Nitride semiconductor device

A nitride semiconductor device comprising:

• a first nitride semiconductor layer formed of GaN;
• a second nitride semiconductor layer formed on the first nitride semiconductor layer of (InTAl1-T)SGa1-SN (0<S≦1, 0<T≦1);
• a third nitride semiconductor layer formed on the second nitride semiconductor layer of (InYAl1-Y)XGa1-XN (0<X≦1, 0≦Y<1), an In composition ratio Y of the third nitride semiconductor layer being less than an In composition ratio T of the second nitride semiconductor layer;
• a fourth nitride semiconductor layer formed on the third nitride semiconductor layer of GaN or InPGaQN (0<P<1, 0<Q<1);
• a fifth nitride semiconductor layer formed on the fourth nitride semiconductor layer of InUAlWGaVN (0≦U<1, 0≦V<1, 0<W≦1, U+V+W=1);
• a gate electrode formed on the fifth nitride semiconductor layer;
• and
• a source electrode and a drain electrode formed on the fifth nitride semiconductor layer on both sides of the gate electrode.

A nitride semiconductor device comprising:

• a first nitride semiconductor layer formed of GaN;
• a second nitride semiconductor layer formed on the first nitride semiconductor layer of (InTAl1-T)SGa1-SN (0<S≦1, 0<T≦1);
• a third nitride semiconductor layer formed on the second nitride semiconductor layer of (InYAl1-Y)XGa1-XN (0<X≦1, 0≦Y<1), an In composition ratio Y of the third nitride semiconductor layer being less that an In composition ratio T of the second nitride semiconductor layer;
• a fourth nitride semiconductor layer formed on the third nitride semiconductor layer of GaN or InPGaQN (0<P<1, 0<Q<1);
• a fifth nitride semiconductor layer formed on the fourth nitride semiconductor layer of InUAlWGaVN (0≦U<1, 0≦V<1, 0<W≦1, U+V+W=1);
• and
• an anode electrode and a cathode electrode formed on the fifth nitride semiconductor layer.

A nitride semiconductor device comprising:

• a first nitride semiconductor layer formed of GaN;
• a second nitride semiconductor layer formed on the first nitride semiconductor layer of (InTAl1-T)SGa1-SN (0<S≦1, 0<T≦1);
• a third nitride semiconductor layer formed on the second nitride semiconductor layer of (InYAl1-Y)XGa1-XN (0<X≦1, 0≦Y<1), an In composition ratio Y of the third nitride semiconductor layer being less than an In composition ratio T of the second nitride semiconductor layer;
• a fourth nitride semiconductor layer formed on the third nitride semiconductor layer of GaN or InPGaQN (0<P<1, 0<Q<1);
• a fifth nitride semiconductor layer formed of non-doped or n-type AlUGa1-UN (0<U≦1);
• a sixth nitride semiconductor layer formed on the fifth nitride semiconductor layer of non-doped or n-type nitride semiconductor;
• a seventh nitride semiconductor layer formed on the sixth nitride semiconductor layer of InVAlZGa1-V-ZN (0<V≦1, 0<Z<1);
• a gate electrode formed in a recess structure having a bottom face which arrives at the sixth nitride semiconductor layer;
• and
• a source electrode and a drain electrode formed on the fifth nitride semiconductor layer, the sixth nitride semiconductor layer, or the seventh nitride semiconductor layer so as to sandwich the gate electrode therebetween.