Spin coated amorphous chalcogenide films: Thermal properties

Abstract

The annealing behavior of spin coated thin films prepared from solutions of As2S3 dissolved in n-propylamine and n-butylamine has been investigated using IR, mass spectrometry, thermogravimetric analysis, and scanning calorimetry. As prepared films containing arsenic sulfide glass domains with surfaces reacted as alkyl ammonium salt undergo loss of amine and hydrogen sulfide during heating. H2S removal is believed to be accompanied by cross linking of glass domains resulting in a network glass containing only arsenic and sulfur.

Structure and properties of spin-coated Ge_25S_75 chalcogenide thin films

“…The most significant organics content loss occurs during the annealing at the temperatures above 120 °C. Chern and Lauks observed similar trend in case of spin-coated As2S3 thin films, but at lower annealing temperature (80 °C) [13]. They proposed that organic molecules bonded in form of alkyl ammonium arsenic sulfide (AAAS) salts start to decompose at 80 °C and further increase of annealing temperature supports decomposition process.…”

“…Observed increase could be explained by increasing compactness of the film (densification). According to [13] the freshly prepared spin-coated thin films of As-S system consist of glass clusters separated by voids and organic molecules used in the solution. The organic molecules are ionically bonded to the ChG clusters in form of alkyl ammonium chalcogenide salt.…”

“…Major disadvantage of solution based deposition methods are the residual amount of solvent remaining in the thin film's structure. But its content can be significantly lowered by proper annealing [12,13,16].…”

“…Thin films deposited by solution based techniques have been widely studied on arsenicbased ChGs [12][13][14][15][16][17], which limits their wide-spread application due to the arsenic toxicity. Germanium-based spin-coated thin films of Ge23Sb7S70 glass composition were successfully prepared [20], but further study of other germanium-based systems is needed to obtain plurality of different non-toxic optical materials prepared by solution based deposition techniques.…”

“…Spincoating and dip-coating deposition methods are frequently used for ChG thin films deposition [12][13][14][15][16][17], but these techniques are suitable only for basic material research and small scale production. Well known and managed printing [18] and coating [19] techniques allowing continuous deposition are gaining attention for large scale production purposes.…”