Showing papers on "Chemical bath deposition published in 1992"

Chemical Bath Deposition of Cadmium Sulfide Thin Films. In Situ Growth and Structural Studies by Combined Quartz Crystal Microbalance and Electrochemical Impedance Techniques

Abstract: Chemical bath deposition of CdS layers, using the ammonia process, have been studied for the first time by combined in situ quartz crystal microbalance and electrochemical impedance techniques. Both allow monitoring of the growth kinetics, but an important result is that information about the covering properties of the film, its internal structure, and the evolution of the structure during the growth, have been obtained from combined experiments. The film is shown to have in general a duplex structure with an inner compact layer (only measured by capacitance) and an outer porous layer, growing at longer reaction times. In this paper the influence of the thiourea concentration on this structure is studies and discusses. Thiourea in excess is found to be very favorable for obtaining total coverage of the substrate with a minimum thickness of the CdS film ({approx}30 nm on unactivated gold substrate), which is important for applications. A simple columnar growth model has been derived which accounts well for the experimental results.

Chemical Bath Deposition of CdS Thin Films: Electrochemical In Situ Kinetic Studies

Abstract: Chemical bath deposition of cadmium sulfide thin films from solutions has been studiedin situ using electrochemical open‐circuit potential change (EOCPC) measurements. An explanation of the EOCPC dependence with film thickness in terms of space‐charge region theory has been reported. The effect of various parameters on the growth and on the film quality is presented (temperature, concentration of reacting species, and film thickness). The structural and electrical properties of thin films prepared by this method have been studied. The x‐ray diffraction analysis shows evidence that the orientation perpendicular to the substrate surface is highly preferential confirming that the growth evolves from nucleation on the substrate. From resistivity and EOCPC measurements the following values of the electrical properties of the material have been obtained: dark conductivity about 10−7 (Ω cm)−1, photoconductivity about 10−2 (Ω cm)−1, carrier concentration about 10−13 cm−3, and carrier mobility about 2 cm2 V−1 s−1.

ELECTRODEPOSITED CdTe FOR THIN FILM SOLAR CELLS

Abstract: Large area 300 mm x 300 mm CdS/CdTe solar cells with record efficiencies over 10% have been fabricated using a reproducible, safe and low cost electrodeposition route for CdTe deposition. CdS window layers have been grown using chemical bath deposition which produces uniform adherent films by a cost effective route. Electrical characterization of small area (0.02 cm2) devices confirms that the structure is p-n rather than p-i-n. Module reliability tests show efficiency stability for more than 16,000 hours outside, and very little change using indoor environmental tests.

Preparation and characterization of pulse-plated CdSe films

Abstract: Pulse deposition at room temperature was applied to obtain CdSe thin filmsfrom an aqueous bath consisting of CdSO,and Se02 on titanium substrates, employinga range of current densities from 80—550 mA cm .2• The films were polycrystallinewith a hexagonal structure. The pulse deposited films were observed to show greateruniformity and larger grain sizes than the conventionally deposited ones. The films,heat—sensitized and vacuum annealed, showed a flat—band potential of —1.17 V (SCE)and a high energy conversion efficiency of 6.3% at 60 mW cm 2in polysulphide redoxafter photoetching. The optical band gap was 1.7 eV.1. INTRODUCTIONCdSe, with a direct band gap of 1.7 eV, is a promising candidate for solarenergy conversion. MIS type solid state solar cells and PEC cells based on CdSeare being actively investigated. Several methods like vacuum evaporation, spraypyrolysis, chemical bath deposition, screen printing, electrodeposition etc., havebeen employed for the preparation of CdSe films. We report here results on pulse

Chemical Bath Deposition of Cadmium Sulfide Thin Films. In situ Growth and Structural Studies by Combined Quartz Crystal Microbalance and Electrochemical Impedance Techniques.

Abstract: Chemical bath deposition of CdS layers, using the ammonia process, have been studied for the first time by combined in situ quartz crystal microbalance and electrochemical impedance techniques. Both allow monitoring of the growth kinetics, but an important result is that information about the covering properties of the film, its internal structure, and the evolution of the structure during the growth, have been obtained from combined experiments. The film is shown to have in general a duplex structure with an inner compact layer (only measured by capacitance) and an outer porous layer, growing at longer reaction times. In this paper the influence of the thiourea concentration on this structure is studies and discusses. Thiourea in excess is found to be very favorable for obtaining total coverage of the substrate with a minimum thickness of the CdS film ({approx}30 nm on unactivated gold substrate), which is important for applications. A simple columnar growth model has been derived which accounts well for the experimental results.