CuGaSe2 thin films prepared by a novel CCSVT technique for photovoltaic application

A novel chemical close-spaced vapor transport (CCSVT) technique has been developed for the growth of the CuGaSe2 (CGSe) thin films on areas as large as 10 X 10 cm(2). Cu precursors deposited on clean and Mo-coated soda lime glass substrates are thermally and chemically treated under gaseous GaClx/H2Se atmosphere in the CCSVT cell. The Ga2Se3 employed as source material is stoichiometrically volatilised at 550 degreesC by a controlled amount of HCI/H-2 agent. Single phase CGSe thin films are prepared with a growth rate of 230-240 nm/min by using a single stage process. A two-stage process is applied for the fine tuning of the CGSe composition and electronic properties appropriate for the subsequent solar cell preparation. Film characterisation including X-ray diffraction measurements, scanning electron microscopy observations, X-ray fluorescence analysis and elastic recoil detection analysis has been carried out. An 8.7% active area efficient ZnO/CdS/CuCaSe2 solar cell under AM1.5 conditions has been achieved. (C) 2003 Elsevier B.V. All rights reserved.