Compound semiconductor substrate and fabrication method therefor, compound semiconductor device and fabrication method therefor, power supply apparatus and high-output amplifier
A compound semiconductor substrate includes a substrate, a channel layer provided over the substrate, a nitride semiconductor layer provided over the channel layer, and a barrier layer provided on the nitride semiconductor layer. The length of the c axis of the nitride semiconductor layer is 0.4990 nm or more.
1. A compound semiconductor substrate, comprising:
a substrate;
a channel layer provided over the substrate;
a spacer layer provided over the channel layer; and
a barrier layer provided on the spacer layer; wherein
a length of a c axis of the spacer layer is 0.4990 nm or more, and
the spacer layer have a higher Al composition than that of the barrier layer.
2. The compound semiconductor substrate according to claim 1 , wherein the spacer layer contains AlN.
3. The compound semiconductor substrate according to claim 1 , wherein the barrier layer contains In X1 Al y1 Ga 1-x1-y1 N (0<x1<0.20, 0<y1≤1).
4. The compound semiconductor substrate according to claim 1 , wherein the channel layer contains GaN.
5. The compound semiconductor substrate according to claim 1 , wherein a thickness of the spacer layer is 2 nm or less.
6. The compound semiconductor substrate according to claim 1 , wherein an arithmetical average roughness Ra of a surface of the barrier layer is 0.25 nm or less.
7. The compound semiconductor substrate according to claim 1 , further comprising a cap layer provided on the barrier layer.
8. The compound semiconductor substrate according to claim 7 , wherein the cap layer contains In x2 Al y2 Ga 1-x2-y2 N (0<x2<0.1, 0<y2≤0.05).
9. A compound semiconductor device, comprising:
a substrate;
a channel layer provided over the substrate;
a spacer layer provided over the channel layer;
a barrier layer provided on the spacer layer; and
a gate electrode, a source electrode and a drain electrode provided over the barrier layer; wherein
a length of a c axis of the spacer layer is 0.4990 nm or more, and
the spacer layer have a higher Al composition than that of the barrier layer.
10. The compound semiconductor device according to claim 9 , wherein the spacer layer contains AlN.
11. The compound semiconductor device according to claim 9 , wherein the barrier layer contains In X1 Al y1 Ga 1-x1-y1 N (0<x1<0.20, 0<y1≤1).
12. A power supply apparatus, comprising:
a transistor chip; wherein
the transistor chip includes:
a substrate;
a channel layer provided over the substrate;
a spacer layer provided over the channel layer;
a barrier layer provided on the spacer layer; and
a gate electrode, a source electrode and a drain electrode provided over the barrier layer; wherein
a length of a c axis of the spacer layer is 0.4990 nm or more, and
the spacer layer have a higher Al composition than that of the barrier layer.
13. A high-output amplifier, comprising:
an amplifier that amplifies an inputting signal; wherein
the amplifier includes a transistor chip;
the transistor chip includes:
a substrate;
a channel layer provided over the substrate;
a spacer layer provided over the channel layer;
a barrier layer provided on the spacer layer; and
a gate electrode, a source electrode and a drain electrode provided over the barrier layer; wherein
a length of a c axis of the spacer layer is 0.4990 nm or more, and
the spacer layer have a higher Al composition than that of the barrier layer.