Mechanisms and Control of Resistive Switching in Dielectrics

Lead Research Organisation: University of Liverpool
Department Name: Mech, Materials & Aerospace Engineering


So-called "resistive-switching" devices are based on nanostructured dielectric materials, in which the resistance can be varied and memorised. Arguably these devices will lead to a range of disruptive technologies in the field of infromation storage over the next 20 years. Potentially these non-volatile resistive-switching devices can have potentially high speeds, high densities, long retention times and high endurance which will drastically enhance the performance of non-volatile memories and also revolutionise the computer architectures. This research sets out to understand the property - process - structure relationships of oxide dielectrics with programmable resistance. A combination of modelling, synthesis and characterisation will be used to advance the understanding of defects in oxide materials and their control. The aims of the proposed research are to elucidate the nature and mechanisms of the formation and migration of the defects and to explore ways to control and enhance their electrical properties for resistive-switching applications.

The global market for memory devices amounts to more than $57 billion and has been projected to grow to $99 billion by 2015. Within this market, a number of existing memory technologies, (DRAM, SRAM, and NAND Flash) have inherent scaling issues to overcome beyond the next generation. The search for alternative solutions is gaining momentum and an alternative candidate is Resistive RAM which exploits the resistive-switching mechanism. The UK Electronic Systems Community employs more than 850,000 people, which constitutes approximately 3% of the UK workforce. Approximately half of this employment is found in the 30,000 enterprises whose business is overtly the provision of Electronic Systems and the technologies and capabilities they need. The rest are within businesses that occupy market sectors spanning aerospace, defence, healthcare, retail, media and education. The potential impact of this project will be the development of a new manufacturing process technology, which will have applications across these sectors in the UK. The impact in terms of new materials, chemistry, products and processes will be significant if the projeproposed objectives are realised.

Planned Impact

The UK Electronic Systems Community employs more than 850,000 people which constitutes 2.9% of the national workforce. Approximately half of this employment is found in the 30,000 enterprises whose business is overtly the provision of Electronic Systems and the technologies and capabilities they need. The remainder is embedded within businesses that classify themselves by vertical market domains: such as aerospace, defence, healthcare, retail, media and education. Electronic Systems are a vital enabler to their primary product or function to improve functionality, reliability, reduce cost etc. This corresponds to a direct contribution of the order £78 billion (5.4% of UK GDP 2012). This direct contribution corresponds to an indirect one through supply chains, of between 10 to 20 times of that figure, based on an analysis of the EKTN database in 2008.

The proposed research underpins the development of the next generation of non-volatile resistive-switching devices. The potential impact of this research will not only be drastically enhanced performance of non-volatile memories, but will also revolutionize computer architecture. These advances offers a host of new opportunities to system designers, opening up the possibilities for ultra-fast operation with truly persistent data, providing a significant increase in information throughput beyond the traditional benefits of scaling. The technology could also provide nano-sized, programmable multi-level variable resistance for a number of analogue applications including neuromorphic computing system in which its nonlinear dynamics can be used as synapses/neurons, representing a breakthrough for artificial intelligence computing. The pervasive nature of programmeable resistive switching makes its a disruptive technology and if fully realised will have enormous impacts on the worldwide and national ICT industry.


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Chalker P (2016) Photochemical atomic layer deposition and etching in Surface and Coatings Technology

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Maji S (2019) Set compliance current induced resistive memory characteristics of W/Hf/HfOx/TiN devices in Journal of Vacuum Science & Technology B

Description The project has recently finished.. We have demonstratated control of the fundamental conduction mechanisms (through vacancies) in RRAM devices by the use of dopants. The use of nitrogen and fluorine doping in tantalum oxide has been employed to increase the "switching" window between the "on-" and "off-states" of the memory. Through the collaboration with Cambridge and LJMU we have revealed the mechanism for this control, which is through the overall reduction of the O vacancy concentration. This mechanism also explains an increase in the endurance of the devices over time. This "defect engineering" is being developed for new low power and more reliable memory cells.
Exploitation Route These findings to date will be exploitable by RRAM manufacturers, but the big impact will be in the societal benefits of enhanced communications and control systems (e.g. the Internet of Things and mobile computing technology). We are currently seeking to use the outcomes in a further EPSRC application where the devices can be exploited in circuits.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Manufacturing, including Industrial Biotechology

Description The information has been fed back to IMEC through the collaborating partners at LJMU. This has raised new routes to the further development of non-volatile memory materials, which are now being pursued together with Cambridge.
First Year Of Impact 2017
Sector Electronics