A semiconductor apparatus includes a semiconductor substrate including a semiconductor device. The semiconductor device includes a first n-type buffer layer, a second n-type buffer layer, and a first p-type semiconductor region. A first maximum peak concentration of first n-type carriers contained in the first n-type buffer layer is smaller than a second maximum peak concentration of second n-type carriers contained in the second n-type buffer layer. The first p-type semiconductor region is formed in the first n-type buffer layer. The first p-type semiconductor region has a narrower width than the first n-type buffer layer.