Developing a material platform for energy-efficient III-Nitride RGB nano-LEDs

The project aims at developing a platform for the design and growth of sub-micron sized light-emitting diodes (nano-LEDs) using III-Nitride heterostructures. The platform is based on selective area growth of flat platelets.

The LEDs are aimed at several applications from LED lighting using three coloured LEDs; self-emissive RGB displays for virtual reality; and nano-LEDs for sub-wavelength imaging.

We target the entire visible colour range, with emphasis on red emission, the most challenging colour from a technological point of view. The main challenge lies in the large lattice mismatch between the binary compounds InN and GaN, about 10%.

This will introduce structural defects if the difference between the In content of the layers in the heterostructure is not kept low enough, where red LEDs require the highest In concentration. Commercial blue LEDs have a manageable mismatch between GaN and InGaN, where the In concentration is about 15%.

Red needs about 35% In, potentially deteriorating the material quality.

A second challenge is the lack of large-scale GaN (or InGaN) substrates, and the starting point is a strained GaN layer on a foreign substrate.

Even when using an InGaN intermediate layer, the mismatch with the GaN substrate layer is too high.We have recently created a generic materials technology platform enabling the realization of dislocation-free and fully relaxed, c-oriented, micron-sized platelets of GaN and InGaN that we will explore in this project.