MD4Tutorial

This tutorial will introduce the properties of phase-change materials relevant to applications in memory and neuromorphic devices. Part I will discuss the structure-property correlations, including the structural origin of the optical and electronic contrast between the crystalline and amorphous state. Part II will focus on theoretical and computational tools to investigate phase-change materials. In particular, it will review recent ab initio simulations, which have greatly helped to rationalize the structure-property relationship in these materials. Part III will concentrate on experimental methods and discuss recent progress made to optimize the structural, electronic and kinetic properties of phase-change materials.

8:30 am-9:45 am
Part I: Bart Jan Kooi

Part I is an overview of the intimate link between structures and properties of phase-change materials, with the main focus on (1) the differences between amorphous and crystalline phases generating optical and electrical contrast and (2) the extraordinary crystallization kinetics of phase-change materials. Properties will be reviewed mainly with respect to applications in phase-change random access memories, with attention to scaling, data retention and endurance. This segment will demonstrate that memory performance is not only strongly dependent on phase-change material composition, but that for the same phase-change material, it can clearly vary for differently processed memories. Prospective applications of phase-change materials beyond binary data storage will be discussed.

10:15 am-11:30 am
Part II: Jean-Yves Raty

Part II focuses on ab initio simulation techniques and describe how these methods can yield realistic models of phase-change materials. Various quantities that can be obtained from such simulations will be reviewed; these include bonding strength and structural, electronic, optical and dynamical quantities. There will be a discussion of how these quantities can shed light on technologically important features of phase-change materials, such as the optical and electronic contrast between the crystalline and amorphous phase, the stability and the ageing mechanisms of the glass, as well as its crystallization properties at high temperature.

1:30 pm-2:45 pm
Part III: Raffaella Calarco

The third section will review recently developed experimental methods for the realization and growth of crystalline phase change materials and for the optimization of their properties. In addition, it will focus on chalcogenide superlattices and describe a) their peculiar structural and electronic properties and b) various potential applications, ranging from interfacial phase-change memories to novel device concepts based on the topological insulator properties of these superlattices.

Instructors

• Bart Jan Kooi, University of Groningen
• Jean-Yves Raty, University of Liège
• Raffaella Calarco, Paul-Drude-Institut für Festkörperelektronik