Growth of Planar, Non-Polar, A-Plane GaN by Hydride Vapor Phase Epitaxy

Brief Description

A novel method for growing high-quality thick films of a-plane GaN suitable for use as substrates in homoepitaxial device layer regrowth.

Background

Gallium nitride (GaN) and its ternary and quaternary compounds incorporating aluminum and indium (AlGaN, InGaN, AlInGaN) have proven useful in fabricating visible and ultraviolet optoelectronic devices and high-power electronic devices. GaN and its alloys are most stable in the hexagonal w'rtzite crystal structure. However, the positions of the gallium and nitrogen atoms in this structure leads to polarization of the GaN crystals along the c-axis. Virtually all GaN-based devices are grown parallel to the polar c-axis, due to the relative ease of growing planar Ga-face planes. In addition, strain at the interfaces between adjacent dissimilar layers causes piezoelectric polarization and subsequent charge separation. These polarization effects decrease the likelihood of electron and hole interaction, which is essential for the operation of light-emitting devices. As a result, eliminating these polarization effects inherent to c-axis oriented devices could greatly enhance the efficiency of GaN light-emitting devices.

Description

Scientists at the University of California have developed a novel method for growing high-quality thick films of a-plane GaN suitable for use as substrates in homoepitaxial device layer regrowth. This invention can be used in conjunction with a method for growing reduced-dislocation density non-polar GaN by hydride vapor phase epitaxy (HVPE) (UC Case 2003-224).

Advantages

• Allows for the production of thick a-plane GaN films for use as substrates for polarization-free device growth;

• Produces films of superior quality that are suitable for subsequent device regrowth by a variety of growth techniques.

Applications

• Fabrication of GaN by HVPE

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Patent Status