Dimitrina Petrova Kerina

Mrs. Dimitrina Petrova Kerina


Research Focus & Metrics

Academic Career Length

4Years (2023-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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22 February 2023 in Nanomaterials
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Journal Article
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DKDimitrina Petrova Kerina
Dimitrina Petrova Kerina
BNBlagovest Napoleonov
Blagovest Napoleonov
CMChau Nguyen Hong Minh
Chau Nguyen Hong Minh
Vera MarinovaVera Marinova
Vera Marinova
YLYUPIN LAN
YUPIN LAN
DDDimitre Dimitrov
Dimitre Dimitrov
In this paper, aluminum-doped zinc oxide (ZnO:Al or AZO) thin films are grown using atomic layer deposition (ALD) and the influence of postdeposition UV–ozone and thermal annealing treatments on the films’ properties are investigated. X-ray diffraction (XRD) revealed a polycrystalline wurtzite structure with a preferable (100) orientation. The crystal size increase after the thermal annealing is observed while UV–ozone exposure led to no significant change in crystallinity. The results of the X-ray photoelectron spectroscopy (XPS) analyses show that a higher amount of oxygen vacancies exists in the ZnO:Al after UV–ozone treatment, and that the ZnO:Al, after annealing, has a lower amount of oxygen vacancies. Important and practical applications of ZnO:Al (such as transparent conductive oxide layer) were found, and its electrical and optical properties demonstrate high tunability after postdeposition treatment, particularly after UV–Ozone exposure, offers a noninvasive and easy way to lower the sheet resistance values. At the same time, UV–Ozone treatment did not cause any significant changes to the polycrystalline structure, surface morphology, or optical properties of the AZO films.

17 July 2024 in Nanomaterials
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Journal Article
Open access
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BNBlagovest Napoleonov
Blagovest Napoleonov
DKDimitrina Petrova Kerina
Dimitrina Petrova Kerina
NMNikolay Minev
Nikolay Minev
PRPeter Metodiev Rafailov
Peter Metodiev Rafailov
Vladimira Stoyanova VidevaVladimira Stoyanova Videva
Vladimira Stoyanova Videva
Vera MarinovaVera Marinova
Vera Marinova
We report a two-step growth process of MoS2 nanoflakes using a low-pressure chemical vapor deposition technique. In the first step, a MoS2 layer was synthesized on a c-plane sapphire substrate. This layer was subsequently re-evaporated at a higher temperature to form mono- or few-layer MoS2 flakes. As a result, the close proximity re-evaporation enabled the growth of pristine MoS2 nanoflakes. Atomic force microscopy analysis confirmed the synthesis of nanoclusters/nanoflakes with lateral dimensions of over 10 μm and a flake height of approximately 1.3 nm, demonstrating bi-layer MoS2, whereas transmission electron microscopy analysis revealed triangular MoS2 nanoflakes, with a diffraction pattern proving the presence of single crystalline hexagonal MoS2. Raman data revealed the typical modes of high-quality MoS2 nanoflakes. Finally, we presented the photocurrent dependence of a MoS2-based photoresist under illumination with light-emitting diode of 405 nm wavelength. The measured current–voltage dependence across various luminous flux outlined the sensitivity of MoS2 to polarized light and thus opens further opportunities for applications in high-performance photodetectors with polarization sensitivity.