Reduced Dislocation Density of Non-Polar GaN Grown by Hydride Vapor Phase Epitaxy

Brief Description

A novel method for producing low-dislocation density non-polar GaN by hydride vapor phase epitaxy (HVPE).

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. In addition, defect densities in directly grown GaN films are much higher that those found in more traditional III/V semiconductor systems, such as the arsenides and phosphides.

Description

Scientists at the University of California have developed a novel method for producing low-dislocation density non-polar GaN by hydride vapor phase epitaxy (HVPE). This invention complements the method for producing thick planar films of a-plane GaN by HVPE (UC Case 2003-225) by allowing single-step fabrication of reduced defect density material.

Advantages

• Significantly improves film quality by allowing fabrication of enhanced GaN substrate layers for subsequent non-polar device fabrication;

• Greatly improves subsequent device performance.
  

Applications

• Fabrication of low-dislocation density GaN by HVPE.

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Patent Status