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Pendeoepitaxial gallium nitride semiconductor layers on silcon carbide substrates
| Details |
Inventors: Linthicum, Kevin J.; Gehrke, Thomas; Thomson, Darren B.; Carlson, Eric P.; Rajagopal, Pradeep; Davis, Robert F.;
Assignee: North Carolina State University (Raleigh, NC)
Primary Examiner: Munson; Gene M.
Assistant Examiner:
Attorney, Agent or Firm: Myers Bigel Sibley & Sajovec
An underlying gallium nitride layer on a silicon carbide substrate is masked with a mask that includes an array of openings therein, and the underlying gallium nitride layer is etched through the array of openings to define posts in the underlying gallium nitride layer and trenches therebetween. The posts each include a sidewall and a top having the mask thereon. The sidewalls of the posts are laterally grown into the trenches to thereby form a gallium nitride semiconductor layer. During this lateral growth, the mask prevents nucleation and vertical growth from the tops of the posts. Accordingly, growth proceeds laterally into the trenches, suspended from the sidewalls of the posts. The sidewalls of the posts may be laterally grown into the trenches until the laterally grown sidewalls coalesce in the trenches to thereby form a gallium nitride semiconductor layer. The lateral growth from the sidewalls of the posts may be continued so that the gallium nitride layer grows vertically through the openings in the mask and laterally overgrows onto the mask on the tops of the posts, to thereby form a gallium nitride semiconductor layer. The lateral overgrowth can be continued until the grown sidewalls coalesce on the mask to thereby form a continuous gallium nitride semiconductor layer. Microelectronic devices may be formed in the continuous gallium nitride semiconductor layer. |
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DETAILED DESCRIPTION It is therefore an object of the present invention to provide improved methods of fabricating gallium nitride semiconductor layers, and improved gallium nitride layers so fabricated.
It is another object of the invention to provide methods of fabricating gallium nitride semiconductor layers that can have low defect densities, and gallium nitride semiconductor layers so fabricated.
These and other objects are provided, according to the present invention, by masking an underlying gallium nitride layer on a silicon carbide substrate with a mask that includes an array of openings therein and etching the underlying gallium nitride layer through the array of openings to define a plurality of posts in the underlying gallium nitride layer and a plurality of trenches therebetween.
The posts each include a sidewall and a top having the mask thereon.
The sidewalls of the posts are laterally grown into the trenches to thereby form a gallium nitride semiconductor layer.
During this lateral growth, the mask prevents nucleation and vertical growth from the tops of the posts.
Accordingly, growth proceeds laterally into the trenches, suspended from the sidewalls of the posts.
This form of growth is referred to herein as pendeoepitaxy from the Latin "to hang" or "to be suspended".
Microelectronic devices may be formed in the gallium nitride semiconductor layer.
According to another aspect of the invention, the sidewalls of the posts are laterally grown into the trenches until the laterally grown sidewalls coalesce in the trenches to thereby form a gallium nitride semiconductor layer.
The lateral growth from the sidewalls of the posts may be continued so that the gallium nitride layer grows vertically through the openings in the mask and laterally overgrows onto the mask on the tops of the posts, to thereby form a gallium nitride semiconductor layer.
The lateral overgrowth can be continued until the grown sidewalls coalesce on the mask to thereby form a continuous gallium nitride semiconductor layer
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MEMS 
