Compound semiconductor device and manufacturing method of the same

A method for manufacturing a compound semiconductor device, the method comprising:

• providing a first compound semiconductor layer having a band gap;
• forming a second compound semiconductor layer having a band gap larger than the band gap of the first compound semiconductor layer on an upper side of the first compound semiconductor layer;
• forming a p-type third compound semiconductor layer on an upper side of the second compound semiconductor layer;
• forming an electrode on an upper side of the second compound semiconductor layer through the third compound semiconductor layer;
• forming a fourth compound semiconductor layer having a band gap smaller than the band gap of the second compound semiconductor layer so as to be in contact with the third compound semiconductor layer at an upper side of the second compound semiconductor layer;
• and
• forming a fifth compound semiconductor layer having a band gap larger than the band gap of the fourth compound semiconductor layer so as to be in contact with the third compound semiconductor layer at an upper side of the fourth compound semiconductor layer.

A power supply circuit comprising:

• a transformer, and a low-voltage circuit and a high-voltage circuit across the transformer,
• wherein the high-voltage circuit has a transistor, and
• the transistor comprises:
• a first compound semiconductor layer;
• a second compound semiconductor layer formed on an upper side of the first compound semiconductor layer and having a band gap larger than the band gap of the first compound semiconductor layer;
• a conductive p-type third compound semiconductor layer formed on an upper side of the second compound semiconductor layer;
• an electrode formed on an upper side of the second compound semiconductor layer through the third compound semiconductor layer;
• a fourth compound semiconductor layer formed so as to be in contact with the third compound semiconductor layer at an upper side of the second compound semiconductor layer and having a band gap smaller than the band gap of the second compound semiconductor layer;
• and
• a fifth compound semiconductor layer formed so as to be in contact with the third compound semiconductor layer at an upper side of the fourth compound semiconductor layer and having a band gap larger than the band gap of the fourth compound semiconductor layer.

A high frequency amplifier which amplifies and outputs a high frequency voltage input, the high frequency amplifier comprising:

• a transistor,
• wherein the transistor comprises:
• a first compound semiconductor layer;
• a second compound semiconductor layer formed on an upper side of the first compound semiconductor layer and having a band gap larger than the band gap of the first compound semiconductor layer;
• a conductive p-type third compound semiconductor layer formed on an upper side of the second compound semiconductor layer;
• an electrode formed on an upper side of the second compound semiconductor layer through the third compound semiconductor layer;
• a fourth compound semiconductor layer formed so as to be in contact with the third compound semiconductor layer at an upper side of the second compound semiconductor layer and having a band gap smaller than the band gap of the second compound semiconductor layer;
• and
• a fifth compound semiconductor layer formed so as to be in contact with the third compound semiconductor layer at an upper side of the fourth compound semiconductor layer and having a band gap larger than the band gap of the fourth compound semiconductor layer.