The extraordinary electronic and optical properties of the crystal-to-amorphous transition in phase-change materials have led to important developments in memory applications. A promising outlook is offered by nanoscaling such phase-change structures. Following this research line, we study the interband optical transmission spectra of nanoscaled GeTe/Sb2Te3 chalcogenide superlattice films. We determine, for films with varying stacking sequence and growth methods, the density and scattering time of the free carriers, and the characteristics of the valence-to-conduction transition. It is found that the free carrier density decreases with increasing GeTe content, for sublayer thicknesses below ∼3 nm. A simple band model analysis suggests that GeTe and Sb2Te3 layers mix, forming a standard GeSbTe alloy buffer layer.We show that it is possible to control the electronic transport properties of the films by properly choosing the deposition layer thickness, and we derive a model for arbitrary film stacks.

Interband characterization and electronic transport control of nanoscaled GeTe/Sb2Te3 superlattices

CARETTA, ANTONIO;CASARIN, BARBARA;PARMIGIANI, FULVIO;MALVESTUTO, MARCO
2016

Abstract

The extraordinary electronic and optical properties of the crystal-to-amorphous transition in phase-change materials have led to important developments in memory applications. A promising outlook is offered by nanoscaling such phase-change structures. Following this research line, we study the interband optical transmission spectra of nanoscaled GeTe/Sb2Te3 chalcogenide superlattice films. We determine, for films with varying stacking sequence and growth methods, the density and scattering time of the free carriers, and the characteristics of the valence-to-conduction transition. It is found that the free carrier density decreases with increasing GeTe content, for sublayer thicknesses below ∼3 nm. A simple band model analysis suggests that GeTe and Sb2Te3 layers mix, forming a standard GeSbTe alloy buffer layer.We show that it is possible to control the electronic transport properties of the films by properly choosing the deposition layer thickness, and we derive a model for arbitrary film stacks.
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.94.045319
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2893369
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