Preparation and electrical properties of CuInSe2 thin films by pulsed laser deposition using excess Se targets

An effective way to prepare a robust CuInSe2 (CIS) target for subsequent vapor depositions of thin films is suggested in this work. The technique involves addition of excess Se to presynthesized CIS powder followed by cold pressing and sintering at a temperature as low as 300 °C. Phase-pure chalcopyrite CIS films were prepared at a substrate temperature of 300 °C from targets that contained different amounts of excess Se. The average size of particulates, typical of the pulsed laser deposition process, and their surface coverage decreased with increasing Se content up to 50 wt% in the targets. Films grown from the target with 50 wt% excess Se exhibited a hole concentration of ˜3 × 1019 cm−3 and a Hall mobility of ˜2 cm2/Vs. With the decrease of substrate temperature to room temperature, the resistivity increased from 1.1 × 10−1 to ˜7.5 × 108 Ω·cm, which is attributed to the potential contributions of Se interstitials, CuIn, and VIn defects.