Role of sweep direction and substrate work function on resistive switching of titanium-di-oxide [TiO2] nanoparticles

The resistive switching mechanism in titanium-dioxide nanoparticles (TiO2 NP) is studied using the currentvoltage (I-V) measurements. The TiO2 NP are spin-coated on different substrates like FTO, ITO, Gold, and p-Silicon. The I-V measurements are carried out by changing the initial potential of the substrates to either 0 V (sweep1) or -1 V (sweep2). Resistive switching (RS) was observed only for FTO/TiO2 NP and ITO/TiO2NP devices in sweep1 direction. Whereas, in sweep2 direction, no such RS was observed in any of the devices. The detailed I-V analysis infers the Ohmic conduction followed by space charge limited conduction (SCLC) during the RS forming process for FTO/TiO2 NP and ITO/TiO2NP devices. The Au and p-Si substrates act as blocking contact for TiO2 and exhibit Schottky/thermionic emission at lower voltages and SCLC at higher voltages. The TiO2 NP coated on p-Si substrate exhibits rectifying behaviour with a current ratio of 3 orders of magnitude.