The MikroLED Lab (MLL) was funded by the European Regional Development Fund (ERDF) in the More Developed Region programme category.
The Institute of Semiconductor Technology at TU Braunschweig is one of the world's leading university research institutes for the research and development of micro-photonic components based on gallium nitride. One focus is on MicroLEDs. MicroLEDs are very small LEDs with dimensions in the micrometer range. The highly miniaturized light emitters are characterized by some very special properties. For example, the light from a MicroLED has a large coherence length, as all photons are emitted from practically the same point in space. The MicroLED serves as an almost ideal point light source. This results in interference phenomena that can be used, for example, for holographic microscopy.
In addition, MicroLEDs can be arranged in arrays. If individual MicroLEDs are switched on and off, a point of light can be moved over an object without any mechanical components, as is usually the case with typical laser scanners. A miniaturized image of the MicroLED array can be used to achieve a spatial resolution of less than 50 nm with an uncertainty of less than 5 nm. The current research goal is to clarify through basic experiments whether this type of super-resolution illumination can also be used for imaging with super resolution, i.e. a local resolution beyond the diffraction limit.
While so far the different MicroLEDs in a module only emit incoherent light, it will become particularly important in the future to couple the MicroLEDs or MicroLasers coherently in the network and to adjust and control the relative phase to each other. This will then allow completely new applications, such as the generation of photons with high angular momentum (twisted light) or the control of the direction of light emission. For this purpose, however, arrays of phase-coupled MicroLasers that emit light vertically must be developed. This requires research into vertically emitting laser diodes (VCSELs) and phase-coupled laser arrays based on them.
In the MLL project, the EFRE funds were used to upgrade the infrastructure in the laboratories of the Institute of Semiconductor Technology. On the one hand, this involves the process technology for the production of GaN components, e.g. a sputtering system for diffusion barriers, contact and adhesive layers. On the other hand, the nanoanalytical possibilities were significantly improved by providing a spectroscopic ellipsometer and extensions of the cavity ringdown measurement setup and the Raman spectroscopy.