Papers by Author: Laurentiu Fara

Abstract: Cuprous oxide (Cu₂O) has a high optical absorption coefficient and favourable electrical properties, which make Cu₂O thin films attractive for photovoltaic applications. Using reactive radio-frequency magnetron sputtering, high quality Cu₂O thin films with good carrier transport properties were prepared. This paper presents the characteristics of Cu₂O thin films that were sputter deposited on quartz substrates and subjected to post-deposition rapid thermal annealing. The thickness of the thin films and the optical constants were determined by ellipsometry spectroscopy (SE). The optical transmittance increased in lower wavelength region after annealing at 900 ̊C in rapid thermal annealing (RTA). The structural and morphological properties of the Cu₂O thin films were investigated by electronic scanning microscopy (SEM) and atomic force microscopy (AFM), whereas elemental analysis was performed by X-ray fluorescence spectroscopy (XRF). The carrier mobility, carrier density and film resistivity were changed after post-deposition rapid thermal annealing from respectively ~14 cm2/Vs, ~2.3 x 10¹⁵ cm^-3 and ~193 Ωcm for the as-deposited Cu₂O film to ~49 cm2/Vs, ~5.0 x 10¹⁴ cm^-3 and ~218 Ωcm for the annealed Cu₂O film. The investigation suggests that the sputter-deposited Cu₂O thin films have good potential for application as absorber layers in solar cells.

Abstract: The paper discussed the solar cells based on Cu-CdS contact assimilated to a heterojunction. Two methods were considered for our analysis: the rate equations approach and the stochastic equation one. The both permitted to obtain interesting information concerning the specific contact and are characterized by the order parameter.