Crystallization of (Hf, Zr)O-2 thin films via non-heating process and their application to ferroelectric-gate thin film transistors

HfO2-based ferroelectric materials do not necessarily require high-temperature annealing for crystallization, making them attractive for applications in transparent electronic devices on plastic or glass substrate. In this study, (Hf, Zr)O-2 (HZO) films prepared via non-heating sputtering are investigated and their application to ferroelectric-gate thin-film transistors (TFTs) is demonstrated. The internal tensile stress induced by (In, Sn)O (x) (ITO) top-electrode deposition is found to promote the crystallization of HZO from the amorphous state to the ferroelectric phase. ITO/HZO (15-25 nm)/ITO capacitors prepared via the non-heating process exhibit ferroelectric hysteresis loops with remanent polarizations of 6-9 & mu;C cm(-2) and coercive fields of 0.6-1.1 MV cm(-1). Ferroelectric-gate TFTs with a 10 nm thick ITO channel are also fabricated via the non-heating process. These TFTs show nonvolatile operation with an on/off ratio of & SIM;10. These findings demonstrate the potential of HZO for transparent devices on substrates with low thermal resistance prepared via the non-heating process.

Automated summary

HZO films prepared via non-heating sputtering are investigated for their application in ferroelectric-gate TFTs. The internal tensile stress induced by ITO top-electrode deposition is found to promote the crystallization of HZO from the amorphous state to the ferroelectric phase. Non-heating process fabricated ITO/HZO/ITO capacitors exhibit ferroelectric hysteresis loops with remanent polarizations of 6-9 μC cm(-2) and coercive fields of 0.6-1.1 MV cm(-1). Non-heating process fabricated ferroelectric-gate TFTs with a 10 nm thick ITO channel show nonvolatile operation with an on/off ratio of ~10.