In metal-oxide thin-film transistors (TFTs), high-k gate dielectrics often yield a higher electron mobility than SiO2. However, investigations regarding the mechanism of this high-k “mobility boost” are relatively scarce. To explore this phenomenon, solution-processed In2O3 TFTs are fabricated using eight different gate dielectrics (SiO2, Al2O3, ZrO2, HfO2, and bilayer SiO2/high-k structures). With these structures, the total gate capacitance can be varied independently from the semiconductor–dielectric interface to study this mobility enhancement. It is shown that the mobility enhancement is a combination of the effects of areal gate capacitance and interface quality for disordered oxide semiconductor devices. The ZrO2-gated TFTs achieve the highest mobility by inducing more accumulation charge with higher gate capacitance. Surprisingly, however, when the gate capacitance is held constant, no mobility enhancement is observed with the high-k gate dielectrics compared to SiO2.
Bibliographical noteFunding Information:
This material was based upon work supported by the National Science Foundation under Grant No. ECCS‐1710008, and through the University of Minnesota MRSEC under Award Number DMR‐2011401. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. Portions of this work were conducted in the Minnesota Nano Center, which is supported by the National Science Foundation through the National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS‐2025124. The authors expressed their appreciation to Prof. Paul Ruden for his valuable guidance and constructive feedback while developing the device model.
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- colloidal In O nanocrystals
- field-effect mobility
- high-k gate dielectrics
- metal-oxide semiconductors
- thin-film transistors