Method and system for carbon doping control in gallium nitride based devices
View Patent ↗A method of growing an n-type III-nitride-based epitaxial layer includes providing a substrate in an epitaxial growth reactor, forming a masking material coupled to a portion of a surface of the substrate, and flowing a first gas into the epitaxial growth reactor. The first gas includes a group III element and carbon. The method further comprises flowing a second gas into the epitaxial growth reactor. The second gas includes a group V element, and a molar ratio of the group V element to the group III element is at least 5,000. The method also includes growing the n-type III-nitride-based epitaxial layer.
1. A method of growing an n-type III-nitride-based epitaxial layer for a drift layer of a diode, the method comprising:
providing a substrate in an epitaxial growth reactor;
flowing a first gas into the epitaxial growth reactor, wherein the first gas includes a group III element and carbon; and
flowing a second gas into the epitaxial growth reactor, wherein:
the second gas includes a group V element; and
a molar ratio of the group V element to the group III element is at least 5,000; and
growing the n-type III-nitride-based epitaxial layer to form the drift layer of the diode.
2. The method of claim 1 wherein the first gas comprises at least one of tri-methyl gallium or tri-ethyl gallium.
3. The method of claim 1 wherein the second gas comprises ammonia.
4. The method of claim 1 wherein growing the n-type III-nitride-based epitaxial layer comprises a metal-organic chemical vapor deposition process.
5. The method of claim 1 wherein the n-type III-nitride-based epitaxial layer has a carbon concentration less than 1×10 16 cm −3 .
6. The method of claim 1 wherein a growth rate of the n-type III-nitride-based epitaxial layer is between 1 μm/hr and 2 μm/hr.
7. The method of claim 1 wherein a thickness of the drift layer is greater than 1 μm.
8. A method of manufacturing a diode, the method comprising:
providing an n-type GaN-based substrate having a first surface and a first electrical contact opposing the first surface;
forming an epitaxial n-type drift layer above the first surface, the epitaxial n-type drift layer having a bottom surface and a top surface, wherein:
the bottom surface is closer to the first surface than the top surface;
the epitaxial n-type drift layer is configured to conduct current;
gases used in forming the epitaxial n-type drift layer include a group V element and a group III element; and
a molar ratio of the group V element to the group III element is at least 5,000; and
forming a second electrical contact above the top surface of the epitaxial n-type drift layer.
9. The method of claim 8 wherein the gas including the group V element comprises at least one of ammonia or cracked ammonia.
10. The method of claim 8 wherein the gas including the group III element comprises at least one of tri-methyl gallium, tri-ethyl gallium, cracked tri-methyl gallium, or cracked tri-ethyl gallium.
11. The method of claim 8 wherein the epitaxial n-type drift layer has a carbon concentration less than 1×10 16 cm −3 .
12. The method of claim 8 wherein a growth rate of the n-type drift layer is between 1 μm/hr and 2 μm/hr.
13. The method of claim 8 wherein the n-type GaN-based substrate comprises an n-type GaN substrate.
14. The method of claim 8 wherein the a molar ratio of the group V element to the group III element is at least 10,000.
15. The method of claim 8 wherein a thickness of the epitaxial n-type drift layer is greater than 1 μm.