28-11-2013 дата публикации
Номер: US20130313567A1
A GaN crystal multi-layer substrate having surfaces with various crystal orientations formed on a sapphire base substrate, such as a substrate whose principal surface is a <11-20> plane which is the a-plane, a <1-100> plane which is the m-plane, or a <11-22> plane having a low threading dislocation density and high crystal quality of a GaN crystal, and a production process therefor. 1. A gallium nitride crystal multi-layer substrate comprising a sapphire base substrate and a gallium nitride crystal layer which is firmed by crystal growth on the substrate , wherein{'sup': 8', '2, 'the gallium nitride crystal layer is formed by lateral crystal growth from the sidewalls of a plurality of grooves formed in the principal surface of the sapphire base substrate in such a manner that the surface thereof is parallel to the principal surface, and the dark-spot density of the gallium nitride crystal is less than 2×10/cm.'}2. The gallium nitride crystal multi-layer substrate according to claim 1 , wherein the dark-spot density of the gallium nitride crystal is not more than 1.4×10/cm.3. The gallium nitride crystal multi-layer substrate according to claim 1 , wherein the gallium nitride crystal layer has a surface with a nonpolar or semipolar orientation.4. The gallium nitride crystal multi-layer substrate according to claim 1 , wherein the sidewalls which are the starting points of lateral crystal growth are each the c-plane of a sapphire single crystal.5. A process for manufacturing a gallium nitride crystal multi-layer substrate claim 1 , comprising the steps of:forming a plurality of grooves, each having sidewalls inclined with respect to the principal surface of a sapphire base substrate, in the sapphire base substrate; andlaterally growing a gallium nitride crystal selectively from the sidewalls of the grooves, whereinthe width (d) of an area for growing a gallium nitride crystal on the sidewalls is set to 10 to 750 nm.6. The process for manufacturing a gallium nitride ...
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