There are several reasons. First, I would like to broaden my career choice. In my major, there is very limited options even after graduated from master course. And I also found some pleasure during my master research, and I personally think I did a good job. And the most important reason is that this program is really attractive to me. If I am lucky enough to have this position, I will deepen and widen this research, participate conferences and publish article as much as possible.