Thermographic analysis of localized conductive channels in bipolar resistive switching devices

Temperature distributions in Pt/SrZrO3/SrRuO3 and Pt/TiO2/Pt thin film heterostructures were imaged by infrared thermography while under electrical bias. Local hot spots with lateral sizes between 5 and 30 mu m appear during electroforming, they reappear during switching, and they show temperature increases from 50 to above 250 degrees C. Over 90% of conductivity increases produced by electroforming were confined to the hotspot locations. In some structures, thermography demonstrated that two separate conductive paths could be formed using opposite biases, and their conductivities could be repeatedly switched on and off with opposite voltage dependences. Direct evidence of large temperature increases supports the existence of Joule heating within the conductive channel during resistance switching of oxide heterostructures.