Thin-film CuGaSe2 - Physical properties and photovoltaic potential

CuGaSe2 thin films were fabricated by coevaporation of the elements. Their optical, electrical, and structural properties have been studied. P-type, single (tetragonal) phase films were obtained at a substrate temperature of 450 C. The composition of the films was varied, and resistivities from 0.1 to 1,000,000 ohm cm and optical band gaps between 1.66 and 1.69 eV were measured. A CdS/CuGaSe2 device was fabricated with a 2.8-micron CuGaSe2 thin film with a slight Cu deficiency and a resistivity of aobut 3000 ohm cm. The electron-beam-induced current maximum for this device lies at the CuGaSe2/CdS interface, indicating heterojunction behavior.