Patent ID: 9680001
Date: 2017-06-13
CPC Classifications: H01L

Claim:
1. A nitride semiconductor device comprising: a substrate; a buffer layer formed on the substrate; a laminated body formed by two or more cycles of semiconductor layers each including a first nitride semiconductor layer and a second nitride semiconductor layer having a larger band gap than a band gap of the first nitride semiconductor layer, the first and second nitride semiconductor layers being laminated in this order on the buffer layer; a first electrode formed in a first region that continues from a side surface of the laminated body to an upper surface of the laminated body; and a second electrode formed in a second region that is a part of a region continuing from the side surface of the laminated body to the upper surface of the laminated body but is not the first region, wherein: a channel layer is formed in each of the semiconductor layers at an interface between the first nitride semiconductor layer and the second nitride semiconductor layer, a carrier concentration of the channel layer in an uppermost of the semiconductor layers is lower than a carrier concentration of each of the channel layers of the other semiconductor layers, the first nitride semiconductor layer is constituted of GaN, the second nitride semiconductor layers are constituted of AlGaN, an Al composition ratio of AlGaN constituting an uppermost layer of the second nitride semiconductor layers is lower than each Al composition ratio of AlGaN constituting the other second nitride semiconductor layers, and a number of the second nitride semiconductor layers is three or more.