From Murmann Mixed-Signal Group
BSEE, POSTECH, 2006
MSEE, Stanford University, 2008
Admitted to Ph.D. Candidacy: 2007-2008
Research: Organic Transistors for Flexibe Electronics: fabrication and device physics
Organic transistors have shown promising potentials in flexible electronics. Because the transistors can be directly fabricated on flexible plastic substrates at low temperatures less than 100 °C, researchers envision development of novel electronic applications, such as flexible displays, flexible circuits, and conformal sensors. However, there are still several challenges to be solved for making practical applications, beyond laboratory-level demonstrations.
First we have demonstrated high-capacitance gate dielectric on plastic substrates using atomic layer deposition. This low-temperature process was used to fabricate high-performance flexible organic transistors. Also, we have utilized flexible shadow masks made of parylene-C for making small patterns on organic semiconductors. Due to their good adhesion on a variety of surfaces, the shadow masks patterned small feature sizes of less than 10 μm with high yield.
Second, we studied controlling current-voltage characteristics of organic transistors from the device physics point of view. Self-assembled monolayers and different gate electrodes were used to modify electric dipoles in the gate dielectric and gate work functions, respectively. Engineering the dipoles and the gate work functions provided a wide range of threshold voltage control over 0.6 V at a supply voltage of 2.5 V. We also found that the dipoles can be used to improve significantly the air stability of n-channel (electron conducting) organic transistors, which are generally not stable in air.