C-PLANE SAPPHIRE METHOD AND APPARATUS
A method and apparatus for the production of C-plane single crystal sapphire is disclosed. The method and apparatus may use edge defined film-fed growth techniques for the production of single crystal material exhibiting low polycrystallinity and/or low dislocation density.
1 . (canceled)
2 . A single crystal growth apparatus, comprising:
a die with a die opening;
a first region of the apparatus adjacent to the die opening, wherein the first region is configured to exhibit a first thermal gradient;
a second region of the apparatus configured to exhibit a second thermal gradient, wherein the first region is between the die and the second region; and
wherein the first thermal gradient is greater than the second thermal gradient.
3 . The apparatus of claim 1 , wherein the first thermal gradient is at least twice the second thermal gradient.
4 . The apparatus of claim 1 , wherein a heat shield is disposed adjacent to the first region.
5 . The apparatus of claim 1 , wherein the second region of the apparatus does not include a heat shield.
6 . The apparatus of claim 1 , further comprising a heater disposed to supply heat to the second region of the apparatus.
7 . The apparatus of claim 1 , wherein the first region of the apparatus does not include a heater.
8 . The apparatus of claim 1 , wherein the first thermal gradient extends along a path of crystal growth for a distance of at least 1 cm.
9 . The apparatus of claim 1 , further comprising an enclosure disposed above the die, wherein the enclosure includes the second region of the apparatus.
10 . The apparatus of claim 9 , wherein a bottom of the enclosure is adjacent to a top of the die.
11 . A single crystal growth apparatus, comprising:
a die with a die opening;
a first region of the apparatus adjacent to the die opening;
an enclosure disposed above the die; and
a heater disposed above the first region, wherein an elevation of the heater is higher than an elevation of a bottom of the enclosure.
12 . The single crystal growth apparatus of claim 11 , wherein the enclosure includes a second region of the apparatus, wherein the first region of the apparatus is between the die opening and the second region of the apparatus.
13 . The single crystal growth apparatus of claim 12 , wherein:
the first region is configured to exhibit a first thermal gradient;
the second region is configured to exhibit a second thermal gradient; and
the first thermal gradient is greater than the second thermal gradient.
14 . The single crystal growth apparatus of claim 11 , further comprising a heat shield disposed adjacent to the die opening.
15 . The single crystal growth apparatus of claim 14 , wherein the heat shield is a horizontal heat shield.
16 . The single crystal growth apparatus of claim 14 , further comprising a vertically disposed insulation shield.
17 . The single crystal growth apparatus of claim 16 , wherein the insulation shield is disposed outside of the heat shield.
18 . The single crystal growth apparatus of claim 11 , wherein the heater is configured to apply heat to a second region of the apparatus, wherein the second region of the apparatus is above the first region of the apparatus.
19 . A single crystal growth apparatus, comprising:
a crucible;
a first heater configured to heat the crucible;
a heat shield disposed above the crucible; and
a second heater configured to heat a region above the heat shield,
wherein the apparatus does not include a third heater between a top of the crucible and the heat shield.
20 . The single crystal growth apparatus of claim 19 , further comprising an enclosure disposed above the crucible, the enclosure including the region.
21 . The single crystal growth apparatus of claim 19 , further comprising an insulation shield, wherein the heat shield is disposed between the insulation shield and the enclosure.