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The University of Southampton
Advanced Composite Materials Facility

Phase change memory for memory applications

Chalcogenide materials for data storage applications, both for optical storage media or the next generation of RAM and Flash® memory applications, rely on the thermally induced phase change between the amorphous and polycrystalline state in a small volume of the material.

Characterisation of the basic amorphous to crystalline phase change in new ternary or quaternary materials is a prerequisite for the further screening and optimisation of the material for the various storage configurations. The ACMF has developed high throughput methods for the primary screening of phase change materials, demonstrating the workflow using the benchmark GeSbTe ternary alloy system, which has been extensively used in the industry.

The amorphous to crystalline phase transition for the GeSbTe thin film library measured by HTOMPT heating between room temperature and 400°C: a) the temperature of crystallisation Tc and b) the change
The amorphous to crystalline phase transition for the GeSbTe thin film

Compositional gradient thin film materials library

We have applied our evaporative high-throughput physical deposition (HT-PVD) method to produce compositional gradient thin film libraries of the amorphous alloy system. We have developed a new primary screening methodology HTOMPT (High Throughput Optical Mapping of Phase Transition) which provides the parallel determination of the crystallisation temperature and the optical change in reflectivity of the library.

The ternary compositional map of the electrical resistance contrast associated with the amorphous (as deposited) to crystalline (at 300C) phase transition for a GeSbTe thin film library
The GeSbTe ternary compositional map of the electrical resistance.

Combined with a primary screening of the electrical contrast associated with crystallization, and full primary compositional (EDX) and structural (XRD) characterization, we demonstrate a rapid method for the preliminary optimization of materials for potential application in RAM.

We are now investigating novel materials for phase change memory applications including a range of sulphur based chalcogenide materials.

Publications:

Guerin, S., Hayden, B., Hewak, D.W., Purdy, G. and Simpson, R.(2005)

High throughput synthesis and screening of chalcogenide materials for data storage.

In, Singapore International Chemistry Conference 4, Singapore08 - 10 Dec 2005. ,

 

Guerin, S., Hayden, B., Hewak, D.W., Purdy, G. and Simpson, R.E.(2005)

Combinatorial synthesis and screening of chalcogenide materials for data storage.

In, PCOS 17th Symposium, Japan17 - 18 Nov 2005., 6 pp.

 

Guerin S., Hassan M., Hayden B.E., Hewak, D.W., Purdy G., and Simpson R. E. (2005)

Material optimisation for optical data storage.

In, Frontiers in Optics 2005 and Laser Science XXI: The 89th OSA Annual Meeting, Arizona, USA16 - 20 Oct 2005.Tucson, USA, Optical Society of America, 1pp.

 

Simpson, R.E., Hewak, D.W., Guerin, S., Hayden, B. and Purdy, G. (2005)

High throughput synthesis and screening of chalcogenide materials for data storage.

In, EPCOS-O5 European Symosium on Phase Change and Ovonic Science, Cambridge, UK05 - 06 Sep 2005.

 

R E Simpson P J Fons M Kuwahara A Kolobov and J Tominaga, D W Hewak S Guerin and B E Hayden

Reduction in crystallization time of Sb:Te films through addition of Bi

In, EPCOS-O8 European Symosium on Phase Change and Ovonic Science, Prague - 2008.

 

D.W.Hewak, C.C.Huang, B.Gholipour and K.Knight, S.Guerin, B.Hayden and G.Purdy

Thermally stalble low current consuming gallium and germanium chalcogenides for consumer and automotive memory applications

In, EPCOS-11 European Symosium on Phase Change and Ovonic Science, Zurich 4-6 Sep (2011)

 

Gholipour, B., Zhang, J., Al-Saab, F., MacDonald, K.F., Hayden, B.E., Hewak, D.W., Zheludev, N.I.

Chalcogenide glass photonics: non-volatile, bi-directional, all-optical switching in phase-change metamaterials

In, Conference on Lasers and Electro-Optics (CLEO), 6-11 May 2012, San Jose, CA, USA, IEEE Photonics Soc.

 

Brian E. Hayden

Reduction in crystallization time of Sb:Te films through addition of Bi - Simpson, R.E., Hewak, D.W., Fons, P., Tominaga, J., Guerin, S. and

Applied Physics Letters 92 (2008) 141921 doi:10.1063/1.2901161

 

Brian E. Hayden

The Discovery and Optimisation of Solid State Materials for the Energy and the Electronics Sectors using MBE Based Methodologies

NSTI-Nanotech 3(2012) 571-574

ISBN: 978-1-4665-6276-9

 

Samuel Guerin, Brian E. Hayden*, Dan W Hewak and Christopher Vian

ACS Combinatorial Science (to be submitted 2016).

 

Funding and Support

Ilika Technologies Ltd

EPSRC The Chalcogenide Advanced Manufacturing Partnership

 

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