Fabrication of CdS thin films assisted by Langmuir deposition, self-assembly, and dip-pen nanolithography

Thin CdS films were fabricated by Langmuir deposition, self-assembly, and dip-pen nanolithography methods. Firstly, LB films of saturated arachidic acid and LS films of unsaturated 10,12-pentacosadiynoic acid were reacted with cadmium ions and exposed to H 2 S gas. Formation of CdS crystal was observed with Fourier transform infrared (FTIR) spectra and atomic force microscope (AFM). Secondly, mercaptohexadecanoic acid was self-assembled on Au substrate and was reacted with CdS colloidal particles. At pH=9.1, the density of CdS colloids immobilized on Au substrate was very high compared to one at pH=5.0. Finally, thin films of CdS were also prepared on silicon and Au substrates by cadmium chloride-coated AFM tip and successive exposure of H2S gas. Localized formation of CdS crystal was suggested with AFM and depth-profiling Auger electron microscopy (AES).