Epitaxial substrate for electronic device and method of producing the same
An epitaxial substrate for electronic devices is provided, which can improve vertical breakdown voltage and provides a method of producing the same. The epitaxial substrate includes a conductive SiC single crystal substrate, a buffer as an insulating layer on the SiC single crystal substrate, and a main laminate formed by epitaxially growing a plurality of Group III nitride layers on the buffer. Further, the buffer includes at least an initial growth layer in contact with the SiC single crystal substrate and a superlattice laminate having a superlattice multi-layer structure on the initial growth layer. The initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N material. Furthermore, the superlattice laminate is configured by alternately stacking a first layer made of a B a2 Al b2 Ga c2 In d2 N material and a second layer made of a B a3 Al b3 Ga c3 In d3 N material having a different band gap from the first layer.
1. An epitaxial substrate for an electronic device, comprising:
a conductive SiC single crystal substrate,
a buffer as an insulating layer on the SiC single crystal substrate, and
a main laminate formed by epitaxially growing a plurality of Group III nitride layers on the buffer,
wherein a lateral direction is a current flow direction,
the buffer includes at least an initial growth layer in contact with the SiC single crystal substrate and a superlattice laminate having a superlattice multi-layer structure on the initial growth layer,
the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0<b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material,
the superlattice laminate is configured by alternately stacking a first layer made of a B a2 Al b2 Ga c2 In d2 N (0≦a 2 ≦1, 0≦b 2 ≦1, 0≦c 2 ≦1, 0≦d 2 ≦1, a 2 +b 2 +c 2 +d 2 =1) material and a second layer made of a B 3 Al b3 Ga c3 In d3 N (0≦a 3 ≦1, 0≦b 3 ≦1, 0≦c 3 ≦1, 0≦d 3 ≦1, a 3 +b 3 +c 3 +d 3 =1) material having a different band gap from the first layer, and
at least one of the superlattice laminate and a portion of the main laminate on the buffer side has a C concentration of 1×10 18 /cm 3 or more.
2. The epitaxial substrate for an electronic device, according to claim 1 ,
wherein both the superlattice laminate and the portion of the main laminate on the buffer side has a C concentration of 1×10 18 /cm 3 or more.
3. The epitaxial substrate for an electronic device, according to claim 1 ,
wherein the first layer is made of an AlN material, and the second layer is made of an Al b3 Ga c3 N (a 3 =0, 0<b 3 ≦0.5, 0.5≦c 3 <1, d 3 =0) material.
4. The epitaxial substrate for an electronic device, according to claim 1 ,
wherein the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0.5≦b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material.
5. The epitaxial substrate for an electronic device, according to claim 1 ,
wherein the initial growth layer is made of an AlN material.
6. A method of producing an epitaxial substrate for an electronic device, the epitaxial substrate comprising:
a conductive SiC single crystal substrate,
a buffer as an insulating layer on the SiC single crystal substrate, and
a main laminate formed by epitaxially growing a plurality of Group III nitride layers on the buffer,
wherein a lateral direction is a current flow direction,
the buffer includes at least an initial growth layer in contact with the SiC single crystal substrate and a superlattice laminate having a superlattice multi-layer structure on the initial growth layer,
the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0<b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 1, a 1 +b 1 +c 1 +d 1 =1) material,
the superlattice laminate is configured by alternately stacking a first layer made of a B 2 Al b2 Ga c2 In d2 N (0≦a 2 ≦1, 0≦b 2 ≦1, 0≦c 2 ≦1, 0≦d 2 ≦1, a 1 +b 2 +c 2 +d 2 =1) material and a second layer made of a B a3 Al b3 Ga c3 In d3 N (0≦a 3 ≦1, 0≦b 3 ≦1, 0≦c 3 ≦1, 0≦d 3 ≦1, a 3 +b 3 +c 3 +d 3 =1) material having a different band gap from the first layer, and
at least one of the superlattice laminate and a portion of the main laminate on the buffer side has a C concentration of 1×10 18 /cm 3 or more.
7. The method of producing the epitaxial substrate for an electronic device, according to claim 6 ,
wherein both the superlattice laminate and the portion of the main laminate on the buffer side each has a C concentration of 1×10 18 /cm 3 or more.
8. The epitaxial substrate for an electronic device, according to claim 2 ,
wherein the first layer is made of an AlN material, and the second layer is made of an Al b3 Ga c3 N (a 3 =0, 0<b 3 ≦0.5, 0.5≦c 3 <1, d 3 =0) material.
9. The epitaxial substrate for an electronic device, according to claim 2 ,
wherein the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0.5≦b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material.
10. The epitaxial substrate for an electronic device, according to claim 3 ,
wherein the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0.5≦b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material.
11. The epitaxial substrate for an electronic device, according to claim 8 ,
wherein the initial growth layer is made of a B a1 Al b1 Ga c1 In d1 N (0≦a 1 ≦1, 0.5≦b 1 ≦1, 0≦c 1 ≦1, 0≦d 1 ≦1, a 1 +b 1 +c 1 +d 1 =1) material.
12. The epitaxial substrate for an electronic device, according to claim 2 ,
wherein the initial growth layer is made of an AlN material.
13. The epitaxial substrate for an electronic device, according to claim 3 ,
wherein the initial growth layer is made of an AlN material.
14. The epitaxial substrate for an electronic device, according to claim 8 ,
wherein the initial growth layer is made of an AlN material.