Defect configurations in Ge–S chalcogenide glasses studied by Raman scattering and positron annihilation technique

Surface of glassyGeS2: A model based on a first-principles approach

“…The analysis of the WF centers with respect to the nuclear positions allows gaining insight into the chemical bonding involved in systems such as water [50][51][52], amorphous silicon [53], and oxides [54]. This analysis has been extended to germanium selenides g-Ge 2 Se 3 , g-GeSe 2 , g-GeSe 3 , g-GeSe 4 , and g-GeSe 9 where a complex mixture of ionocovalent and purely covalent bonds was found [20,26].…”

“…In some cases, these structures largely differ (in terms of quantity of defects) from those obtained by the common melt-quenching (MQ) technique used for the preparation of bulk glasses. It appears that g-GeS x (with x = 2, 4, 6) films, obtained by pulsed laser deposition from the pristine bulk glasses (obtained by MQ), show a significant content of defects and "wrong bonds" [7][8][9]. In this case, the departure from perfect chemical order is due to the fact that as-deposited g-GeS x films are far away from the equilibrium state [7].…”

Structure and optical properties of amorphous GeSx films prepared by PLD

“…Due to the significant properties such as non-toxicity, good thermal and chemical stabilities and the large optical transmission range extending in the mid-infrared, Ge-S glasses have been widely studied for many years for the potential applications in optics, optoelectronics and electrochemistry [1][2][3][4][5][6]. Great efforts were paid to the structural properties of Ge-S bulk glasses by various techniques such as Raman scattering spectra [1,3,7], neutron diffraction [2,8], EXAFS [9] and positron annihilation technique [4].…”

Molecular Modeling of Glassy Surfaces

“…In some cases, these structures largely differ (in terms of quantity of defects) from those obtained by common melt-quenching methods used for the preparation of bulk glasses. It appears that glassy GeS x (with x = 2, 4, 6) films, obtained by pulsed laser deposition from the pristine bulk glasses, show a significant content of defects and "wrong bonds" (such as homopolar bonds) [42][43][44]. In this case, the departure from perfect chemical order is due to the fact that as-deposited g-GeS x films are far away from the equilibrium state [42][43][44].…”

“…It appears that glassy GeS x (with x = 2, 4, 6) films, obtained by pulsed laser deposition from the pristine bulk glasses, show a significant content of defects and "wrong bonds" (such as homopolar bonds) [42][43][44]. In this case, the departure from perfect chemical order is due to the fact that as-deposited g-GeS x films are far away from the equilibrium state [42][43][44]. For the case of glassy GeS 2 (g-GeS 2 , g stands hereafter for glass) the perfect chemical order corresponds to the absence of any undercoordinated or overcoordinated Ge atoms or S atoms ( = 4 and = 2 for Ge and S, respectively) [45].…”