Abstracts Book - IMRC 2018

• SA5-P017
THE ADHERENCE OF CdS THIN FILMS CHEMICALLY DEPOSITED
ON COMMON INORGANIC SUBSTRATES
Jorge Alberto García Valenzuela 1,2 , Dagoberto Cabrera German 1,3 , Marcos Alan Cota Leal 1,3 ,
Miguel Martinez Gil 1,3 , Martha Raquel Baez Gaxiola 1 , Merida Sotelo Lerma 3
1
SMARTER-Lab nucleus for research & divulgation, A.C., , Mexico. 2 Universidad de Sonora,
Departamento de Ingeniería Química y Metalurgia, Mexico. 3 Universidad de Sonora,
Departamento de Investigación en Polímeros y Materiales, Mexico.
The bad adherence to the substrate of chemical-solution-deposited
chalcogenide thin films is a misprized current technological problem. Thus, the
objective of the present research is to properly discuss the issue of adherence
by taking as example the CdS thin films. As a substrate, we used float glass
sheets to take advantage of the chemical duality of this interesting industrial
product. We observed that the use of dilute reaction solutions to deposit CdS at
70°C leads CdS thin films that adhere only to one side surface of float glass
slides, while a concentrate reaction solution leads CdS thin films that adhere to
both sides. To explain the observations, both surfaces of a Corning float glass
microscope slide were analyzed by X-ray photoelectron spectroscopy, and the
results confirmed a clear chemical difference between both surfaces: the side
that allows good adherence with the CdS film deposited a dilute reaction
solution shows intense Sn 3d peaks (tin-bath side). It was deduced that both the
surface chemical composition of the substrate and the concentration of Cd 2+ in
the reaction solution play important roles in the adherence of the CdS thin films.
As a result, a general surface reaction scheme is presented as a basis to explain
the adherence of CdS thin films to different kinds of substrates. This reaction
scheme considers both the chemical entities of the substrate surface and the
hidroxo–cadmium–thiourea species of the reaction solution, as well as the
formation of a surface intermediate entity, whose production is favored by the
increase in the amount of the two former, and which dissociates into a CdS
molecule bound to the surface and certain byproducts.
Keywords: CADMIUM SULFIDE, SEMICONDUCTORS, ADHERENCE
Presenting authors email: marcoscota@hotmail.com