Semiconductor device and manufacturing method thereof
A semiconductor device includes a GaN-based semiconductor layer that is formed on a substrate and an opening region, an electron conduction layer formed on an inner surface of the opening region, an electron supply layer that has a larger band gap than the electron conduction layer and is formed on the electron conduction layer disposed on the inner surface of the opening region, and a gate electrode formed on a side surface of the electron supply layer in the opening region. A source electrode is formed on the GaN-based semiconductor layer. A drain electrode is connected to a surface of the GaN-based semiconductor layer opposite to the source electrode.
1. A semiconductor device including:
a GaN-based semiconductor layer that is formed on a substrate and has an opening region;
an electron conduction layer formed on an inner surface of the opening region;
an electron supply layer that has a larger band gap than the electron conduction layer and is formed on the electron conduction layer disposed on the inner surface of the opening region;
a source electrode formed on the GaN-based semiconductor layer;
a drain electrode formed on a back surface of the substrate; and
an AlN layer between the electron conduction layer and the electron supply layer.
2. The semiconductor device as claimed in claim 1 , wherein: the GaN-based semiconductor layer includes a P-type GaN-based semiconductor layer;
at least the P-type GaN-based semiconductor layer is removed in the opening region; and
the electron conduction layer formed on the P-type GaN-based semiconductor layer exposed in an inner surface of the opening region.
3. The semiconductor device as claimed in claim 2 wherein
wherein the GaN-based semiconductor layer includes a first N-type GaN-based semiconductor layer and a second N-type GaN-based semiconductor layer with the P-type GaN-based semiconductor layer being interposed therebetween.
4. The semiconductor device as claimed in claim 2 , wherein the P-type GaN-based semiconductor layer is at least either a GaN layer or an AlGaN layer.
5. The semiconductor device as claimed in claim 1 , wherein:
the electron conduction layer is an In x2 Al y2 Ga (1-x2-y2) N layer;
the electron supply layer is an In X1 Al y1 Ga (1-x1-y1) N layer, and;
relationships (0≦x2, y2, x1, y1≦1) and 2.81(y1−y2)−1.50(x1−x2)>0 are satisfied.
6. The semiconductor device as claimed in claim 1 , wherein the electron conduction layer is made of either GaN or InGaN and the electron supply layer is made of an AlGaN.
7. The semiconductor device as claimed in claim 1 , wherein the electron conduction layer has a film thickness of 5 to 100 nm.
8. The semiconductor device as claimed in claim 1 , wherein the substrate is a silicon carbide (SiC) substrate, a sapphire substrate, a silicon substrate or a substrate including GaN.