Phase - change Sn - Se thin films propared via pulsed laser deposition.

Abstract

Sn-Se phase-change thin films with four different nominal compositions (Sn40Se60, Sn37Se63, Sn33Se67, Sn30Se70) were prepared by UV pulsed laser deposition. Fabricated films were investigated in the context of the structure, optical and electrical behaviour in both, as-deposited (amorphous) and annealed (crystalline) state. The samples exhibit good electrical contrast between amorphous and annealed state (approx. 3-6 orders of magnitude) and the optical contrast |Delta n|+|Delta k| for the wavelength 405 nm/780 nm is about 0.84/1.75 respectively. The study of the Sn-Se films revealed that compositions are prone to undergo phase change into crystalline SnSe and SnSe2 and display unusual electrical behaviour upon heating. This phenomenon may be characterized as the "localization of electrical charge" occurring very likely on the clusters of nanoparticles of either p-type or n-type crystallized phase.