrodes are superior to the ones with insulated source/drain due to absence of parasitic resistances related with the overlapping area of insulation layer. Planar-gate devices with source/drain insulation have lower ON/OFF ratios compared to probe-gate counterparts and device performance tends to deteriorate with increasing gate distance. Without source/drain electrode insulation, proper transistor operation is not obtained with planar-gate devices. Measurement results are in agreement with theoretical models. Inverters and ring oscillators are realized as circuit applications. Also, a sensing application is implemented as proof of concept. WG-FET is a promising device platform for microfluidic applications where sensors and read-out circuits can be integrated at transistor level.

 

ABOUT SPEAKER:

 

Bedri Gürkan SÖNMEZ received his B.Sc. degrees in Physics and in Electrical & Electronics Engineering in 2009, and M.Ss. degree in Electrical & Electronics Engineering in 2011 from Bogazici University, Istanbul, Turkey. His M.Sc. studies were about liquid state diodes using polymer semiconductors. He is currently pursuing the Ph.D. degree in microfluidic electronics and circuit applications.