Method of fabricating group III nitride semiconductor single crystal, and method of fabricating group III nitride semiconductor single crystal substrate
View Patent ↗A method of fabricating a group III nitride semiconductor single crystal includes preparing a seed substrate which includes group III nitride semiconductor and has a crystal growth face of single index plane, and epitaxially growing the group III nitride semiconductor single crystal on the crystal growth face, wherein the group III nitride semiconductor single crystal is epitaxially grown while being surrounded by a plurality of crystal surfaces including low-index planes spontaneously formed, and the low-index planes have a structure that each of plane indices showing a crystal plane is not more than 3.
1. A method of fabricating a group III nitride semiconductor single crystal, said method comprising:
preparing a seed substrate which comprises group III nitride semiconductor and has a crystal growth face of single index plane; and
epitaxially growing the group III nitride semiconductor single crystal on the crystal growth face,
wherein the group III nitride semiconductor single crystal is epitaxially grown while being surrounded only by a plurality of crystal surfaces comprising low-index planes spontaneously formed, and
wherein the low-index planes have a structure that each of plane indices showing a crystal plane is not more than 3.
2. The method of fabricating the group III nitride semiconductor single crystal according to claim 1 , wherein the group III nitride semiconductor comprises a hexagonal nitride semiconductor, and
wherein a low-index plane of the low-index planes has a structure that when the index plane is represented as {h k l m} where all of h, k, l and m are an integer number, each of absolute values of h, k, l and m is not more than 3.
3. The method of fabricating the group III nitride semiconductor single crystal according to claim 2 , wherein the plurality of the crystal surfaces do not comprise high-index planes having a structure that any one of the plane indices showing the crystal plane is not less than 4.
4. The method of fabricating the group III nitride semiconductor single crystal according to claim 3 , wherein the group III nitride semiconductor single crystal having a maximum external diameter of not less than 15 mm is epitaxially grown.
5. The method of fabricating the group III nitride semiconductor single crystal according to claim 4 , wherein the group III nitride semiconductor single crystal is epitaxially grown by not less than 5 mm along a crystal growth direction.
6. The method of fabricating the group III nitride semiconductor single crystal according to claim 5 , wherein the group III nitride semiconductor single crystal is epitaxially grown at a crystal growth speed of not less than 300 μm/h.
7. The method of fabricating the group III nitride semiconductor single crystal according to claim 6 , wherein the seed substrate is prepared by that a periphery of the seed substrate is cleaved so that the seed substrate having sides parallel to the low-index plane is formed.
8. The method of fabricating the group III nitride semiconductor single crystal according to claim 6 , wherein the seed substrate is prepared by that a mask is installed on the seed substrate so that the crystal growth face is limited to a part of a surface of the seed substrate.
9. A method of fabricating a group III nitride semiconductor single crystal substrate, said method comprising:
cutting the group III nitride semiconductor single crystal fabricated by the method of fabricating the group III nitride semiconductor single crystal according to claim 1 by a plane vertical to a crystal growth direction so as to obtain the group III nitride semiconductor single crystal substrates.
10. The method of fabricating the group III nitride semiconductor single crystal substrate according to claim 9 , wherein the group III nitride semiconductor single crystal substrate has a quadrangular or a hexagonal shape.
11. The method of fabricating the group III nitride semiconductor single crystal according to claim 1 , wherein the low-index planes are spontaneously formed by a crystal growth.
12. The method of fabricating the group III nitride semiconductor single crystal according to claim 1 , wherein the low-index planes have a surface energy smaller than that of high-index planes in the plurality of crystal surfaces.
13. The method of fabricating the group III nitride semiconductor single crystal according to claim 1 , wherein the single crystal has a thickness substantially equal to a diameter of the seed substrate.
14. The method of fabricating the group III nitride semiconductor single crystal according to claim 1 , wherein the seed substrate for growing an ingot of the group III nitride semiconductor single crystal is cleaved to form the ingot surrounded by the low-index planes on the seed substrate.