Bidirectional switch element
A bidirectional switch element includes: a substrate; an Al z Ga 1-z N layer; an Al b Ga 1-b N layer; a first source electrode; a first gate electrode; a second gate electrode; a second source electrode; a p-type Al x1 Ga 1-x1 N layer; a p-type Al x2 Ga 1-x2 N layer; an Al y Ga 1-y N layer; and an Al w Ga 1-w N layer. The Al z Ga 1-z N layer is formed over the substrate. The Al b Ga 1-b N layer is formed on the Al z Ga 1-z N layer. The Al y Ga 1-y N layer is interposed between the substrate and the Al z Ga 1-z N layer. The Al w Ga 1-w N layer is interposed between the substrate and the Al y Ga 1-y N layer and has a higher C concentration than the Al y Ga 1-y N layer.
1. A bidirectional switch element comprising:
a substrate;
an Al z Ga 1-z N layer formed over the substrate, where 0≤z<1;
an Al b Ga 1-b N layer formed on the Al z Ga 1-z N layer, where 0<b<1;
a first source electrode, a first gate electrode, a second gate electrode, and a second source electrode, which are formed on the Al b Ga 1-b N layer;
a p-type Al x1 Ga 1-x N layer interposed between the first gate electrode and the Al b Ga 1-b N layer, where 0≤x 1 ≤1;
a p-type Al x2 Ga 1-x2 N layer interposed between the second gate electrode and the Al b Ga 1-b N layer, where 0≤x2≤1;
an Al y Ga 1-y N layer interposed between the substrate and the Al z Ga 1-z N layer, where 0<y<1 and z<y<b; and
an Al w Ga 1-w N layer interposed between the substrate and the Al y Ga 1-y N layer and having a higher C concentration than the Al y Ga 1-y N layer, where 0<w<1 and z<w<b.
2. The bidirectional switch element of claim 1 , wherein
an Al composition ratio y of the Al y Ga 1-y N layer is less than 0.05.
3. The bidirectional switch element of claim 1 , wherein
an Al composition ratio y of the Al y Ga 1-y N layer is smaller than an Al composition ratio w of the Al w Ga 1-w N layer, and
in the Al y Ga 1-y N layer, the Al composition ratio y decreases as a distance from the Al w Ga 1-w N layer increases along thickness of the Al y Ga 1-y N layer.
4. The bidirectional switch element of claim 1 , wherein
the Al y Ga 1-y N layer is a stack of three or more AlGaN layers having mutually different Al composition ratios.
5. The bidirectional switch element of claim 2 , wherein
an Al composition ratio w of the Al w Ga 1-w N layer is less than 0.05.
6. The bidirectional switch element of claim 5 , wherein
the Al composition ratio y of the Al y Ga 1-y N layer is less than 0.03, and
the Al composition ratio w of the Al w Ga 1-w N layer is less than 0.03.
7. The bidirectional switch element of claim 1 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
8. The bidirectional switch element of claim 1 , wherein
the Al w Ga 1-w N layer has greater thickness than the Al y Ga 1-y N layer.
9. The bidirectional switch element of claim 2 , wherein
an Al composition ratio y of the Al y Ga 1-y N layer is smaller than an Al composition ratio w of the Al w Ga 1-w N layer, and
in the Al y Ga 1-y N layer, the Al composition ratio y decreases as a distance from the Al w Ga 1-w N layer increases along thickness of the Al y Ga 1-y N layer.
10. The bidirectional switch element of claim 2 , wherein
the Al y Ga 1-y N layer is a stack of three or more AlGaN layers having mutually different Al composition ratios.
11. The bidirectional switch element of claim 3 , wherein
the Al y Ga 1-y N layer is a stack of three or more AlGaN layers having mutually different Al composition ratios.
12. The bidirectional switch element of claim 2 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
13. The bidirectional switch element of claim 3 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
14. The bidirectional switch element of claim 4 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
15. The bidirectional switch element of claim 5 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
16. The bidirectional switch element of claim 6 , wherein
the bidirectional switch element is used with the substrate electrically insulated from all of the first source electrode, the second source electrode, the first gate electrode, and the second gate electrode.
17. The bidirectional switch element of claim 2 , wherein
the Al w Ga 1-w N layer has greater thickness than the Al y Ga 1-y N layer.
18. The bidirectional switch element of claim 3 , wherein
the Al w Ga 1-w N layer has greater thickness than the Al y Ga 1-y N layer.