Semiconductor substrate, semiconductor device and method of manufacturing the semiconductor device

A semiconductor substrate comprising:

• a silicon-based substrate;
• a buffer layer provided on the silicon-based substrate and comprised of a nitride semiconductor containing boron;
• and
• an operation layer formed on the buffer layer,
• wherein the buffer layer has a stacked body comprising of three or more layers, and
• a concentration of boron in the stacked body gradually decreases toward a side of the operation layer from a side of the silicon-based substrate.

A method of manufacturing a semiconductor device comprising:

• forming a buffer layer comprised of a nitride semiconductor on a silicon-based substrate, the buffer layer having a stacked body comprising of three or more layers;
• and
• forming an operation layer on the buffer layer,
• wherein the step of forming the buffer layer comprises a stage in which boron is introduced into the buffer layer such that a concentration of boron in the buffer layer gradually decreases toward a side of the operation layer from a side of the silicon-based substrate.