Ternary CdS_1–xSe_xnanocrystals formed in Cd‐doped As–Se–S films due to photoenhanced diffusion during micro‐Raman measurement

Abstract

Micro‐Raman spectra of amorphous As–Se–S:Cd films prepared by thermal evaporation on silicon and silicate glass substrates measured at different laser power densities show the formation of CdS1–xSex nanocrystals in the As–Se–S:Cd film under laser beam illumination due to a photoinduced material transfer and photoenhanced diffusion in the laser spot area. The material transfer and the photoenhanced diffusion are caused by a non‐thermal interaction of light with the amorphous As–Se–S:Cd films. The chemical composition of the CdS1–xSex nanocrystals can be determined from the difference of the CdSe‐like and CdS‐like LO phonon wavenumbers in the Raman spectra. The photoluminescence peak energies are in agreement with the CdS1–xSex composition, with the average nanocrystal size being somewhat above the exciton Bohr radius.

Raman evidence for the oxidation of amorphous As2(SexS1–x)3 film surfaces under visible light

“…Still, as the latter is less prominent, the relative intensities of the broad maxima near 225 and 340 cm -1 in the spectra of the ternary As-Se-S films correlate with the ratio of Se and S content in the film composition. Such behaviour is in agreement with earlier studies for non-crystalline As-Se-S materials [24,[38][39][40][41]. A more detailed analysis of the Raman features of this amorphous ternary system was performed in our recent study [24].…”

“…Such behaviour is in agreement with earlier studies for non-crystalline As-Se-S materials [24,[38][39][40][41]. A more detailed analysis of the Raman features of this amorphous ternary system was performed in our recent study [24].…”

“…The average surface roughness R a determined from the AFM measurements is within 0.8-1.2 nm (Suplementary Information, table S2). This value slightly varies with the film composition and is in agreement with those obtained from the AFM studies of amorphous arsenic chalcogenide films prepared earlier by a similar technique [13,14,19,24].…”

Photoinduced transformations in (As1–xBix)2S3 glass observed by Raman spectroscopy

“…Partial substitution of arsenic by isovalent antimony or bismuth atoms is expected to result in amorphous ternary (As 1-x Sb x ) 2 S 3 and (As 1-x Bi x ) 2 S 3 compounds similarly to amorphous As 2 (Se x S 1-x ) 3 chalcogenides. 10,11 Antimonydoped As 2 S 3 glasses with Sb content as high as 60-65% were reported, 12,13 while amorphous (As 1-x Bi x ) 2 S 3 materials were fabricated with bismuth content not higher than 4-6 at. %, [14][15][16][17][18] whereas higher Bi concentrations in the mixture resulted in the appearance of crystalline inclusions.…”

“…%, [14][15][16][17][18] whereas higher Bi concentrations in the mixture resulted in the appearance of crystalline inclusions. 17 Among other photostructural phenomena in amorphous arsenic and germanium chalcogenides, 11,[19][20][21] mass transport induced by above-bandgap or belowbandgap illumination has been extensively studied. [22][23][24][25] A drastic photoinduced decrease of the glass viscosity (photofluidisation) is a nonthermal process and leads to an enhanced diffusion in the material, which can result in the formation of a relief on the surface as well as in a rearrangement of atoms in the glass network.…”