Thin‐film Copper Indium Diselenide has been deposited using a two‐step process with solid selenium as the Se source rather than H2Se. Film properties are strongly influenced by the substrate. Borosilicate glass produces more nucleation sites and smoother thin‐films, while 1000 A˚ films deposited on soda lime glass may exhibit disconnectedness. Electronic properties are similarly affected, particularly mobilities. Using MOSFET devices as analytical tools electron channel mobilities of up to 45 cm2/Vs have been measured. Preliminary results from thin‐film transistor dynamics indicate that traps with a trapping time of about 10 seconds are controlling surface properties and limiting solar cell performance.