Ultrathin Metal/Amorphous-Silicon/Metal Diode for Bipolar RRAM Selector Applications

摘要

We propose a novel metal/silicon/metal (MSM) selector using ultrathin $({<}{rm 10}~{rm nm})$ undoped amorphous silicon (a-Si) for resistive-RAM selector application. The new selector behaves as a bidirectional diode, showing a high current drive $({sim}{rm 2.2}~{rm MA}/{rm cm})^{2}$, high selectivity (${sim}{240}$ for 1/2 bias), fast switching speed $(<{rm 1}~{rm ns})$, and excellent endurance (${>}{rm 10}^{8}~{rm cycles}$ at target drive current). The doping-free a-Si structure alleviates the dopant-induced variability concerns for ultrascaled devices and eliminates the need for a dopant-activation anneal. Circuit simulations show feasibility of 1-Mb array, with over 25% read margin and 70% write margin, when using the new MSM structure as a selector for a ${rm HfO}_{2}$-based resistive switching memory element.