Copper indium diselenide (CuInSe2:CIS) pn-homojunction diodes were fabricated by the thermal diffusion of Zn into the p-type CIS films at 300 degrees C for 5 min using a dimethylzinc [(CH3)(2)Zn:DMZn] vapor. This method does not require any additional processing equipment since the diffusion can be carried out subsequent to the selenization of a Cu-In precursor using organoselenium liquid, such as diethylselenide [(C2H5)(2)Se:DESe]. A donor-to-acceptor pair emission attributable to Zn impurity was observed in the low-temperature photoluminescence spectrum. From the capacitance-voltage characteristics, the depletion layer width and diffusion potential of the junction were estimated as 300 nm and 0.6-0.7 V, respectively. The method is highly advantageous for the development of low-cost solar modules. (C) 2007 Elsevier B.V. All rights reserved.