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18 results on '"Zoita, Nicolae Catalin"'

10. Heteroepitaxial β‐Ga2O3 on Conductive Ceramic Templates: Toward Ultrahigh Gain Deep‐Ultraviolet Photodetection.

Author

Alfaraj, Nasir, Li, Kuang‐Hui, Alawein, Meshal, Kang, Chun Hong, Braic, Laurentiu, Zoita, Nicolae Catalin, Kiss, Adrian Emil, Ng, Tien Khee, and Ooi, Boon S.

Subjects
ACTION spectrum, DECAY constants, TITANIUM nitride, CERAMICS, SINGLE crystals, NITRIDES, TIN
Abstract

This article investigates the ultrahigh sensitivity and DUV photodetection capability of a hybrid oxide‐nitride stack comprising β‐Ga2O3 layers grown heterogeneously on a conductive ceramic crystal. The ceramic crystal, namely a TiN interlayer, which acts as a lattice template, was heteroepitaxially grown on bulk MgO. Because β‐Ga2O3 is a monoclinic phase crystal, it is conjectured that its nucleation and growth process on cubic phase TiN is entropic in nature, whereby the two unit cell configurations of the β‐Ga2O3 crystal, exhibiting rotational twin domains, grew alternately side by side in a semiperiodic manner on TiN while maintaining a single crystal phase. This film formation mechanism contributed to the introduction of additional defects in the β‐Ga2O3 lattice (Taylor's dislocations in addition to growth‐induced vacancies). The fabricated DUV photodetectors based on the resulting metal‐semiconductor junction heterodiodes exhibited an average peak spectral responsivity of 276.72 A W−1 and fast decay constants in the order of 500 ms in the ultraviolet‐C regime, with true solar‐blind characteristics manifested by ultraviolet‐to‐visible rejection ratios of up to 2 × 103 and illuminating power density of around 70 μW cm−2. The crystallographic orientation relationships between the TiN and β‐Ga2O3 crystals, as well as the lattice fit and dislocation types, are revealed and examined. [ABSTRACT FROM AUTHOR]

Published
2021
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15. Tunable Optical Properties of SiN x Thin Films by OES Monitoring in a Reactive RF Magnetron Plasma.

Author

Pana, Iulian, Vitelaru, Catalin, Zoita, Nicolae Catalin, and Braic, Mariana

Subjects
SPUTTERING (Physics), SILICON nitride, ARGON, NITROGEN, PLASMA layers, HYSTERESIS
Abstract

The reactive sputter deposition of SiN x with tunable optical properties is approached by OES combined with subsequent thin films characterization. The reactive process involves the sputtering of a silicon target under RF bias in an argon/nitrogen gas mixture. The nitrogen mass flow ratio FR = N2/(N2 + Ar) is used as main control parameter, and the evolution of selected emission lines is followed in order to describe the main process intervals. It is shown that the sputtering process has no hysteresis behavior in a broad interval of FR (0-90%). The main process window is established for FR in the range 5-30%, and within this window, the evolution of plasma emission lines and film's optical properties are discussed and correlated. [ABSTRACT FROM AUTHOR]

Published
2016
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16. Preparation of Bulk Polycrystalline MnGexSby (x = 0.5-1.0; y = 1.5-2.2) Doped with Co or Fe

Author

Rusu, Madalin Ion, Tenciu, Daniel, Zoita, Nicolae Catalin, Notonier, Roger, Tonetto, Alain, and Grigorescu, Cristiana Eugenia Ana

Abstract

Bulk polycrystalline MnGexSby materials doped with Co or Fe were prepared and investigated with the aim of obtaining new diluted magnetic semiconductor (DMS) materials. An innovative preparation method was also established. Investigation techniques like X-ray diffraction (XRD), Raman scattering, and scanning electron microscopy (SEM) associated with energy dispersive X-ray analysis (EDX) have been employed to derive the structural properties and the composition of the bulk material.

Published
2015
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