Nitride semiconductor device, nitride semiconductor wafer, and method for manufacturing nitride semiconductor layer
View Patent ↗According to one embodiment, a nitride semiconductor device includes: a stacked foundation layer, and a functional layer. The stacked foundation layer is formed on an AlN buffer layer formed on a silicon substrate. The stacked foundation layer includes AlN foundation layers and GaN foundation layers being alternately stacked. The functional layer includes a low-concentration part, and a high-concentration part provided on the low-concentration part. A substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers includes first and second portions, and a third portion provided between the first and second portions. The third portion has a Si concentration not less than 5×10 18 cm −3 and has a thickness smaller than a sum of those of the first and second portions.
1. A nitride semiconductor device comprising:
a stacked foundation layer formed on an AlN buffer layer formed on a silicon substrate, the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers; and
a functional layer including:
a low-concentration part provided on the stacked foundation layer, the low-concentration part including a nitride semiconductor and having a Si concentration less than 1×10 18 cm −3 ; and
a high-concentration part provided on the low-concentration part and having a Si concentration not less than 1×10 18 cm −3 ,
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5×10 18 cm −3 ;
a second portion having a Si concentration less than 5×10 18 cm −3 ; and
a third portion being provided between the first portion and the second portion, the third portion having a Si concentration not less than 5×10 18 cm −3 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
2. The device according to claim 1 , wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
3. The device according to claim 1 , wherein
all of the GaN foundation layers except for the substrate-side GaN foundation layer among the plurality of GaN foundation layers have a Si concentration less than 5×10 18 cm −3 .
4. The device according to claim 1 , wherein
a thickness of the high-concentration part is not less than 1.5 micrometers and not more than 4 micrometers.
5. The device according to claim 1 , wherein
the functional layer further includes:
a light emitting part provided on the high-concentration part and having a plurality of barrier layers and a plurality of well layers, the each of the well layers being provided between the barrier layers; and
a p-type semiconductor layer provided on the light emitting part, the p-type semiconductor layer including a nitride semiconductor and containing at least one of Mg, Zn and C.
6. A nitride semiconductor device comprising
a functional layer formed on an AlN buffer layer formed on a silicon substrate, the functional layer including:
a plurality of low-concentration parts including a nitride semiconductor and having a Si concentration less than 5×10 18 cm −3 ; and
a plurality of high-concentration parts having a Si concentration not less than 5×10 18 cm −3 , the low-concentration parts being alternately stacked with the high-concentration parts,
a thickness of each of the high-concentration parts being smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si α N β (0<α, 0<β).
7. The device according to claim 6 , wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
8. The device according to claim 6 , further comprising
a stacked foundation layer formed on the AlN buffer layer and under the functional layer,
the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers, and
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5×10 18 cm −3 ;
a second portion having a Si concentration less than 5×10 18 cm −3 ;and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5×10 18 cm −3 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
9. A nitride semiconductor wafer comprising:
a silicon substrate;
an AlN buffer layer provided on the silicon substrate;
a stacked foundation layer provided on the AlN buffer layer, the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers; and
a functional layer including
a low-concentration part provided on the stacked foundation layer, the low-concentration part including a nitride semiconductor and having a Si concentration less than 5×10 18 cm −3 , and
a high-concentration part provided on the low-concentration part and having a Si concentration not less than 5×10 18 cm −3 ,
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5×10 18 cm −3 ;
a second portion having a Si concentration less than 5×10 18 cm −3 ; and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5×10 18 cm −3 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
10. The wafer according to claim 9 , wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
11. The wafer according to claim 9 , wherein
all of the GaN foundation layers except for the substrate-side GaN foundation layer among the plurality of GaN foundation layers have a Si concentration less than 5×10 18 cm −3 .
12. The wafer according to claim 9 , wherein
a thickness of the high-concentration part is not less than 1.5 micrometers and not more than 4 micrometers.
13. The wafer according to claim 9 , wherein
the functional layer further includes:
a light emitting part provided on the high-concentration part and having a plurality of barrier layers and a plurality of well layers, the each of the well layers being provided between the barrier layers; and
a p-type semiconductor layer provided on the light emitting part, the p-type semiconductor layer including a nitride semiconductor and containing at least one of Mg, Zn and C.
14. A nitride semiconductor wafer comprising:
a silicon substrate;
an AlN buffer layer provided on the silicon substrate; and
a functional layer provided on the AlN buffer layer,
the functional layer including:
a plurality of low-concentration parts including a nitride semiconductor and having a Si concentration less than 5×10 18 cm −3 ; and
a plurality of high-concentration parts having a Si concentration not less than 5×10 18 cm −3 , the low-concentration parts being alternately stacked with the high-concentration parts,
a thickness of each of the high-concentration parts is smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si α N β (0<α, 0<β).
15. The wafer according to claim 14 , wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
16. The wafer according to claim 14 , further comprising
a stacked foundation layer formed on the AlN buffer layer and under the functional layer,
the stacked foundation layer including a plurality of AlN foundation layers and a plurality of GaN foundation layers being alternately stacked with the AlN foundation layers, and
a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers including:
a first portion having a Si concentration less than 5×10 18 cm −3 ;
a second portion having a Si concentration less than 5×10 18 cm −3 ;and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5×10 18 cm −3 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
17. A method for manufacturing a nitride semiconductor layer comprising:
forming a stacked foundation layer by alternately stacking a plurality of AlN foundation layers and a plurality of GaN foundation layers on an AlN buffer layer provided on a silicon substrate; and
forming a functional layer by forming a low-concentration part on the stacked foundation layer and forming a high-concentration part on the low-concentration part, the low-concentration part including a nitride semiconductor and having a Si concentration less than 5×10 18 cm −3 , the high-concentration part having a Si concentration not less than 5×10 18 cm −3 ,
in formation of a substrate-side GaN foundation layer closest to the silicon substrate among the plurality of GaN foundation layers, the forming the stacked foundation layer includes forming
a first portion having a Si concentration less than 5×10 18 cm −3 ,
a second portion having a Si concentration less than 5×10 18 cm −3 and
a third portion provided between the first portion and the second portion, the third portion having a Si concentration not less than 5×10 18 cm −3 and having a thickness smaller than a sum of a thickness of the first portion and a thickness of the second portion.
18. The method according to claim 17 , wherein
the thickness of the third portion is not less than 0.1 nanometers and not more than 50 nanometers.
19. A method for manufacturing a nitride semiconductor layer comprising:
forming a functional layer on an AlN buffer layer formed on a silicon substrate,
the forming the functional layer including repeating a process a plurality of times, the process including:
forming a low-concentration part including a nitride semiconductor and having a Si concentration less than 5×10 18 cm −3 ; and
forming a high-concentration part having a Si concentration not less than 5×10 18 cm −3 , and
a thickness of each of the high-concentration parts is smaller than a thickness of each of the low-concentration parts,
each of the high-concentration parts includes Si α N β (0<α, 0<β).
20. The method according to claim 19 , wherein
the thickness of each of the high-concentration parts is not less than 0.1 nanometers and not more than 50 nanometers.
21. The device according to claim 1 , wherein the third portion includes Si α N β (0<α, 0<β).
22. The wafer according to claim 9 , wherein the third portion includes Si α N β (0<α, 0<β).
23. The wafer according to claim 17 , wherein the third portion includes Si α N β (0<α, 0<β).
24. The device according to claim 6 , wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
25. The device according to claim 6 , wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.
26. The wafer according to claim 14 , wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
27. The wafer according to claim 14 , wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.
28. The method according to claim 19 , wherein the thickness of each of the low-concentration parts is not less than 50 nanometers and not more than 500 nanometers.
29. The method according to claim 19 , wherein the thickness of each of the low-concentration parts is not less than 300 nanometers and not more than 500 nanometers.