Department of Physics and Materials Science and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong , Tat Chee Avenue, Kowloon, Hong Kong SAR.
ACS Appl Mater Interfaces. 2015 Jan 28;7(3):1699-708. doi: 10.1021/am5072833. Epub 2015 Jan 13.
Tunable charge-trapping behaviors including unipolar charge trapping of one type of charge carrier and ambipolar trapping of both electrons and holes in a complementary manner is highly desirable for low power consumption multibit flash memory design. Here, we adopt a strategy of tuning the Fermi level of reduced graphene oxide (rGO) through self-assembled monolayer (SAM) functionalization and form p-type and n-type doped rGO with a wide range of manipulation on work function. The functionalized rGO can act as charge-trapping layer in ambipolar flash memories, and a dramatic transition of charging behavior from unipolar trapping of electrons to ambipolar trapping and eventually to unipolar trapping of holes was achieved. Adjustable hole/electron injection barriers induce controllable Vth shift in the memory transistor after programming operation. Finally, we transfer the ambipolar memory on flexible substrates and study their charge-trapping properties at various bending cycles. The SAM-functionalized rGO can be a promising candidate for next-generation nonvolatile memories.
对于低功耗多位数闪存设计而言，非常需要可调谐的电荷俘获行为，包括以互补方式对一种类型的电荷载流子（单极电荷俘获）以及电子和空穴（双极俘获）进行俘获。在这里，我们采用通过自组装单分子层（SAM）功能化来调节还原氧化石墨烯（rGO）的费米能级的策略，并通过对功函数进行广泛的操作，形成 p 型和 n 型掺杂 rGO。功能化的 rGO 可以作为双极闪存中的电荷俘获层，并且在充电行为上从电子的单极俘获转变为双极俘获，最终转变为空穴的单极俘获。可调的空穴/电子注入势垒在编程操作后导致存储器晶体管中的 Vth 发生可控的偏移。最后，我们将双极存储器转移到柔性衬底上，并在各种弯曲循环下研究其电荷俘获特性。SAM 功能化的 rGO 可能成为下一代非易失性存储器的有前途的候选材料。
