Non-polar single crystalline a-plane nitride semiconductor wafer and preparation thereof
A single crystalline a-plane nitride semiconductor wafer having no voids, bending or cracks can be rapidly and effectively prepared by hydride vapor phase epitaxy (HVPE) growth of the a-plane nitride semiconductor film on a single crystalline r-plane sapphire substrate at a temperature ranging from 950 to 1,100° C. and at a rate ranging from 30 to 300 μm/hr.
1 . A single crystalline a-plane ({11-20}-plane) nitride semiconductor wafer having a thickness of 130 μm or more.
2 . The a-plane nitride semiconductor wafer of claim 1 which has a thickness of 150 μm or more.
3 . The a-plane nitride semiconductor wafer of claim 1 which has a thickness of 300 μm or more.
4 . The a-plane nitride semiconductor wafer of claim 1 which is grown on a single crystalline r-plane ({1-102}-plane) sapphire substrate.
5 . The a-plane nitride semiconductor wafer of claim 1 which is grown by hydride vapor phase epitaxy (HVPE).
6 . The a-plane nitride semiconductor wafer of claim 1 which has a diameter of 25 mm or more.
7 . The a-plane nitride semiconductor wafer of claim 1 which has a diameter of 50.8 mm or more.
8 . The a-plane nitride semiconductor wafer of claim 4 which, after grown, is separated from the substrate and then polished.
9 . The a-plane nitride semiconductor wafer of claim 1 which has an FWHM (full width at half maximum) value of 1,000 arcsec or less in an X-ray diffraction (XRD) rocking curve.
10 . The a-plane nitride semiconductor wafer of claim 1 which has an FWHM (full width at half maximum) value of 500 arcsec or less in an X-ray diffraction (XRD) rocking curve.
11 . The a-plane nitride semiconductor wafer of claim 1 which is used as a freestanding plate in the manufacture of light-emitting diodes.
12 . The a-plane nitride semiconductor wafer of claim 1 which is composed of a nitride of at least one III-group element selected from the group consisting of Ga, Al and In.
13 . A method for preparing the a-plane nitride wafer of claim 1 which comprises growing at a rate of 30 to 300 μg/m/hr the a-plane nitride film on a single crystalline r-plane sapphire substrate heated to a temperature ranging from 950 to 1,100° C. by hydride vapor phase epitaxy (HVPE), separating the grown a-plane nitride film from the substrate, and polishing the surface thereof.
14 . The method of claim 13 , wherein the growth of the a-plane nitride film is conducted by bringing the vapor of a chloride of a III-group element and gaseous ammonia (NH 3 ) into contact with the surface of the substrate in a reactor chamber, the vapor of the chloride of the III-group element being generated through a reaction between the III-group element and gaseous hydrogen chloride.
15 . The method of claim 14 , wherein the volume ratio of the gaseous hydrogen chloride and ammonia is in the range of 1:2˜20.
16 . The method of claim 14 , wherein the volume ratio of the gaseous hydrogen chloride and ammonia is in the range of 1:2˜5.
17 . The method of claim 13 , wherein the surface of the r-plane sapphire substrate for the growth is nitridated by treating with a gas mixture of ammonia (NH 3 ) and hydrogen chloride (HCl).
18 . The method of claim 13 , wherein the growth of the a-plane nitride film continues until a desired thickness thereof is achieved.