| PhD Viva

Name of the Speaker: Mr. Logesh K (EE12D015)
Guide: Dr. Soumya Dutta
Online meeting link: https://meet.google.com/yyk-jrjk-hht
Date/Time: 24th April 2025 (Thursday), 3:00 PM
Title: Metal-Semiconductor Junction Induced Effects in Organic Field Effect Devices

Abstract :

In this presentation, we focus on the influence of the metal-semiconductor interface on the device performance. Uncontrolled hysteresis in transfer characteristics is one of the major concerns that cause different drain currents (IDS) for a particular gate voltage (VGS), depending on the direction of the voltage sweep. This can result in a serious issue for circuit application as a consequence of the shift in threshold voltage. In the present study, we investigate the role of metal-semiconductor junction in hysteresis, which eventually becomes more prominent while scaling down the device dimension. Based on the experimental signature and the correlation between contact resistance and hysteresis, we demonstrate the route to reduce/mitigate that issue. To explore the influence of metal-semiconductor contact on field-effect devices, we study organic metal-insulator-semiconductor (MIS) capacitor, which is considered a model device structure to comprehend the transistor operation. In this context, we discuss the operation of organic MIS capacitors, the concept of unintentional doping, the validity of the Mott-Schottky relationship, and the role of metal-semiconductor junction in capacitance dispersion as a function of operating frequency. Apart from commercially available organic semiconductors, we also implement in-house synthesized organic semiconductors as active materials for OFETs and explore the chemical tunability of the semiconductors to achieve high charge injection at the metal-semiconductor junction for improved device performance.