Growth and characterization of CdZnS thin film buffer layers by chemical bath deposition
In this paper we report the study of CdZnS thin films grown on the soda-lime glass (SLG) substrates by chemical bath deposition (CBD) process for buffer layer applications in CuGaSe/sub 2/ (CGS) solar cells. Structural, surface morphology, optical, and electrical properties of as-deposited CdZnS films were investigated by XRD, SEM, spectrophotometer, and four probes resistivity measurements as a function of Zn-composition in the solution. The CdZnS films have hexagonal structures. The grain size of CdZnS films was found to increase with increasing Zn-content in the solution. The films with 30% of Zn in the solution showed a better than 80% transmittance for wavelengths longer than 600 nm and film thickness less than 50 nm. The values of energy band gaps obtained are 2.40, 2.55, and 2.70 eV for Zn-content of 0, 30, and 50%, respectively. The resistivity of CdZnS films was found to increase as the Zn content increases.
Studies of ZnxCd1-xS films and ZnxCd1-xS/CuGaSe2 heterojunction solar cells
Thin film ZnxCd1-xS/CuGaSe2 heterojunction solar cells were prepared by laser evaporating CuGaSe2 onto sprayed ZnxCd1-xS films. The physical properties of ZnxCd1-xS films are discussed to study the influence of zinc content in the ZnxCd1-xS layer on the performance of the heterojunction. The photovoltaic properties of the cells were studied using illuminated current-voltage characteristics and spectral response measurements. The typical cell parameters obtained for a Zn0.5Cd0.5S/CuGaSe2 junction were Voc=710 mV, Jsc=11.8 mA cm-2, FF=0.50 with an efficiency of 4.9% on an active area of 1 cm2 without any antireflection coating.
Laser‐generated pulsed atomic beams
The irradiation of thin films of solid material by a moderate energy (0.5 J/pulse) Q‐switched ruby laser beam has been used to produce intense pulses of neutral atoms and molecules in the 1 to 10 eV energy range. For a given total laser beam energy, both the flux and energy range of atoms within the pulse can be varied within limits by adjusting the energy density of the laser light at the target surface. As observed at a distance of 60 cm from a thin BiF3 compound target, the flux of 5 eV fluorine atoms from a typical burst was estimated to be about 1.3×107 atoms/cm2/sec. For the same burst, the flux integrated over the 1 to 10 eV range yields a value of ∼2×1013 atom/cm2. Similar results were obtained with aluminum and uranium thin films.