2. Articole

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

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Author: search.filters.author.Caraman, MihailSubject: search.filters.subject.Photoconductivity

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    ABSORPTION SPECTRA AND EXTRINSIC PHOTOCONDUCTIVITY OF Cu AND Cd DOPED GaSe SINGLE – CRYSTAL FILMS
    (2006) Cuculescu, Elmira; Evtodiev, Igor; Caraman, Mihail; Rusu, George G.
    GaSe single crystal films were doped during growth process with Cu or Cd atoms with concentration ranged between 0.05 and 0.50 at. %. Single crystal films (with thickness about 0.5 μm) were obtained by mechanical splitting of bulk single crystals. Impurity concentration was determined using atomic emission spectroscopy. Spectral dependences of absorption coefficient and photoconductivity were studied in the range 1.50 eV – 3.70 eV. It was experimentally established that the absorption spectra have an additional absorption band and its corresponding energy depends on the nature (Cu or Cd) and concentration of the doping atoms. Also, independently on the presence of the dopant, other two absorption bands in the IR region are present.
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    ELECTRONIC TRANSPORT AND PHOTOCONDUCTIVITY OF POLYCRYSTALLINE CdSe THIN FILMS
    (2006) Baban, Cristian Ioan; Caraman, Mihail; Rusu, Gheorghe Ioan
    In this paper we have studied the electrical properties and photoconductivity of CdSe thin films, prepared by vacuum evaporation using the quasi-closed volume technique. It was found that the films were polycrystalline with a hexagonal (würtzite) structure and the crystallites are highly oriented with the (002) planes paralel to substrate. The film surface was investigated by means of SEM. The temperature dependence of electrical conductivity and Seebeck coefficient was studied. The films have n-type conduction. The spectral characteristics of photoconductivity were studied at 78 K and 300 K in the wavelength range 300–1100 nm. The bandgap energy (1.53–1.63 eV) calculated by using the Moss rule is smaller than those determined from absorption spectra. For the diffusion length, determined form absorption spectra and spectral dependence of photoconductivity, values between 0.22 and 0.29 μm were found.
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    ON THE PHOTOCONDUCTIVITY OF Bi2 O3 IN THIN FILMS
    (2000) Leontie, Liviu; Caraman, Mihail; Rusu, Gheorghe Ioan
    The spectral characteristics of photoconductivity for Bi2 O3 thin films were investigated. The films were prepared by thermal oxidation in air of Bi evaporated films. As revealed by X-ray diffraction and polarizing microscopy studies, polycrystalline and multiphasic films were obtained. From the photoconductivity spectral curves, the bandgap energy values were determined, by using the Moss criterion. The influence of oxidation (preparation) conditions on the Eg values is discussed. The photoconductivity of Al-Bi 2 O3 -Al, Cu-Bi 2 O3 -Cu and Al- Bi 2 O3-In 2 O3 structures is also investigated.