Research study of volt-amperage properties (VAP) of [Formula: see text] crystals determined the mechanism of current flow though the studied samples and this mechanism is based on barrier Schottky emission and emission of Franklin–Paul. The dielectric constant of the material, height of the potential barrier on metal–semiconductor border, concentration of the traps and the effective mass of electrons are calculated.
The investigation of photoluminescence (PL) properties of Ca(Al[Formula: see text]Ga[Formula: see text]S4:Eu[Formula: see text] solid solutions with [Formula: see text] = 0, 0.1, 0.2 and 0.3 synthesized for the first time was performed in wide temperature and excitation power density ranges. It is shown that PL intensity decreases by only 20–30% for different [Formula: see text] in the temperature range from 10 K to 300 K. The extreme stability of shape and position of the emission spectra was found in the range of excitation power density from [Formula: see text] W/cm2 to [Formula: see text] W/cm2 by nanosecond pulsed radiation. The reversible PL efficiency droop was only above 104 W/cm2 of excitation power density. The PL decay time constant was found to be of about 560 ns to 595 ns for [Formula: see text] ranging between 0.1 and 0.3 at room temperature.
Photoluminescence (PL) excitation and emission spectra of Ca(Al x Ga 1 -x ) 2 S 4 :Eu 2+ (х = 0.1, 0.2) crystals have been investigated at different temperatures (20-300 K) and europium concentrations (3, 5, 7%).The emission spectrum is a band peaking at 556 nm, which is due to 4f 6 5d → 4f 7 ( 8 S 7/2 ) transitions in the Eu 2+ion. An increase in the Eu 2+ concentration leads to an increase in the PL intensity by a factor of almost 3. Stokes shift ΔS = 0.32 eV, Huang-Rhys factor s = 10 ± 2, activation energy Е а = 0.02 and 0.03 eV, and lifetime τ = 250 ns are determined by analyzing the spectra.
Проведены исследования термолюминесценции (ТЛ) твердых растворов Ca(Alx Ga 1−x ) 2 S 4 : Eu 2+ (x = 0.1−0.3) после ультрафиолетового облучения ме-тодом линейного нагрева. Показано, что наблюдаемые максимумы ТЛ сложные и состоят из нескольких сильно перекрывающихся парциальных максимумов, определены энергия активации, сечение захвата, частотный фактор и концен-трация ловушечных уровней, ответственных за эти максимумы. С увеличением x интенсивность излучения и число пиков растет.
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