Nitride crystal, nitride crystal substrate, epilayer-containing nitride crystal substrate, semiconductor device and method of manufacturing the same

1. An epilayer-containing nitride crystal substrate comprising:

one or more semiconductor layer(s) formed by epitaxial growth on at least one of main surface sides of a nitride crystal substrate formed of a nitride crystal, wherein,

in connection with plane spacing of arbitrary specific parallel crystal lattice planes of the nitride crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while X-ray diffraction conditions of said specific parallel crystal lattice planes being satisfied, a uniform distortion at a surface layer of said crystal represented by a value of |d 1 −d 2 |/d 2 obtained from said plane spacing d 1 at said X-ray penetration depth of 0.3 mm and said plane spacing d 2 at the X-ray penetration depth of 5 mm is equal to or lower than 2.1×10 −3 .

2. An epilayer-containing nitride crystal substrate comprising:

one or more semiconductor layer(s) formed by epitaxial growth on at least one of main surface sides of a nitride crystal substrate formed of a nitride crystal, wherein,

on a diffraction intensity profile of arbitrary specific parallel crystal lattice planes of the nitride crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while X-ray diffraction conditions of said specific parallel crystal lattice planes being satisfied, an irregular distortion at a surface layer of said crystal represented by a value of |v 1 −v 2 | obtained from a half value width v 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 mm and a half value width v 2 of the diffraction intensity peak at said X-ray penetration depth of 5 mm is equal to or lower than 150 arcsec.

3. An epilayer-containing nitride crystal substrate comprising:

one or more semiconductor layer(s) formed by epitaxial growth on at least one of main surface sides of a nitride crystal substrate formed of a nitride crystal, wherein,

on a rocking curve measured by varying an X-ray penetration depth from a surface of the nitride crystal in connection with X-ray diffraction of arbitrary specific parallel crystal lattice planes of said crystal, a plane orientation deviation of said specific parallel crystal lattice planes represented by a value of |w 1 −w 2 | obtained from a half value width w 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 mm and a half value width w 2 of the diffraction intensity peak at said X-ray penetration depth of 5 mm is equal to or lower than 400 arcsec.

4. A method of manufacturing an epilayer-containing nitride crystal substrate according to claim 1 , comprising the steps of:

selecting, as said nitride crystal substrate, nitride crystal configured such that, in connection with plane spacing of arbitrary specific parallel crystal lattice planes of said crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while satisfying X-ray diffraction conditions of said specific parallel crystal lattice plane, a uniform distortion at a surface layer of said crystal represented by a value of |d 1 −d 2 |/d 2 obtained from said plane spacing d 1 at said X-ray penetration depth of 0.3 mm and said plane spacing d 2 at the X-ray penetration depth of 5 mm is equal to or lower than 2.1×10 −3 ; and

epitaxially growing one or more semiconductor layer(s) on at least one of main surface sides of said substrate.

5. A method of manufacturing an epilayer-containing nitride crystal substrate according to claim 2 , comprising the steps of:

selecting, as said nitride crystal substrate, nitride crystal configured such that, on a diffraction intensity profile of arbitrary specific parallel crystal lattice planes of the crystal obtained from X-ray diffraction measurement performed with variation of X-ray penetration depth from a surface of said crystal while X-ray diffraction conditions of said specific parallel crystal lattice planes being satisfied, an irregular distortion at a surface layer of said crystal represented by a value of |v 1 −v 2 | obtained from a half value width v 1 of a diffraction intensity peak at the X-ray penetration depth of 0.3 mm and a half value width v 2 of the diffraction intensity peak at the X-ray penetration depth of 5 mm is equal to or lower than 150 arcsec; and

epitaxially growing one or more semiconductor layer(s) on at least one of main surface sides of said substrate.

6. A method of manufacturing an epilayer-containing nitride crystal substrate according to claim 3 , comprising the steps of:

selecting, as said nitride crystal substrate, nitride crystal configured such that, on a rocking curve measured by varying an X-ray penetration depth from a surface of said nitride crystal in connection with X-ray diffraction of arbitrary specific parallel crystal lattice planes of said crystal, a plane orientation deviation of said specific parallel crystal lattice planes represented by a value of |w 1 −w 2 | obtained from a half value width w 1 of a diffraction intensity peak at said X-ray penetration depth of 0.3 mm and a half value width w 2 of the diffraction intensity peak at said X-ray penetration depth of 5 mm is equal to or lower than 400 arcsec; and

epitaxially growing one or more semiconductor layer(s) on at least one of main surface sides of said substrate.