Magnetic Electronic Materials and Devices Laboratory

With its great potential to make significant impact in a wide variety of areas ranging from consumer products to industrial equipments, transparent electronics have been considered as an emerging technology for the next generation electronic circuitry and optoelectronic devices. Transparent resistive random access memories (T-RRAMs), carrying the advantages of both invisible electronics and RRAMs, have also attracted tremendous amount of attention from both academic and industrial communities in recent years..

Recently, a research group led by Professor Run-Wei Li fabricated an all-oxide T-RRAM device based on 5 nm hafnium oxide (5nm-HfO_x) storage layer and indium-tin oxide (ITO) electrodes. The memory device demonstrates not only good optical transmittance but also a forming-free bipolar resistive switching behavior with room-temperature R_OFF/R_ON ratio of 45, excellent endurance of ≈ 5×10⁷ cycles and long retention time approaching 10 years.

More importantly, the HfO_x based RRAM carries great ability of anti-thermal shock over a wide temperature range of 10 K to 490 K, and the high R_OFF/R_ON ratio of ≈ 40 can be well maintained under extreme working conditions. The field-induced electrochemical formation and rupture of the robust metal-rich conductive filaments in the mixed-structure hafnium oxide film are found to be responsible for the excellent resistance switching of the T-RRAM devices.

Together with the ultrathin and optically-transparent characteristics, as well as the stable, and anti-thermal shock electrical switching properties of the ITO/HfO_x/ITO sandwich structure, the present mixed-structure HfO_x based all-oxide device renders promising memory capability and optical transmittance for T-RRAM applications.

The research results have been published in Advanced Functional Materials【Volume 24, Issue 15, pages 2171–2179, April 16, 2014】as an inside cover article.