Photoinduced effect in Ga–Ge–S based thin films

Surface morphology of as-deposited and illuminated As–Se chalcogenide thin films

“…The experimental set-up for this study is well described in literature (see, e.g. [20]) and these experiments will be detailed later.…”

Aging process of photosensitive chalcogenide films deposited by electron beam deposition

“…While the mechanism of photooxidation of chalcogenides is still under discussion, previous works [46][47][48][49][50][51] suggest that photo-induced changes may be due to incorporation of oxygen in the glass matrix and to formation of covalent bonds with glass-forming elements, e.g. Ge-O or Ge-OH bonds at the surface in the case of Ge-Sb-S films.…”

Oxygen assisted photoinduced changes in Ge39Ga2S59 amorphous thin film

“…(d) The thickness of the film illuminated in air increases approximately two times (by about 40 nm), see Table 2 in comparison with the thickness increase (by about 20 nm) of the film illuminated by UV photons in the dry nitrogen atmosphere. This result to a certain extent seems to be reminiscent of the giant photoexpansion (up to 1.7 μm on the film with a thickness around 4 μm) induced due to photooxidation (UV laser, 350 nm) of the Ga 10 Ge 25 S 65 amorphous film [3]. (e) The protuberances were created by UV photons even if the illuminated film was sandwiched between the film substrate and the sealed quartz plate (msh) and the whole system inclusive aperture space was blown-through by dry nitrogen before illumination (60 min) and during illumination, Fig.…”

“…For photoexpansion in Ge-S binary glasses, the presence of Ga atoms is suggested to be essential because just photooxidation leads to formation of (Ge/Ga)-O units inducing photoexpansion [8]. From a number of studies it is evident that (i) the blue light supports photooxidation of amorphous chalcogenide films and (ii) photooxidation of amorphous chalcogenides is an interesting process which could significantly and dynamically modify the surface, near surface states and even, depending on the actual conditions of photooxidation, the volume properties of the films [3][4][5][6][7][8]. Moreover, it seems that compositional and structural changes associated with photooxidation "can be applied to in situ formation of materials with a new structural organization" [7].…”

“…Recently attention was renewed to the role of oxygen in photoinduced changes in binary and ternary amorphous chalcogenides containing germanium atoms. For instance, in some Ge-Ga-S amorphous films exposed by UV laser (350 nm) photobleaching and photoexpansion were attributed to photooxidation [3]. An oxidation of the surface of Ge-As-S amorphous films was observed using X-ray photoelectron spectroscopy of the samples illuminated by Mercury lamp [4].…”