Semiconductor device and field effect transistor
First Claim
1. A semiconductor device comprises:
- a substrate;
a first n-type semiconductor layer;
a second n-type semiconductor layer;
a p-type semiconductor layer;
a third n-type semiconductor layer;
a drain electrode;
a source electrode; and
a gate electrode, whereinthe first n-type semiconductor layer, the second n-type semiconductor layer, the p-type semiconductor layer, and the third n-type semiconductor layer are laminated at the upper side of the substrate in this order,the drain electrode is in ohmic-contact with the first n-type semiconductor layer directly or via the substrate,the source electrode is in ohmic-contact with the third n-type semiconductor layer,an opening portion to be filled that extends from an upper surface of the third n-type semiconductor layer to an upper part of the second n-type semiconductor layer is formed at a part of the p-type semiconductor layer and a part of the third n-type semiconductor layer,the gate electrode is arranged so as to fill the opening portion to be filled and is in contact with an upper surface of the second n-type semiconductor layer, side surfaces of the p-type semiconductor layer, and side surfaces of the third n-type semiconductor layer at inner surfaces of the opening portion to be filled, andthe second n-type semiconductor layer has composition that changes from a drain electrode side toward a source electrode side in a direction perpendicular to a plane of the substrate and contains donor impuritywherein the second n-type semiconductor layer has composition represented by AlxGa1-xN (0≦
x<
1), and a relationship between an Al composition ratio at an interface at a first n-type semiconductor layer side x0>
0) and an Al composition interface at a p-type semiconductor layer side xA (xA≧
0) satisfies the following equation;
x0>
xA.
3 Assignments
0 Petitions
Accused Products
Abstract
Provided is a semiconductor device in which the trade-off between the withstand voltage and the on-resistance is improved and the performance is increased. A semiconductor device comprises a substrate 1, a first n-type semiconductor layer 21′, a second n-type semiconductor layer 23, a p-type semiconductor layer 24, and a third n-type semiconductor layer 25′, wherein the first n-type semiconductor layer 21′, the second n-type semiconductor layer 23, the p-type semiconductor layer 24, and the third n-type semiconductor layer 25′ are laminated at the upper side of the substrate 1 in this order. The drain electrode 13 is in ohmic-contact with the first n-type semiconductor layer 21′ and the source electrode 12 is in ohmic-contact with the third n-type semiconductor layer 25′. A gate electrode 14 is arranged so as to fill an opening portion to be filled that extends from the third n-type semiconductor layer 25′ to the second n-type semiconductor layer 23, and the gate electrode 14 is in contact with the upper surface of the second n-type semiconductor layer 23, the side surfaces of the p-type semiconductor layer 24, and the side surfaces of the third n-type semiconductor layer 25′. The second n-type semiconductor layer 23 has composition that changes from the drain electrode 13 side toward the source electrode 12 side in the direction perpendicular to the plane of the substrate 1 and contains donor impurity.
9 Citations
17 Claims
-
1. A semiconductor device comprises:
-
a substrate; a first n-type semiconductor layer; a second n-type semiconductor layer; a p-type semiconductor layer; a third n-type semiconductor layer; a drain electrode; a source electrode; and a gate electrode, wherein the first n-type semiconductor layer, the second n-type semiconductor layer, the p-type semiconductor layer, and the third n-type semiconductor layer are laminated at the upper side of the substrate in this order, the drain electrode is in ohmic-contact with the first n-type semiconductor layer directly or via the substrate, the source electrode is in ohmic-contact with the third n-type semiconductor layer, an opening portion to be filled that extends from an upper surface of the third n-type semiconductor layer to an upper part of the second n-type semiconductor layer is formed at a part of the p-type semiconductor layer and a part of the third n-type semiconductor layer, the gate electrode is arranged so as to fill the opening portion to be filled and is in contact with an upper surface of the second n-type semiconductor layer, side surfaces of the p-type semiconductor layer, and side surfaces of the third n-type semiconductor layer at inner surfaces of the opening portion to be filled, and the second n-type semiconductor layer has composition that changes from a drain electrode side toward a source electrode side in a direction perpendicular to a plane of the substrate and contains donor impurity wherein the second n-type semiconductor layer has composition represented by AlxGa1-xN (0≦
x<
1), and a relationship between an Al composition ratio at an interface at a first n-type semiconductor layer side x0>
0) and an Al composition interface at a p-type semiconductor layer side xA (xA≧
0) satisfies the following equation;
x0>
xA. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification