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HL: Fachverband Halbleiterphysik

HL 48: Poster 2

HL 48.23: Poster

Donnerstag, 26. März 2009, 15:00–17:30, P2

Influence of uniaxial pressure on the optical properties of Tl₂S single crystals — •H. Danylyuk, Y. Stakhira, and V. Belyukh — Ivan Franko Lviv National University, Department of Electronics Dragomanov Str. 50, UA-79005 Lviv, Ukraine

Tl₂S single crystals were grown by the Bridgman-Stockbarger method. Samples with 50−130 µ m of thickness were freshly cleaved along the (00.1) cleavage plane from the ingot. In all investigated samples the absorption edge shape is good described by Urbach’s rule. The energy gap of Tl₂S crystal was determined by sharp change of slope of the absorption spectrum curve: E_g ≈ 1 eV. To study the low-dimensional effects in layered Tl₂S crystals we have investigated influence of uniaxial pressure on Tl₂S optical properties in absorption edge range. Pressure (0,3-1 MPa) was applied in c-axis direction. We have observed considerable increase of the absorption coefficient in transparency range near fundamental absorption edge after 1-2 days of pressure effect. For long-continued (10-12 days) pressure effect on samples, the absorption coefficient increased in a few times. However, the optical properties of Tl₂S single crystals are partly restored after stopping of pressure effect. This restoring was the better, the shortly the pressure effected the samples. For long-continued pressure effect on samples the absorption edge shape is also changed, but still it is described by Urbach’s rule. However, the characteristic Urbach’s parameters are changed.