TY  - EJOU
AU  - Toreniyaz, Zhadyra 
AU  - Ismailova, Guzal 
AU  - Prikhodko, Oleg 
AU  - Nakysbekov, Zhasulan 
AU  - Kuanyshbekov, Tilek 
AU  - Tolep, Nurkadam 
AU  - Terekhov, Dmitry 
AU  - Tolepov, Zhandos 

TI  - Photoelectric Properties of Amorphous Selenium Thin Films Deposited by Thermal Evaporation
T2  - Chalcogenide Letters

PY  - 2026
VL  - 23
IS  - 5
SN  - 1584-8663

AB  - Amorphous selenium (a-Se) thin films were deposited by vacuum thermal evaporation and investigated in planar photoconductive structures to evaluate their optical and photoelectrical properties in the low-field regime. SEM analysis showed continuous film coverage with a thickness of about 250 nm. Raman spectroscopy and X-ray diffraction confirmed the amorphous structure of the as-deposited films and the formation of trigonal crystalline selenium after annealing. Optical analysis based on transmission and reflectance spectra yielded an optical band gap <mml:math id="mml-ieqn-1">
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</mml:math> and an Urbach energy <mml:math id="mml-ieqn-2">
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</mml:math>, indicating localized tail states associated with structural disorder. The planar devices exhibited nearly linear and symmetric dark current-voltage characteristics within <mml:math id="mml-ieqn-3">
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</mml:math>, corresponding to an electric field range of 100–1000 V/cm. Under illumination at <mml:math id="mml-ieqn-4">
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</mml:math>, the photocurrent showed a sublinear dependence on incident light power density, <mml:math id="mml-ieqn-5">
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</mml:math>. The responsivity increased with the electric field, which indicates more efficient collection of photogenerated carriers at higher bias. Temperature-dependent measurements over the range 303–343 K showed that both the dark current and the current under illumination increase with temperature, whereas the relative photoresponse decreases because the dark current increases more rapidly. Arrhenius analysis yielded effective activation energies 0.836 eV for the dark current and 0.709 eV for the current under illumination. These results show that the optical disorder parameters and the photoelectrical response are mutually consistent. In weak electric fields, the behavior of planar a-Se films is governed by competition between thermally activated dark conduction and field-assisted collection of photogenerated carriers.
KW  - Amorphous selenium; thermal evaporation; low-field photoconductivity; planar photodetector; Urbach energy

DO  - 10.32604/cl.2026.081101