Ultravioletta och blå mikrokavitetslasrar

Research Project, 2019 – 2024

This project aims at developing the very first electrically injected ultraviolet (UV) microcavity laser, as well as the first electrically injected blue microcavity laser with good enough performance to be useful in real-world applications. Achieving ultraviolet emission has proven to be difficult, in particular for microcavity lasers due to high optical losses and defect densities. Our group, with a world-leading position in microcavity laser research, has identified new possibilities to combat these challenges in both ultraviolet and blue-emitting devices. The two recent breakthroughs in our group are:The discovery of an overlooked loss mechanism and schemes to circumvent it.A new method to etch inert AlGaN, resulting in the world’s first thin-film UV-B LED. This method enables the substrate to be lifted-off and be replaced by a high-reflectivity mirror. Recycling the substrate allows for the use of expensive lattice-matched substrates, which drastically improves material quality. These two new approaches will be combined with a focused effort to circumvent the well-known problem of low electrical conductivity of p-doped materials. We will strengthen our capabilities by developing tunnel junctions, allowing highly conductive n-doped material to be used throughout virtually the entire laser. This will drastically reduce losses, which cause severe degradation within minutes in blue microcavity lasers, and might be the only practical solution to electrically driven UV-lasers.