SEMICONDUCTOR DEVICE

A semiconductor device includes a first electrode, a second electrode, a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type; a third semiconductor layer of the first conductivity type; a first active region; and a third electrode. The first semiconductor layer is located between the first electrode and the second electrode. The second semiconductor layer is located above the first semiconductor layer. The first active region is next to the second semiconductor layer in a second direction. The first active region includes a first upper portion and a first upper portion. An average value of a width in the second direction of the first lower portion is greater than an average value of a width in the second direction of the first upper portion. The third semiconductor layer is electrically connected with the second electrode.