Mixed-Phase TiO<sub>2</sub> Nanotube–Nanorod Hybrid Arrays for Memory-Based Resistive Switching Devices
Priyanka Bamola, Bharti Singh, Aranya Bhoumik, Mohit Sharma, Charu Dwivedi, Mandeep Singh, Goutam Kumar Dalapati, Himani Sharma
Abstract
Metal oxide nanostructure hybrid materials have garnered focused attention for next-generation memory-based devices. TiO2 nanostructure hybrids dwell in that league of materials. In reference to that, the present work reports the growth of mixed-phase TiO2 nanostructures (MxPh-TNs) and their hybrids by grafting metal nanoparticles (MNPs). MxPh-TNs are a concoction of rutile nanorods and anatase nanotubes, imaged using field-emission scanning electron microscope and further confirmed by micro-Raman spectroscopy. During the growth of MxPh-TNs, a rutile and anatase mixed-phase interface is formed, as confirmed by high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. Furthermore, by grafting MNPs of platinum (Pt) and palladium–platinum (Pd–Pt) over MxPh-TNs, a top interface is investigated in order to have modifications in their structure and electronic interaction. Thus, dual interfaces corresponding to a mixed phase (rutile and anatase) and MNPs/TNs result in the modification of formed nanostructures and their hybrids (MX-TNHs), as confirmed by X-ray photoelectron spectroscopy and Kelvin probe force microscopy (KPFM) studies. Modification at the interface results in improved crystallinity and symmetric barriers for charge transport in hybrid structures. MxPh-TNs and MX-TNHs are further explored for device applications in the form of memristive resistive switching devices. It is observed that the device performances of Pt/MX-TNHs and Pd–Pt/MX-TNHs are better than that of MxPh-TNs in terms of the memory window (ION/IOFF ratio). The improved device performance in the hybrid structures are due to the enhanced charge separation and defects at the interface of MNPs (Pt and Pd–Pt) and MxPh-TNs.