Photoluminescence and states in the bandgap of germanium sulfide glasses

Temperature dependence of the photoinduced fatigue-recovery phenomena of photoluminescence under prolonged irradiation in GeS2 chalcogenide glass

“…We have additionally measured at 130, 170 and 230 K, but the time dependence was not checked. We confirmed in the previous study that the PL fatigue of Ge-S glasses under 77 K has almost fully recovered after relaxation in the dark for 30 h at RT [10]. For the present study, we have checked in advance that the full recovery and reproducible measurements can be achieved after relaxation at RT in the dark over 40 h in order to make full use of the same sample to repeat a measurement for mutual comparison.…”

“…The preparation details were described in Ref. 10. The samples were well polished to $1 mm of thickness and were mounted on the cold head of a closed-cycle He-gas refrigerator equipped with optical quartz windows and cooled down to $6 K. The temperature can be controlled within ±0.1 K using a heat control device.…”

“…In our previous study, we chose Ge-S system to understand the electronic states at around bandgap and the PL fatigue under prolonged irradiation by excitation light [10][11][12]. For the PL fatigue, furthermore, we have reported the partial recovery of the fatigued PL at 77 K [12].…”

Photoluminescence properties in Pr3+-doped chalcogenide glass

“…1, optical bandgap of the glass lies at 2.3-2.4 eV (500-550 nm), although it is not clear in the presence of the 3 P 0 and 3 P 1 states. This is about 0.2 eV smaller than those of the Ge-S glasses [14,15], which are expected to have crystalline-GeS 2 -like structure in their shortto medium-range order [16,17]. If the bandgap of the sulphide glasses in this study is characterized by Ge-S bonds in the GeS 2 -like structure, the bottom of the conduction band and the top of the valence band just above and below the bandgap are the Ge-S anti-bonding states and the S 3p lone-pair states, respectively [18,19], and the narrowing of the bandgap which may affect the PL emission intensities is brought about by the appearance of the electronic states of the wrong bonds between metal ions [14,19].…”

Time-dependent photoluminescence fatigue-recovery phenomena in germanium sulfide glasses

“…The purpose of the present study is to clarify the fundamental process of the photo-structural properties of Ge-S chalcogenide glass. Several reports can be found for PL from Ge-S glass [21][22][23][24][25][26][27][28][29][30]. Nevertheless, these properties have not been investigated compared with other chalcogenides.…”