Semiconductor device, fabrication method for semiconductor device, power supply apparatus and high-frequency amplifier

A power supply apparatus, comprising:

• a transistor;
• wherein
• the transistor includes:
• a p-type back barrier layer provided over a substrate and formed from a p-type nitride semiconductor in which Mg or Zn is doped;
• a nitride semiconductor stacked structure provided over the p-type back barrier layer, the nitride semiconductor stacked structure including an electron transit layer and an electron supply layer;
• a source electrode, a drain electrode and a gate electrode provided over the nitride semiconductor stacked structure, and
• a groove extending to the p-type back barrier layer.

A high-frequency amplifier, comprising:

• an amplifier to amplify an input signal;
• the amplifier to include a transistor;
• the transistor including:
• a p-type back barrier layer provided over a substrate and formed from a p-type nitride semiconductor in which Mg or Zn is doped;
• a nitride semiconductor stacked structure provided over the p-type back barrier layer, the nitride semiconductor stacked structure including an electron transit layer and an electron supply layer;
• a source electrode, a drain electrode and a gate electrode provided over the nitride semiconductor stacked structure;
• and
• a groove extending to the p-type back barrier layer.

A fabrication method for a semiconductor device, comprising:

• forming a p-type back barrier layer from a p-type nitride semiconductor in which Mg or Zn is doped over a substrate;
• forming a nitride semiconductor stacked structure including an electron transit layer and an electron supply layer over the p-type back barrier layer;
• forming a source electrode, a drain electrode and a gate electrode over the nitride semiconductor stacked structure;
• forming a groove extending to the p-type back barrier layer;
• and
• performing an anneal process for desorbing hydrogen from the p-type back barrier layer through the groove to activate the p-type back barrier layer.