Fabricating Scalable, High Angle Inclination Semipolar Substrates
Tech ID: 31856 / UC Case 2019-408-0
Devices with a semipolar orientation can avoid the commonly-observed efficiency reduction (“green gap”) that occurs in high-wavelength GaN-based LEDs — which are often oriented along the c-plane. However, substrates that achieve semipolar orientation are not scalable in size and they are prohibitively expensive.
Researchers at the University of California, Santa Barbara have fabricated devices based on a semipolar III-nitride crystal such that successively grown layers of the crystal have a semipolar plane that is perpendicular to the growth direction and includes an exposed semipolar surface. This method allows the fabrication of bulk semipolar substrates at a larger scale and surface area than currently available alternatives. These boules are inclined at 61 degrees with respect to the c-plane, (10-11), which is a highly stable and naturally occurring facet. It is possible to grow thick (10-11) layers by HVPE without structural defects or growth disruption. These thick layers afford larger surface area slicing of highly inclined semipolar orientations, which leads to smaller and more manageable slicing angles.
- Large-scale miscut and semipolar substrates
- Reduced substrate cost
- No growth disruption
- No structural defects
- Smaller slicing angles