A semiconductor device including first to fourth points defined using In ion intensity, Si concentration, and C concentration obtained from SIMS data. The active layer of the device is a first region between the first point and the second point. In addition, the C concentration in a third region between the third point and the fourth point is higher than the C concentration in a second region adjacent to the fourth region along a second direction. Also, the Si concentration in the second region is higher than the Si concentration in the third region.