Single-step growth of high quality CIGS/CdS heterojunctions using Pulsed Laser Deposition

This work reports on the utilization of pulsed laser deposition (PLD) for the preparation of CdS thin films and CdS/Cu(In,Ga)Se-2 heterojunction structures on soda-lime glass (SLG) and Mo-coated SLG substrates, respectively, under various process conditions. Single phase, stoichiometric and high optical quality CdS films are obtained at a fluence of 1.1 J/cm(2) and at deposition temperatures of 200-400 degrees C. The results of this investigation were used to grow CdS on Cu(In,Ga)Se-2/Mo/SLG. Both Cu(In,Ga)Se-2 and CdS layers have been deposited sequentially using PLD without interrupting the deposition process. The influence of CdS deposition temperature on the properties of CdS/Cu(In,Ga)Se-2 heterojunction has been extensively studied and is reported herein for the first time. Low series and high shunt resistances are obtained for the samples where CdS was grown at 200 and 300 degrees C. The CdS/Cu(In,Ga)Se-2 diode grown at CdS deposition temperature of 300 degrees C exhibits the lowest ideality factor and leakage current, indicating the better quality of the diode. The results of this work demonstrate that high-quality CdS/Cu(In,Ga)Se-2 diodes are obtained using pulsed laser deposition in a single-step growth process, eliminating the need for selenization of Cu(In,Ga)Se-2 and the use of other growth techniques such as chemical bath deposition for CdS.