LOW PRESSURE MOCVD OF COPPER BASED COMPOUNDS FOR PHOTOVOLTAIC APPLICATIONS

Abstract
In recent years copper based compounds such as copper indium diselenide (CuInSe₂, CIS) have emerged as the most promising candidates for high efficiency stable solar cells. To date research has been centred around the standard thin film deposition techniques i.e. evaporation, sputtering and electroplating. While these techniques give good films it has proved difficult to gain reproducible results. The production of devices based on CIS thin films has now progressed to a point where, to achieve further advances in device efficiency, more research into alternative deposition techniques and the basic deposition parameters is required. The major problems encountered with the standard technique are poor step coverage and lack of control over the stoichiometry. A low pressure MOCVD reactor has been constructed to investigate the growth of thin film CIS and the factors affecting deposition. The considerations involved in the design of such a system are discussed. A detailed study of reactor parameters affecting low pressure MOCVD of copper, copper indium and copper indium diselenide is being carried out. Mass spectrometric analysis of the decomposition products has been undertaken and the growth mechanisms and kinetics involved in these deposition processes are king investigated.