High efficiency light emitting diodes from bipolar gallium nitride
First Claim
1. A method of forming an epitaxial layer of p-type gallium nitride suitable for producing p-n junctions and junction diodes, the method comprising:
- directing a molecular beam of nitrogen from an electron cyclotron resonance plasma containing nitrogen atoms onto the growth surface of a single crystal of silicon carbide that provides an acceptable lattice match for gallium nitride;
whiledirecting a molecular beam of gallium in the substantial absence of any other compounds onto the same silicon carbide growth surface;
whilemaintaining the surface at a temperature of less than about 650°
C. but that is otherwise high enough to provide sufficient surface mobility for gallium atoms and nitrogen atoms to form a single crystal epitaxial layer of gallium nitride on the silicon carbide;
whiledirecting an acceptor species onto the surface until a desired epitaxial layer is formed; and
irradiating the epitaxial layer with an electron beam at an energy that is sufficient to activate the acceptor ions in the epitaxial layer, but that is less than the energy that would cause atomic displacement in the epitaxial layer thereby producing the epitaxial layer of p-type gallium nitride.
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Abstract
The invention is a method of growing intrinsic, substantially undoped single crystal gallium nitride with a donor concentration of 7×1017 cm-3 or less. The method comprises introducing a source of nitrogen into a reaction chamber containing a growth surface while introducing a source of gallium into the same reaction chamber and while directing nitrogen atoms and gallium atoms to a growth surface upon which gallium nitride will grow. The method further comprises concurrently maintaining the growth surface at a temperature high enough to provide sufficient surface mobility to the gallium and nitrogen atoms that strike the growth surface to reach and move into proper lattice sites, thereby establishing good crystallinity, to establish an effective sticking coefficient, and to thereby grow an epitaxial layer of gallium nitride on the growth surface, but low enough for the partial pressure of nitrogen species in the reaction chamber to approach the equilibrium vapor pressure of those nitrogen species over gallium nitride under the other ambient conditions of the chamber to thereby minimize the loss of nitrogen from the gallium nitride and the nitrogen vacancies in the resulting epitaxial layer.
763 Citations
15 Claims
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1. A method of forming an epitaxial layer of p-type gallium nitride suitable for producing p-n junctions and junction diodes, the method comprising:
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directing a molecular beam of nitrogen from an electron cyclotron resonance plasma containing nitrogen atoms onto the growth surface of a single crystal of silicon carbide that provides an acceptable lattice match for gallium nitride;
whiledirecting a molecular beam of gallium in the substantial absence of any other compounds onto the same silicon carbide growth surface;
whilemaintaining the surface at a temperature of less than about 650°
C. but that is otherwise high enough to provide sufficient surface mobility for gallium atoms and nitrogen atoms to form a single crystal epitaxial layer of gallium nitride on the silicon carbide;
whiledirecting an acceptor species onto the surface until a desired epitaxial layer is formed; and irradiating the epitaxial layer with an electron beam at an energy that is sufficient to activate the acceptor ions in the epitaxial layer, but that is less than the energy that would cause atomic displacement in the epitaxial layer thereby producing the epitaxial layer of p-type gallium nitride. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification