Biju, Kuyyadi P.Liu, XinjunKim, SeonghyunJung, SeungjaePark, JubongHwang, Hyunsang2015-12-081862-6254http://hdl.handle.net/1885/37946Reversible clockwise and counter-clockwise resistive switching in a Pt/graded WOx /W stack is reported. Two stable switching modes with opposite switching polarity and different electrical characteristics are found to coexist in the same memory cell. Clockwise switching shows filamentary characteristics that lead to relatively faster switching with excellent retention at high temperature. Counter-clockwise switching exhibits homogeneous conduction with slower switching and moderate retention. The field-induced switching reversal might be due to inhomogeneous expansion of W during thermal oxidation. Our results provide a clue to modulate the switching type in Pt/WOx /W memory cells. (Keywords: Counter-clockwise; Electrical characteristic; Filamentary switching; Graded WO x ; High temperature; Homogeneous switching; Memory cell; Memory performance; Resistive switching; Reversible effects; Switching modes; Thermal oxidation; Semiconducto Filamentary switching; Graded WOx; Homogeneous switching; Resistive switching; Switching polarity201110.1002/pssr.2010044552016-02-24