Some optical properties of Ge–S amorphous thin films

Oxygen assisted photoinduced changes in Ge39Ga2S59 amorphous thin film

“…The blue shift of the optical band gap seen in all cases indicates bleaching of the films after a treatment. The maximum band gap shift is observed for annealing, a moderate shift is observed for illumination by UV photons and in compliance with literature data [9], only the over gap photons ( hω ph = 2.48 eV) with d p comparable to the film thickness induce the small blue shift of the gap. The slope of SWAE increases after annealing, which is a sign to film matrix ordering.…”

“…1, are reminiscent of our former results [9,23]. We suppose that in the Ge 39 Ga 2 S 59 thin film similarly as in the case of the Ge 40 S 60 amorphous film [9], the rigidity of the matrix assists to a weak photosensitivity of the studied film. Consequently, attention is paid to Fig.…”

“…The overall light intensity in this case was around 1.24 Wcm −2 and the time of illumination was 25 min. The illuminations (i) and (ii) were performed in a sample holder which allowed for protection of the sample surface against any photoinduced oxidation and also for the reduction of the light induced overheating by a continuous flow of nitrogen around the sample surface [9]. (iii) We realized also illumination of the virgin film by UV photons in a modified sample holder (msh).…”

Kinetics of self-bleaching in some photodarkened Ge–As–S amorphous thin films

“…3 in [17], represents very weakly stressed-rigid network. Such network allows propagation of light induced structural change and its conservation because the network rigidity (CN = 2.5 > 2.45, [19]) is 'reasonable weak'. We suppose that just the differences in the networks of Sa 1 and Sa 3 films are reflected in differences in magnitude of photodarkening (dE g,SD(1)ÀA ) and in the way of relaxation (self-bleaching) of photodarkened state Sa 1 and Sa 3 films.…”

“…Annealed films were illuminated up to saturated photodarkened state using monochromatic light with the energy (⁄x ph ) corresponding to the optical gap of respective annealed film. Illumination was carried out in a special sample holder [19], which enabled to protect the sample surface against photoinduced oxidation and also allowed to minimize possible light induced overheating of the sample by a continuous flow of dry nitrogen around the sample surface. The penetration depth of the light was comparable to the film thickness (1.3-1.5 lm) and the photon flux of incident light was %410 17 cm À2 s À1 ±10%.…”