First observation of the temperature-dependent light-induced response of Ge(25)As(10)Se(65) thin films

Observation of photobleaching in Ge-deficient Ge16.8Se83.2 chalcogenide thin film with prolonged irradiation

We presented the unusual result of photobleaching (PB) in Ge-deficient Ge_16.8Se_83.2 thin films with continuous irradiation with 560 nm laser for 12000 s, which is contradicted with the previous reports that the PB only occurs in Ge_xSe_100-x films with x > 30. Observation of the dynamics variations of the photo-induced effects indicated that, photodarkening (PD) appears almost instantaneously upon light irradiation, saturates faster in a shorter time scale, and then photobleaching (PB) becomes dominant. Moreover, both PD and PB process accelerates with increasing irradiation power density. Raman spectra provided the evidence on the change of the photostructure of the samples, e.g. the structural transformation from Ge(Se_1/2)₄ edge-sharing (ES) to corner-sharing (CS) tetrahedral and homopolar Ge-Ge and Se-Se bonds to heteropolar Ge-Se bonds.

Tuning nanosecond transient absorption in a-Ge₂₅As₁₀Se₆₅ thin films via background illumination

In this Letter, we report for the first time, to the best of our knowledge, continuous-wave laser background illumination (BGI) as a simple and yet useful tool to tune nanosecond transient absorption (TA) in a-Ge25As10Se65 thin films. In our experiments, we observed remarkable blueshift in TA as a function of the BGI intensity. Strikingly, relaxations of TA in background-illuminated samples are much faster than the as-prepared samples. This observation provides new insights into the bond-breaking mechanism. Further, decay time constants of TA are wavelength dependent, which signifies that excited carriers have a longer lifetime in deep traps than in shallow traps.