Nitride semiconductor epitaxial substrate
There is provided a nitride semiconductor epitaxial substrate having a channel layer, a spacer layer, and an electron supply layer that are stacked in this order. The channel layer is GaN. The spacer layer is Al a Ga 1-a N (0<a<0.5). The electron supply layer is Al x ln y Ga 1-x-y N (0<x+y≤1). The spacer layer has a thickness of two molecular layers or less.
1. A nitride semiconductor epitaxial substrate, comprising a channel layer, a spacer layer, and an electron supply layer in this order, wherein
the channel layer is GaN,
the spacer layer is Al a Ga 1-a N(0<a<0.5),
the electron supply layer is Al x In y Ga 1-x-y N 0.1≤x≤0.3 and y=0), and
the spacer layer has a thickness of one or two molecular layers wherein the thickness of one molecular layer is 0.25 nm.
2. The nitride semiconductor HEMT using the nitride semiconductor epitaxial substrate according to claim 1 .