GaN semiconductor device comprising carbon and iron

A semiconductor device comprising:

• a substrate;
• a first GaN layer on the substrate and containing carbon;
• a second GaN layer on the first GaN layer and containing Fe and carbon;
• a third GaN layer on the second GaN layer and containing Fe and carbon;
• and
• an electron supply layer on the third GaN layer and having a larger band gap than GaN,
• wherein an Fe concentration of the third GaN layer gradually decreases from an Fe concentration of the second GaN layer from the second GaN layer toward the electron supply layer and is higher than 1×1015 cm−3 at a position of 100 nm deep from a bottom end of the electron supply layer,
• a top end of the first GaN layer is deeper than 800 nm from the bottom end of the electron supply layer, and
• carbon concentrations of the second and third GaN layers are lower than a carbon concentration of the first GaN layer, and
• the Fe concentration of the second GaN layer is equal to or lower than 5×1017 cm−3.

A semiconductor device comprising:

• a substrate;
• a first GaN layer on the substrate and containing carbon;
• a second GaN layer on the first GaN layer and containing Fe and carbon;
• a third GaN layer on the second GaN layer and containing Fe and carbon;
• and
• an electron supply layer on the third GaN layer and having a larger band gap than GaN,
• wherein an Fe concentration of the third GaN layer gradually decreases from an Fe concentration of the second GaN layer from the second GaN layer toward the electron supply layer and is higher than 1×1015 cm−3 at a position of 100 nm deep from a bottom end of the electron supply layer,
• a top end of the first GaN layer is deeper than 500 nm from the bottom end of the third GaN layer, and
• a top end of the second GaN layer is deeper than 300 nm from the bottom end of the electron supply layer, and
• carbon concentrations of the second and third GaN layers are lower than a carbon concentration of the first GaN layer.

A semiconductor device comprising:

• a substrate;
• a first GaN layer on the substrate and containing Fe and carbon;
• a second GaN layer on the first GaN layer and containing Fe and carbon;
• and
• an electron supply layer on the second GaN layer and having a larger band gap than GaN,
• wherein a Fe concentration of the second GaN layer gradually decreases from an Fe concentration of the first GaN layer from the first GaN layer toward the electron supply layer and is higher than 1×1015 cm−3 at a position of 100 nm deep from a bottom end of the electron supply layer,
• a carbon concentration of the first GaN layer is equal to or higher than 1×1017 cm−3,
• a top end of the first GaN layer is deeper than 800 nm from the bottom end of the electron supply layer, and
• a carbon concentration of the second GaN layer is lower than the carbon concentration of the first GaN layer.

A semiconductor device comprising:

• a substrate;
• a GaN layer on the substrate and containing Fe and carbon;
• and
• an electron supply layer on the GaN layer and having a larger band gap than GaN,
• wherein a Fe concentration of the GaN layer at a position of 100 nm deep from a bottom end of the electron supply layer is higher than 1×1015 cm−3,
• the GaN layer includes a first region located between the bottom end of the electron supply layer and a position of 800 nm deep from the bottom end of the electron supply layer, and a second region located deeper than 800 nm from the bottom end of the electron supply layer,
• a carbon concentration of the first region is lower than 2×1016 cm−3, and
• a carbon concentration of the second region is higher than 2×1016 cm−3.