Local electronic structures in Field Effect Transistors by synchrotron radiation photoelectron nano-spectroscopy

by Prof. Masaharu Oshima (University of Tokyo, Japan )

Wednesday 12 Jun 2019, 16:00 → 17:00 Europe/Rome

Aula Seminari PT (NEST)

In order to investigate local electronic structures in nano-materials/devices, we have developed soft X-ray photoelectron nano-spectroscopy with 70 nm spatial resolution at SPring-8 in Japan, where the sample holder is connected to a semiconductor parameter analyzer to facilitate operando pin-point analysis during device operation. Among several FETs, the first example is a graphene FET where we discovered the linear band dispersion in graphene FET by operando nano-spectroscopy. The second FET is a MoS2 nanolayer FET which did not exhibit as good performance as expected. We have performed pin-point analysis to investigate the local electronic structure at interfaces in a MoS2 FET, and observed a charge-transfer region (CTR) at the MoS2/metal-electrode interface. The third FET is an organic semiconductor FET (OFET) for light weight, flexible electronics with low cost. Operando measurements of line profiles of C 1s kinetic energy across the OFET channel composed by ultrathin single-crystalline C10-DNBDT-NW films suggest that drain current proportional to hole concentration in the channel generated by the back gate biasing is well correlated by the simple Boltzmann distribution. Finally, the forth FET is a 4H-SiC trench MOSFET. We conducted pin-point analysis of RIE (reactive ion etching)-processed trench sidewall, because chemical and electronic structures of the sidewall which is the MOS channel plane directly affect the FET performance. Nano-spectroscopy revealed local chemical structure and band bending features caused by RIE damages. The fifth FET is GaN HEMT for mm-wave frequency domain where we have revealed surface electron trap density by operando analysis. Future prospects of brighter synchrotron radiation nano-spectroscopy will be discussed.