Amorphous Ge-Bi-Se Thin Films: A Mass Spectrometric Study

Ravi Mawale,Petr Němec,Jan Gutwirth,Govinda Mandal,Marek Bouška,Pankaj Lochan Bora,Josef Havel,Virginie Nazabal

doi:10.1038/s41598-019-55773-9

Abstract

The Ge-Bi-Se thin films of varied compositions (Ge content 0–32.1 at. %, Bi content 0–45.7 at. %, Se content 54.3–67.9 at. %) have been prepared by rf magnetron (co)-sputtering technique. The present study was undertaken in order to investigate the clusters generated during the interaction of laser pulses with Ge-Bi-Se thin films using laser ablation time-of-flight mass spectrometry. The stoichiometry of the clusters was determined in order to understand the individual species present in the plasma plume. Laser ablation of Ge-Bi-Se thin films accompanied by ionization produces about 20 positively and/or negatively charged unary, binary and ternary (Gex+, Biy+, Sez+/−, GexSez+/−, BiySez+/− and GexBiySez−) clusters. Furthermore, we performed the laser ablation experiments of Ge:Bi:Se elemental mixtures and the results were compared with laser ablation time-of-flight mass spectrometry analysis of thin films. Moreover, to understand the geometry of the generated clusters, we calculated structures of some selected binary and ternary clusters using density functional theory. The generated clusters and their calculated possible geometries can give important structural information, as well as help to understand the processes present in the plasma processes exploited for thin films deposition.

Highlights

Amorphous chalcogenides have received great attention due to their unique properties and a broad range of applications
Physical properties of binary or ternary chalcogenide glasses based on the Ge-Se system can be further adjusted by adding other elements
The elemental composition of the fabricated thin films was obtained by EDS at different spots of the films and averaged (Table 1)

Summary

Introduction

Amorphous chalcogenides have received great attention due to their unique properties and a broad range of applications. Chalcogenide compounds have emerged as multipurpose material and have been used for various applications for solid-state devices[1] Due to their specific properties, chalcogenide glasses and their amorphous thin films are applied in photonics[2], solar cells[3], phase change memories[4,5], optical fibers[6], etc. Amorphous Ge-Bi-Se chalcogenide thin films are investigated to study their optical and electrical properties[17,18,19], structure[17,20,21], etc. Se via laser ablation processes, as confirmed through time-of-flight mass spectrometry This technique can be used to elucidate the structural fragments present in the plasma generated during the interaction of high energy laser pulses with chalcogenide glasses[25,26,27]. Mass spectrometric study of Ge-Bi-Se materials has not yet been reported, and it is carried out here

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