However, few have been reported on the precursor films generated by sputtering a CIG target.

A、
A、 Explaining the significance or necessity of the research;
B、
B、 Reviewing the existing literature relevant to the present study;
C、
C、 Identifying a gap in the existing literature;
D、
D、 Announcing the purpose/focus of the study;
E、
E、 Outlining the paper structure