Merging the Sol–Gel Technique with the Pulsed Microplasma Cluster Source Deposition to Improve Control over the Memristive Response of TiO2 Thin Films

Valentina Prusakova,Cristian Collini,Giovanni Giusti,Leandro Lorenzelli,Sandra Dirè,Giancarlo Pepponi,Roberto Verucchi,Mario Barozzi,Salvatore Iannotta

doi:10.3390/coatings11030348

Abstract

Metal oxide thin films show promising resistive switching properties, making them materials of reference for the development of memristive devices. TiO2 is probably one of the most studied materials and is being synthesized using various techniques, each of them having specific optimizable characteristics. In this paper, we report on an innovative approach by combining the sol–gel and the pulsed microplasma cluster source (PMCS) methods, exploiting the low temperature and low cost of the former process and precise control over nanocristallinity of the latter. We show that this approach overcomes the reported limitations that each technique shows in fabricating memristive devices when independently used. A side-by-side comparison of the TiO2 thin films produced by the PMCS, sol–gel, and PMCS/sol–gel hybrid methods (HM) demonstrates an improvement of the memristive properties and a reduction of the electrical shorts in the TiO2 based devices.

Highlights

This paper successfully proposes and demonstrates the hybrid deposition method for developing the TiO2 films combining pulsed microplasma cluster source (PMCS) and sol–gel, two established techniques for metal oxides synthesis in vacuum and wet chemistry, respectively
We showed that these weaknesses can be strengthened or overcome by developing a novel hybrid method merging the sol–gel and the PMCS
(TiO2 P) and the sol–gel (TiO2 S) derived devices to the hybrid TiO2 H, where the PMCS film was deposited on the bottom electrode (BE), and the sol–gel TiO2 was deposited on the top of it

Summary

Introduction

To develop the electrical devices, a detailed insight in the resistive switch is still of demand, and several theoretical studies have been conducted [7,8,9] Driven by this interest, various thin films with a typical thickness of around tens of nm were fabricated by methods where synthesis is achieved by chemical reactions with specific precursors or exploiting direct physical deposition of material in a vacuum. TiO2 thin films were successfully fabricated by atomic layer deposition (ALD) [10,11], reactive magnetron [12], ion beam [13], radio frequency (R.F.) sputtering [14] and laser ablation [15] In addition to these methods, TiO2 thin films were fabricated by the sol–gel approach [16] and metal organic chemical vapor deposition [17]

Methods

Results

Discussion

Conclusion