ALD Heterojunction Ovonic Threshold Switches
Valerio Adinolfi, Mario Laudato, Ryan Clarke, Scott Jewhurst, Martin E. McBriarty, Son Hoang, V. Narasimhan, Lanxia Cheng, Karl A. Littau
Abstract
Conformal atomic layer deposition (ALD) of chalcogenide films would enable aggressive 3D integration of nonvolatile memories; unfortunately, the fabrication of high-performance ALD OTSs remains an unsolved problem. Here we present an ALD process to incorporate As in a quaternary GeAsSeTe (GAST) film showing excellent conformality, controllable thickness, and composition homogeneity. The films were used to produce a GeSe/GAST heterojunction-OTS selector. We demonstrate low leakage current (∼10–9 A over a 0.01 μm2 area measured at VTH/2), a VTH ∼ 3 V, a switching time of ∼2 ns—and an outstanding endurance exceeding 109 cycles—on par with the current OTS state-of-the-art.