NITRIDE SEMICONDUCTOR DEVICE, NITRIDE SEMICONDUCTOR WAFER, AND METHOD FOR MANUFACTURING NITRIDE SEMICONDUCTOR LAYER

摘要

According to one embodiment, a nitride semiconductor device includes a foundation layer, a first stacked intermediate layer, and a functional layer. The foundation layer includes an AlN buffer layer formed on a substrate. The first stacked intermediate layer is provided on the foundation layer. The first stacked intermediate layer includes a first AlN intermediate layer provided on the foundation layer, a first AlGaN intermediate layer provided on the first AlN intermediate layer, and a first GaN intermediate layer provided on the first AlGaN intermediate layer. The functional layer is provided on the first stacked intermediate layer. The first AlGaN intermediate layer includes a first step layer in contact with the first AlN intermediate layer. An Al composition ratio in the first step layer decreases stepwise in a stacking direction from the first AlN intermediate layer toward the first step layer.