N. S. Yuksek

Thermally stimulated current analysis of shallow levels in TlGaS2 layered single crystals

We have carried out thermally stimulated current measurements on as-grown TlGaS2 layered single crystals in the temperature range of 10–60 K with various heating rates. We found experimental evidence for the presence of three trapping centres in TlGaS2, located at 6, 12 and 26 meV. We have determined the trap parameters using various methods of analysis, and these agree well with each other. The retrapping process is negligible for these levels, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.

Temperature-?and excitation intensity-dependent photoluminescence in TlInSeS single crystals

Photoluminescence (PL) spectra of TlInSeS layered single crystals were investigated in the wavelength region 460–800 nm and in the temperature range 10–65 K. We observed one wide PL band centred at 584 nm (2.122 eV) at T = 10 K and an excitation intensity of 7.5 W cm−2. We have also studied the variation of the PL intensity versus excitation laser intensity in the range from 0.023 to 7.5 W cm−2. The red shift of this band with increasing temperature and blue shift with increasing laser excitation intensity was observed. The PL was found to be due to radiative transitions from the moderately deep donor level located at 0.243 eV below the bottom of the conduction band to the shallow acceptor level at 0.023 eV located above the top of the valence band. The proposed energy-level diagram permits us to interpret the recombination processes in TlInSeS layered single crystals.

Thermally stimulated currents in n-InS single crystals

Thermally stimulated current measurements are carried out on as-grown n-InS single crystals in the temperature range of 10–125 K. Experimental evidence is found for four trapping centers present in InS. They are located at 20, 35, 60 and 130 meV. The trap parameters have been determined by various methods of analysis, and they agree well with each other. # 2002 Elsevier Science Ltd. All rights reserved.