Compound semiconductor device and method of manufacturing the same

A compound semiconductor device comprising:

• a buffer layer formed on a conductive SiC substrate;
• an i-type GaN-based carrier transit layer formed on the buffer layer;
• a carrier supply layer formed on the carrier transit layer;
• a source electrode and a drain electrode formed on the carrier supply layer;
• and
• a gate electrode formed on the carrier supply layer between the source electrode and the drain electrode, wherein the buffer layer includes
• a first AlN layer formed on the conductive SiC substrate;
• a second AlN layer formed on the first AlN layer;
• and
• an AlxGa1-xN layer formed on the second AlN layer, in which a transition metal element is added, and in which the Al composition x is 0≦x≦1,
• wherein a first surface between the first AlN layer and the second AlN layer has greater textured roughness than a second surface between the conductive SiC substrate and the first AlN layer;
• wherein the textured roughness has a plurality of tips of different heights.