Two key gallium nitride developments lighting up the LED market Our expertise

Silicon-based LED offers a variety of advantages including low cost and compatibility with the existing semiconductor manufacturing infrastructure. GaN-on-silicon can deliver over 70 percent power efficiency, and upward of four to six times power per unit area with scalability to high frequencies.

By developing GaN LEDs on silicon substrates and integrating the two materials, several technical challenges must be addressed. The main challenges are the large lattice mismatch between GaN and silicon, and the large difference in thermal expansion coefficients.

Control of strain and wafer bow is critical for the epitaxial process and this requires very fine control over both absolute wafer temperature and temperature uniformity. Thin-film LEDs fabricated from these materials have efficiencies on par with the best efficiencies of LEDs grown on conventional substrates.

With display technologies gaining more interest, demand to produce self-emitting and individually controlled light sources at the microscale have also picked up. However, the current technology is not suitable for the fabrication of arrays of submicron light sources that can be controlled individually.

This is where GaN-based nano-LEDs are developed as core elements of a novel on-chip super-resolution microscope. Because of its relatively slow GaN surface recombination, GaN micro-LEDs have a high efficiency even at very small dimensions, upon which the surfaces usually play a dominant role in carrier recombination. This contrasts with conventional InGaAlP LEDs where the efficiency substantially decreases for dimensions smaller than 20 µm.

This technology truly opens a broad landscape of applications, targeting the area of super-resolution. A platform of several individually switchable nano LEDs with a nanoscale pitch allows the creation of light patterns with unprecedented spatial resolution. Applications of such chip-based structured illumination systems extend from the emission of controlled light patterns for twisted light to spatially resolved illumination in optogenetics experiments.

Growing a high-quality large-sized GaN crystal is becoming important because of its wide engineering applications in optoelectronics and power devices. As X-ray diffraction (XRD) rocking curve measurements are performed at several points on the wafer, this method is suitable for understanding the one-directional orientation of the local structure.

Currently, X-ray diffraction is a powerful analytical method for characterizing materials and understanding their structural features, particularly in the field of GaN deposition.

XRD analysis provides crucial information about the materials phases including crystalline structure, average crystallite size, micro and macro strain, orientation parameter, texture coefficient, degree of crystallinity and crystal defects. These are very important in the various fields of scientific and material engineering.