CHEMICAL-VAPOR TRANSPORT BY GAS (CVTG) - OPTIMIZATION OF THE SYSTEM FOR CDS THIN-FILM DEPOSITION

A new thin film deposition technique called chemical vapour transport by gas (CVTG) was optimized for intrinsic as well as for extrinsic CdS thin film deposition. The film deposition was carried out in a quartz tube kept inside a tubular furnace. The chemical vapour transport was done using CdS powder as well as screen-printed films of CdS with CdC l2 as the flux. The nature of the film depends on parameters like the substrate temperature (distance from the source), the cooling rate and the sublimation temperature of CdS (the presence of CdCl2 in the CdS powder). The extrinsic films showed an electrical conductivity of the order of 10(1) Ohm(-1) cm(-1) and the films which showed intrinsic nat ure exhibited a conductivity of the order of 10(-8) Ohm(-1) cm(-1). Th e CVTG system was optimized for growing CdS films for solar cell and p hotodetector applications.