Micropatterned CdS thin films by selective solution deposition using microcontact printing techniques

The micropatterning of CdS thin-film on Si(100) substrate with a boundary r esolution better than 100 nm was successfully obtained by a chemical bath d eposition technique and microcontact printing (mu CP) method using octadecy ltrichlorosilane (OTS) as the organic thin layer template. The selective de position and lift-off condition of patterned CdS thin films could be contro lled by the various parameters, e.g., solution concentration, pH, temperatu re, and sonicating time after the deposition. When the solution concentrati on is moderately high ([Cd] > 0.0025 M), depositions under conditions of pH 10.5-10.7, reaction temperature 60 degrees C, and Cd/thiourea/ethylenediam ine ratio 1/1/3 produced CdS films all over the OTS and unmodified Si surfa ces. The CdS on OTS layer could be lifted off by sonication in isopropyl al cohol to produce patterned CdS films. By using solutions with low concentra tion, deposition of the CdS thin films occurred selectively on the unmodifi ed Si surface and patterning could be achieved even without the lift-off pr ocess.