Integration of Novel Materials in Spintronic Devices

Lead Research Organisation: University of Cambridge
Department Name: Engineering

Abstract

The continued scaling of charge-based computing devices is reaching its limits and, both for more Moore (continued scaling) and more than Moore (functional diversification), the International Semiconductor Roadmap is looking at new materials and their integration in existing manufacturing technology. Two dimensional (2D) materials, such as graphene, exhibit unique electrical, thermal and mechanical properties and show promise as components for a wide range of device applications, in particular spintronics and next generation micro/optoelectronics and systems. Graphene can not only support very high carrier mobilities and current densities, but also has small spin-orbit coupling and large electron coherence length. Also, due to its atomic thickness, it is very interesting for tunnel junction device architectures. With hundreds of millions of computer hard drives sold every year, magnetism is currently the main repository of information storage. It is the electron "spin," the elementary nanomagnet, that carries the information. Beyond storage, spintronics and such new device architectures are foreseen as the foundation for a new paradigm for information processing toward low-power-consumption nonvolatile "green" electronics.
This proposal aims at creating an international research network to develop new integrated electronic and spin-based device concepts based on 2D materials, to overcome key experimental problems such as controlled interfacing and to develop integrated manufacturing technology, which would allow 2D materials to enter the semiconductor roadmap, the key to unlocking their commercial potential. The proposal thereby combines the world leading expertise of the international partners, in particular on the development and manufacture of state-of-the-art semiconductor devices of the Japanese Partners, on 2D manufacturing technology and device material know-how of the UK partners and the spintronics expertise of the French partners. The proposed research has a strong industrial alignment, paving the way for realistic routes to markets for these new materials and device architectures.

Planned Impact

The project addresses key questions relevant to industrial materials development of 2D materials, in particular their integrated manufacturing. The proposed collaboration builds on UK's track-record in carbon-based materials to make a significant impact on the area more globally, academically as well as industrially. These advanced materials and the proposed devices are areas of national importance to the UK and a key part of the EPSRC funding portfolio in particular fully in line with a number of EPSRC's emerging areas incl. the convergence of spintronics with very-large-scale-integrated-circuits.
The market for these 2D materials and all commercialisation strategies are currently limited by a lack of scalable manufacturing pathways, in particular regarding applications in the lucrative high-tech market. Hence the proposed research programme is highly relevant to the academic research relating to graphene and other 2D materials and crucial to increase the industrial relevance of these advanced materials, and to enable commercial dividends to be paid on the substantial investment that the UK (and other partner countries) has already made in graphene research, and which it will make in the future.
The project has a strong industrial alignment including a large number of existing world-wide industrial partners of the consortium. For the Cambridge team, the proposal links closely to existing EPSRC funding in particular the Graphene Centre and the grant GRAPHTED (EP/K016636/1) as well as the doctoral training centres on Nano and Graphene. The proposed international research network will significantly increase also the impact of this existing EPSRC funding. We infer that the technology IP created will yield long-term economic benefits to the UK, which will accrue as capability grows.
The long term societal impact of our project can be significant in particular through the proposed breakthrough technology for the next generation semiconductor devices. Over the last 60 years the progress in the semiconductor industry has revolutionised our society, bringing it into the Digital Age, and further progress in this technology which our programme focuses on will help to continue progressing our knowledge-based society surrounded by a high-tech global economy.

Publications

10 25 50
 
Description Magnetic tunnel junctions (MTJs) are key components within magnetic storage devices such as hard disk drives. We have realised that a layered material, hexagonal boron nitride (h-BN) could be a good tunnel barrier layer instead of the presently used crystalline MgO. We know so far that h-BN is an excellent diffusion barrier (which MgO is not). and we are trying to see whether h-BN will have the tunnel selectivity that is possible with MgO.

Our group have been very successful in growing h-BN films, and with partner CNRS doing the measurements, they have shown it has very valuable spin transport characteristics. These have resulted in strong publications.

The Japanese partner Prof T Endoh of Tohoku University has been running an industrially oriented program to apply STT-MRAM and its performance has resulted in it moving up from the ~5th memory technology (because it contains many layers) to the 2nd (because of its endurance and reliability. It has resulted in key collaborations with major electronics groups, Intel, TSMC etc.
Exploitation Route Used in electronic devices.
Sectors Digital/Communication/Information Technologies (including Software),Electronics,Transport

URL http://www.material.tohoku.ac.jp/~kotaib/CCPGRIEC/CCPGRIECHP/invited.html
 
Description The use of h-BN for tunnel barriers in magnetic tunnel barriers could have valuable technical uses. High impact paper have been published with our French partners. Some high impact papers are in preparation with the Japanese partner. The industrial impact of the memory technology STT-MRAM has grown over the period of the project.
First Year Of Impact 2016
Sector Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Economic

 
Title Data supporting "Enhancing Photoluminescence and Mobilities in WS2 Monolayers with Oleic Acid Ligands" 
Description The data presented supports the results shown in the article. Origin file contains folders for data sets representing each figure in publication. Each folder can be accessed via the Project Explorer. Each folder is named according to the data it contains. The first folder (Fig 1a-d, Fig.3 SI) contains photoluminescence (PL) statistics of chemically treated tungsten disulphide (WS2) and WS2 monolayer absorption spectra respectively. The second folder (Fig 2.a.-f, Fig 2a-d, Fig 6 SI) contains steady-state PL excitation series, trion emission characterization, and PL spectra of oleic acid (OA) treated WS2 on different substrates respectively. The third folder (Fig. 3a-b, Fig 4a-d SI) contains time-resolved PL data for pristine, Oleic acid and TFSI treated WS2 at the lowest laser fluence with variation in fast decay component with carrier concentration (Fig 3a-b); time-resolved PL data for all treatments with variation in slow decay component with initial carrier concentration (SI Fig 4a-d). The fourth folder (Fig 4a and SI Fig 5) contains Raman spectra of OA treated WS2 and the effect of toluene on WS2 monolayer PL. The fifth folder (Fig 4b) contains transfer characteristics of a gated WS2 transistor. The sixth folder (Fig 4c) contains the transfer characteristics of a gated WS2 transistor with detail on the difference in gradient between OA treated and untreated WS2. The seventh folder (Fig 1 SI) shows the raw excitation series PL data fitted with Gaussian curves for OA treated WS2, which were used in characterizing trion emission seen in SI figure 2. The eighth folder (Fig 7 SI) contains transfer characteristics for a TFSI treated transistor 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes