Seed and seedholder combinations for high quality growth of large silicon carbide single crystals
View Patent ↗A silicon carbide seeded sublimation method is disclosed. The method includes the steps of nucleating growth on a seed crystal growth face that is between about 1° and 10° off-axis from the (0001) plane of the seed crystal while establishing a thermal gradient between the seed crystal and a source composition that is substantially perpendicular to the basal plane of the off-axis crystal.
1. A seeded sublimation method of growing large single crystals of silicon carbide with reduced defects, the method comprising:
nucleating growth on a seed crystal growth face that is between about 1° and 10° off-axis from the (0001) plane of the seed crystal;
while establishing a thermal gradient between the seed crystal and a source composition that is substantially perpendicular to the basal plane of the off-axis crystal.
2. A seeded sublimation method of growing large single crystals of silicon carbide with reduced defects, the method comprising:
establishing a major growth temperature gradient between a silicon carbide seed crystal and a silicon carbide source composition; and
positioning the seed crystal on the seed holder with the macroscopic growth face of the seed crystal at an angle of between about 70° and 89.5° with respect to the major growth gradient.
3. A method according to claim 2 comprising positioning the seed crystal on the seed holder with the macroscopic growth face of the seed crystal at an angle of between about 70° and 80° with respect to the major growth gradient.
4. A method according to claim 2 comprising establishing the major temperature gradient with a total temperature difference of between about 50 and 200° C.
5. A method according to claim 2 comprising presenting the basal plane of the seed crystal as the growth surface.
6. A method according to claim 2 comprising slicing the resulting bulk crystal into wafers.
7. A method according to claim 6 comprising polishing the sliced wafers.
8. A method according to claim 6 comprising growing an epitaxial layer of a semiconductor material on the sliced wafer.
9. A method according to claim 8 comprising growing an epitaxial layer selected from the group consisting of silicon carbide and Group III nitrides.
10. A seeded sublimation method of growing large single crystals of silicon carbide with reduced defects, the method comprising:
establishing a major growth temperature gradient between a silicon carbide seed crystal and a silicon carbide source composition;
presenting a growth face on the seed crystal that is between about 1° and 10° off axis from the (0001) plane; and
positioning the seed crystal on the seed holder with the growth face at an angle of between about 70° and 89.5° with respect to the major growth gradient.
11. A method according to claim 10 comprising establishing the major growth gradient between silicon carbide source powder and the seed crystal.
12. A method according to claim 10 comprising presenting the seed crystal on a seed holder that forms an angle of between about 70° and 89.5° with respect to the major growth gradient.
13. A method according to claim 10 comprising presenting the seed crystal on a seed holder that forms an angle of between about 70° and 80° with respect to the major growth gradient.
14. A method according to claim 10 comprising presenting the seed crystal on a seed holder that forms an angle of about 86° with respect to the major growth gradient.
15. A method according to claim 10 comprising presenting a growth face on the seed crystal that is about 4° off-axis from the (0001) plane.
16. A method according to claim 10 comprising presenting a seed crystal that has a polytype selected from the group consisting of the 4H and 6H polytypes of silicon carbide.