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

We propose a novel metal/silicon/metal (MSM) selector using ultrathin undoped amorphous silicon (a-Si) for resistive-RAM selector application. The new selector behaves as a bidirectional diode, showing a high current drive (~2.2 MA/cm)2, high selectivity (~240 for 1/2 bias), fast switching speed , and excellent endurance ( 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 HfO2-based resistive switching memory element.