2. Articole

Permanent URI for this collectionhttps://msuir.usm.md/handle/123456789/47

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Subject: search.filters.subject.zinc selenide

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    SECONDARY ION MASS SPECTROSCOPY OF ZINC SELENIDE CRYSTALS WITH PHOTOCONDUCTIVITY SPECTRAL MEMORY
    (2017) Belenciuc, Alexandr; Ilinykh, Nicolai; Kovalev, Leonid
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    RECENT ADVANCES IN ZnSe-BASED DEVICES: FROM UV TO TERAHERTZ APPLICATIONS
    (CEP USM, 2024) Sirkeli, Vadim P.; Nedeoglo, Natalia D; Nedeoglo, Dmitrii D.; Vatavu, Sergiu A.; Yilmazoglu, Oktay; Hajo, Ahid S.; Preu, Sascha; Hartnagel, Hans L.; Küppers, Franko
    Zinc selenide is a II-VI compound material with wide bandgap. Due to its unique properties like direct wide bandgap, high resistance to intense UV and X-Ray radiation, ZnSe is attractive material for fabrication of many photonic and electronic devices. In this paper we report on recent advances on ZnSe-based optoelectronic devices covering spectral region from ultraviolet to terahertz.
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    RECENT ADVANCES IN TERAHERTZ TECHNOLOGY FOR SECURITY AND BIOMEDICAL APPLICATIONS
    (Universitatea de Stat din Tiraspol, 2021) Sirkeli, Vadim
    Terahertz waves have low photon energies (~ 4.1 meV for 1 THz), which is about 1 million times weaker than the energy of X-ray photons. They do not cause any harmful ionization in biological tissues. The terahertz radiation is strongly attenuated by water and is very sensitive to water content. This paper provides current status and recent advances in terahertz technology for security and medical applications. In particular, we report on our designs of THz quantum cascade lasers to identify cancerous tissues and other medical issues.
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    EFFECT OF p-NiO AND n-ZnSe INTERLAYERS ON THE EFFICIENCY OF p-GaN/n-ZnO LIGHT-EMITTING DIODE STRUCTURES
    (IOP Publishing Ltd, 2015) Sirkeli, Vadim; Yilmazoglu, Oktay; Küppers, Franko; Hartnagel, Hans
    We report on a numerical study of the characteristics of p-GaN/n-ZnO light-emitting diodes (LEDs) with p-NiO and n-ZnSe interlayers, and on LED design optimization which includes bandgap engineering, thickness and doping of constituent layers. The current-voltage dependences of investigated LEDs show a threshold voltage of 3.1 V, 5.4 V and 5.6 V for LED devices without and with the presence of p-NiO and n-ZnSe interlayers, respectively. It is found that p-NiO, n-ZnSe and n-ZnO interlayers act as an electron blocking layer, active media layer, and electron transport layer, respectively. It is established that the insertion of both p-NiO and n-ZnSe interlayers leads to the enhancement of charge carrier-confinement in the active region and to the significant increase of internal quantum efficiency (IQE) of the LED device up to 82%, which is comparable with IQE values in order to obtain better AlGaN- and InGaN-based LEDs. It is found that the efficiency of LED devices at 100 A cm−2 is equal to 0.024, 0.09 and 16.4% of external quantum efficiency (EQE), 1.3 × 10−4, 1.6 × 10−4, and 6.4 lm W−1 of PE, and 1.3 × 10−4, 2.9 × 10−4, and 12 cd A−1 of CE for p-GaN/n-ZnO, p-GaN/p-NiO/n-ZnO, and p-GaN/p-NiO/n-ZnSe/n-ZnO LED devices, respectively.
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    ZnSe-BASED SOLAR-BLIND ULTRAVIOLET PHOTODETECTORS WITH DIFFERENT SCHOTTKY CONTACT METALS
    (CEP USM, 2021) Sirkeli, Vadim; Nedeoglo, Natalia; Nedeoglo, Dmitrii; Yilmazoglu, Oktay; Hajo, Ahid; Preu, Sascha; Kuppers, Franko; Hartnagel, Hans
    We report on the selection of contact metallisations for ZnSe-based metal-semiconductor-metal ultraviolet photode- tectors. Our evaluation is based on Ni/Au, Cr/Au, and hybrid Ag-nanowire contacts. Low values of dark current of 0.32 nA, 0.82 nA and 1.64 nA at bias voltage of 15 V were achieved for photodetectors with Ag-NW, Ni/Au and Cr/Au interdigital contacts, respectively. The best performance of our ZnSe-based ultraviolet photodetectors is observed for Ni/Au interdigital contacts. This is due to the higher Schottky barrier height, which is equal to ~ 1.49 eV for Ni/Au contacts in comparison with ~ 1.26 eV for Cr/Au contacts. A very high responsivity of 5.40 AW-1 at bias voltage of 15 V for light with a wave- length of 325 nm is obtained for devices with Ni/Au interdigital contacts. Moreover, the maximum of photocurrent on/off ratio of 20342 and minimum of NEP of ~ 3 × 10-15 W Hz-1/2 at bias voltage of 15 V was achieved for this type of device.