Semiconductor device and method for manufacturing the same

A method for manufacturing a semiconductor device, comprising the following steps:

• (a) providing a substrate, wherein the substrate is an n+-type doped silicon carbide substrate, an n-type doped silicon carbide substrate, or a p-type doped silicon carbide substrate;
• (b) forming a buffer layer on the substrate, wherein the buffer layer contains a doped gallium nitride, and has a breakdown electric field of greater than or equal to 80 V/μm;
• (c) forming an active region on the buffer layer, comprising forming a channel layer and forming a barrier layer on the channel layer, wherein the channel layer contains an undoped or unintentionally doped gallium nitride, and the barrier layer contains an undoped or unintentionally doped aluminum gallium nitride;
• and
• (d) forming a source, a gate, and a drain on the active region, wherein the gate is arranged between the source and the drain.