Test-photostability of pulsed laser deposited amorphous thin films from Ge-As-Te system

Tailoring of Multisource Deposition Conditions towards Required Chemical Composition of Thin Films

The model to tailor the required chemical composition of thin films fabricated via multisource deposition, exploiting basic physicochemical constants of source materials, is developed. The model is experimentally verified for the two-source depositions of chalcogenide thin films from Ga–Sb–Te system (tie-lines GaSb–GaTe and GaSb–Te). The thin films are deposited by radiofrequency magnetron sputtering using GaSb, GaTe, and Te targets. Prepared thin films are characterized by means of energy dispersive X-ray analysis coupled with a scanning electron microscope to determine the chemical composition and by variable angle spectroscopic ellipsometry to establish film thickness. Good agreement between results of calculations and experimentally determined compositions of the co-deposited thin films is achieved for both the above-mentioned tie-lines. Moreover, in spite of all the applied simplifications, the proposed model is robust to be generally used for studies where the influence of thin film composition on their properties is investigated.

Synthesis and Application of Monomeric Chalcogenolates of 13 Group Elements

Utilization of the N,C,N-chelating ligand L (L={2,6-(Me₂ NCH₂ )₂ C₆ H₃ }^- ) in the chemistry of 13 group elements provided either N→In coordinated monomeric chalcogenides LIn(μ-E₄ ) (E=S, Se) with unprecedented InE₄ inorganic ring or monomeric chalcogenolates LM(EPh)₂ (M=Ga, In). Complex LGa(SePh)₂ was selected as the most suitable single source precursor (SSP) for the deposition of amorphous semiconducting GaSe thin films using spin coating method.

Photostability of pulsed-laser-deposited AsxTe100-x (x=40, 50, 60) amorphous thin films

As_xTe_100-x amorphous thin films were fabricated by a pulsed laser deposition technique with the aim of finding photostable layers in as-deposited but preferably in relaxed (annealed) state. Photostability was studied in terms of the films' stability of refractive index and bandgap under near-bandgap light irradiation. As₄₀Te₆₀ and As₅₀Te₅₀ layers were found to be photostable in both as-deposited as well as relaxed states. Moreover, As₅₀Te₅₀ layers present the lowest surface roughness. These characteristics make pulsed-laser-deposited As₅₀Te₅₀ thin films promising for applications in nonlinear optics.

Pulsed laser deposited GeTe-rich GeTe-Sb2Te3 thin films

Pulsed laser deposition technique was used for the fabrication of Ge-Te rich GeTe-Sb2Te3 (Ge6Sb2Te9, Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15) amorphous thin films. To evaluate the influence of GeTe content in the deposited films on physico-chemical properties of the GST materials, scanning electron microscopy with energy-dispersive X-ray analysis, X-ray diffraction and reflectometry, atomic force microscopy, Raman scattering spectroscopy, optical reflectivity, and sheet resistance temperature dependences as well as variable angle spectroscopic ellipsometry measurements were used to characterize as-deposited (amorphous) and annealed (crystalline) layers. Upon crystallization, optical functions and electrical resistance of the films change drastically, leading to large optical and electrical contrast between amorphous and crystalline phases. Large changes of optical/electrical properties are accompanied by the variations of thickness, density, and roughness of the films due to crystallization. Reflectivity contrast as high as ~0.21 at 405 nm was calculated for Ge8Sb2Te11, Ge10Sb2Te13, and Ge12Sb2Te15 layers.