Raman Scattering in Amorphous Selenium Molecular Structure and Photoinduced Crystallization

Abstract

Raman scattering measurements are reported for amorphous selenium. It is found that the molecular structure of a-Se on the scale of medium-range order differs from the structure of most inorganic glasses. A laser-induced glass-crystalline transition is also studied. The experimental results suggest the existence of successive phases in such transition with pronounced threshold behaviour.

Oxidation dynamics of ultrathin GaSe probed through Raman spectroscopy

“…The first at 130 cm −1 likely corresponds to SeO 2 or SeO 3 Raman modes 36,37 , but a quantitative analysis of this feature has proven difficult; it will not be further discussed. The other feature at 257 cm −1 matches the characteristics of a mode associated to selenium 26,38 and its width (∼20 cm −1 ) suggests an amorphous phase (a-Se) 39,40 . The narrower peak (∼5 cm −1 ) at 241 cm −1 appears last and is associated 41 to a selenium crystalline phase (c-Se).…”

Photo-crystallization in a-Se imaging targets: Raman studies of competing effects

“…Raman scattering has been utilized effectively by a number of researchers to study photo-induced crystallization in a-Se and other chalcogenide-based glasses [12,[22][23][24][25][26]. The Raman spectrum of a-Se is dominated by a broad band with maximum near 250 cm À1 ($20 cm À1 FWHM), due to the A 1 -symmetry bondstretching vibrations of the chain fragments and ring-like units that comprise the amorphous Se structure [22,27,28].…”

“…The Raman spectrum of a-Se is dominated by a broad band with maximum near 250 cm À1 ($20 cm À1 FWHM), due to the A 1 -symmetry bondstretching vibrations of the chain fragments and ring-like units that comprise the amorphous Se structure [22,27,28]. The ringfraction is often found to be small in well-annealed samples [12,25,29]. During photo-crystallization, a low-frequency shoulder develops on this band near 235 cm À1 consisting of two sharp peaks at $233 cm À1 and $237 cm À1 (often unresolved).…”

“…During photo-crystallization, a low-frequency shoulder develops on this band near 235 cm À1 consisting of two sharp peaks at $233 cm À1 and $237 cm À1 (often unresolved). These peaks grow in strength while the initial 250 cm À1 a-Se feature weakens [12,25]. The two sharp peaks are due, respectively, to the E-and A 1 -symmetry bond-stretching optical modes of trigonal Se, down-shifted by inter-chain interactions in the crystal from the corresponding frequencies in a-Se [27,30].…”

Characterizations of a-Se based photodetectors using X-ray photoelectron spectroscopy and Raman spectroscopy

“…However, when the device is used for hours continuously, the performance was found to deteriorate largely due to the degradation of the a-Se target as mentioned in the literature. There are many optical studies of chalcogenide glasses in order to understand crystallographic characteristics, including those associated with phase transition [8][9][10][11][12], but as far as the authors know, there are hardly any reports focusing on utilizing a-Se films for photoelectric conversion devices.…”