Graphene/ferroelectric hybrid devices (Vol. 42, No. 2)

image The figure shows the device operations of GFeFETs on PZT (Fig. a) with different local ferroelectric polarization magnitude. In the linear regime of PZT (Fig. b), ultra-low-voltage operation of graphene field effect transistors within +/-1 V with maximum doping exceeding 1013 cm-2 and on-off ratios larger than 10 times is demonstrated. After polarizing PZT (Fig. c), switching of graphene field effect transistors are characterized by pronounced resistance hysteresis, suitable for ultra-fast non-volatile electronics.

The soaring demands on non-volatile memory for ultra-portable electronic devices have grown NAND flash into a multi-billion dollar business. As a Si-CMOS based technology, NAND flash provides the most aggressive scalability, closely following the-state-of-art semiconductor manufacturing process. NAND flash also takes advantage of its relatively simple floating-gate structure and seamless integration with Si-CMOS logics, leading to significant lower production cost over other competing non-volatile technologies such as FeRAM and MRAM.

Graphene, with its ultra-high mobility and almost unlimited scalability down to atomic scale, is considered now as one of the most promising candidates for replacing Si. Graphene-based non-volatile memory has also been demonstrated very recently. However, a seamless solution for integrating graphene transistors and non-volatile memory remains a challenge.

Here, Zheng et al. demonstrate the wafer-scale patterning and device operations of Cu-CVD graphene-ferroelectric field effect transistors (GFeFETs) on ferroelectric Pb(Zr0.3Ti0.7)O3 (PZT) substrates, integrating both transistor and non-volatile memory functionalities on the same chip.

In the linear regime of PZT, ultra-low-voltage operations of GFeFETs within +/-1V can be used as controlling transistors for addressing and reading/writing of memory unit cells. After polarizing PZT, the hysteretic switching of GFeFETs is ideal for ultra-fast non-volatile data storage. The combination of high-quality Cu-CVD graphene and functional substrates will not only greatly speed up the studies of all graphene-based electronics but also open up a new route in exploring new graphene physics and functionalities.

Wafer-scale graphene/ferroelectric hybrid devices for low-voltage electronics
Yi Zheng, Guang-Xin Ni, Sukang Bae, Chun-Xiao Cong, Orhan Kahya, Chee-Tat Toh, Hye Ri Kim, Danho Im, Ting Yu, Jong Hyun Ahn, Byung Hee Hong and Barbaros Özyilmaz, EPL, 93, 17002 (2011)
[Abstract] | [PDF]