Manh Cuong Nguyen

Li-Assisted Low-Temperature Phase Transitions in Solution-Processed Indium Oxide Films for High-Performance Thin Film Transistor

Lithium (Li)-assisted indium oxide (In2O3) thin films with ordered structures were prepared on solution-processed zirconium oxide (ZrO2) gate dielectrics by spin-casting and thermally annealing hydrated indium nitrate solutions with different Li nitrate loadings. It was found that the Li-assisted In precursor films on ZrO2 dielectrics could form crystalline structures even at processing temperatures (T) below 200 °C. Different In oxidation states were observed in the Li-doped films, and the development of such states was significantly affected by both temperature and the mol% of Li cations, [Li+]/([In3+] + [Li+]), in the precursor solutions. Upon annealing the Li-assisted precursor films below 200 °C, metastable indium hydroxide and/or indium oxyhydroxide phases were formed. These phases were subsequently transformed into crystalline In2O3 nanostructures after thermal dehydration and oxidation. Finally, an In2O3 film doped with 13.5 mol% Li+ and annealed at 250 °C for 1 h exhibited the highest electron mobility of 60 cm2 V−1 s−1 and an on/off current ratio above 108 when utilized in a thin film transistor.

Improved Electrical Properties of Solution-Processed ZrO2 Gate Dielectric for Large-Area Flexible Electronics

Zirconium oxide (ZrO2), which has high dielectric constant, was investigated for application in flexible electronics. When the spun-cast film was annealed at a low temperature, the electrical properties were not encouraging because residual organic particles remained at the dielectric. To address this problem we used plasma annealing at a reasonably low temperature and achieved improved dielectric properties such as lower leakage current, higher dielectric constant, and better reliability. Auger depth profile spectroscopy results suggested reduction of carbon percentage at the dielectric. We demonstrated device application by fabricating transistor device with an organic channel layer. The transistor electrical properties were encouraging, exhibiting an electron mobility of 0.3 cm2/(V·s). The results were very promising and suggest that ZrO2 could be applied to all-printed electronic devices in the near future.

Characterization of high pressure hydrogen annealing effect on polysilicon channel field effect transistors using isothermal deep level trap spectroscopy

Effect of high pressure hydrogen annealing on polysilicon thin film transistors has been evaluated using a novel acquisition setup and analysis of deep trap states. Trap density was extracted with high resolution of density and energy level. Trap density was reduced by one order of magnitude after annealing. Passivation effect was maintained even after a strong hot carrier injection stress.

Observation of Scattering Effect on Carrier Mobility of MOSFET with La-incorporated-HfO 2 Gate Dielectric

Using cryogenic measurement (from 100K to 300K) we have investigated scattering mechanisms of nMOSFET with La-incorporated-HfO2 dielectric. As the content of La incorporation in the dielectric increases, the more increase of maximum effective mobility has been found at the cryogenic temperature. It is mainly attributed to the reduction of optical phonon scattering due to higher content of La atoms at the interface of dielectric and channel. Though it is relatively small, the existence of La in dielectric reduces Coulomb scattering rate as well.