Characterization and surface modification of CuGaSe2 thin films by photoelectrochemical methods

Acidic aqueous electrolyte/semiconductor contacts have been used to measure basic material properties of thin film polycrystalline CuGaSe2 and to modify its composition (growth of a Zn containing interface layer or removal of excess Cu2Se). Although simple models are applied to a complex situation for the characterization, the comparison of different techniques (capacitance and photocurrent collection) and trends versus film composition can enlighten our view of the properties of the semiconducting films. Interfacial chemical modifications, with excellent control, can be performed with this kind of approach and represent an alternative to pure chemical bath deposition for the buffer layers involved in the CuGaSe2/Buffer/ZnO devices, as well as an alternative to the cyanide etching of the undesirable Cu2Se from the Cu-rich CuGaSe2 films, that posses otherwise high quality properties. A first feedback onto solid state devices is investigated and results can be considered as promising.