Switching device
View Patent ↗A switching device provided herewith includes first to fourth semiconductor layers and a gate electrode. The second semiconductor layer is of a first conductive type or an un-dope type and located on the first semiconductor layer. A hetero junction is formed between the first and the second semiconductor layers. The third semiconductor layer is of a second conductive type and located on the second semiconductor layer. The fourth semiconductor layer is of a second conductive type and located on the third semiconductor layer. A hetero junction is formed between the third and the fourth semiconductor layers. The gate electrode electrically connected to the fourth semiconductor layer.
1. A switching device comprising:
a first semiconductor layer;
a second semiconductor layer being of a first conductive type or an undoped type and located on the first semiconductor layer, the second semiconductor layer forming a hetero junction with the first semiconductor layer;
a third semiconductor layer being of a second conductive type and located on the second semiconductor layer;
a fourth semiconductor layer being of a second conductive type and located on the third semiconductor layer, the fourth semiconductor layer forming a hetero junction with the third semiconductor layer;
a first electrode located on the second semiconductor layer;
a second electrode located on the second semiconductor layer and away from the first electrode; and
a gate electrode electrically connected to the fourth semiconductor layer and configured to switch between conduction and non-conduction between the first electrode and the second electrode.
2. A switching device of claim 1 , wherein
a second conductive type impurity concentration in the third semiconductor layer is higher than a second conductive type impurity concentration in the fourth semiconductor layer.
3. A switching device of claim 1 , wherein
the first, second, third, and fourth semiconductor layers are nitride semiconductor layers.
4. A switching device of claim 3 , wherein
the first semiconductor layer is a GaN layer,
the second semiconductor layer is an AlGaN layer being of an n-type or the undoped type,
the third semiconductor layer is a GaN layer being of a p-type,
the fourth semiconductor layer is an Al x Ga 1-x N layer, and
0<x<0.2.
5. A switching device of claim 3 , wherein
the first semiconductor layer is a GaN layer,
the second semiconductor layer is an AlGaN layer being of an n-type or the undoped type,
the third semiconductor layer is a GaN layer being of p-type, and
the fourth semiconductor layer is an In y Al x Ga 1-x-y N layer and has a bandgap wider than that in the third semiconductor layer.
6. A switching device comprising:
a first semiconductor layer;
a second semiconductor layer being of a first conductive type or an undoped type and located on the first semiconductor layer, the second semiconductor layer forming a hetero junction with the first semiconductor layer;
a third semiconductor layer being of a second conductive type and located on the second semiconductor layer;
a fourth semiconductor layer being of a second conductive type and located on the third semiconductor layer, the fourth semiconductor layer forming a hetero junction with the third semiconductor layer; and
a gate electrode electrically connected to the fourth semiconductor layer, wherein
the first, second, third, and fourth semiconductor layers are nitride semiconductor layers,
the first semiconductor layer is a GaN layer,
the second semiconductor layer is an AlGaN layer being of an n-type or the undoped type,
the third semiconductor layer is a GaN layer being of p-type, and
the fourth semiconductor layer is an In y Al x Ga 1-x-y N layer and has a bandgap wider than that in the third semiconductor layer.