When the first working laser was demonstrated in 1960 critics described it as a solution looking for a problem. Much has happen since then and the laser is now an important part of our lives, enabling eye surgery, projector displays, broadband internet connections, bar-code readers, gas spectroscopy, blu-ray DVD players, etc.
There are many different types of lasers, where one example is the microcavity laser, sometimes also referred to as the vertical-cavity surface-emitting laser (VCSEL). It is a semiconductor-based laser that is today mainly used in short-reach data communication links and computer mice. Due to its low power consumption, easy integration into 2D arrays, and low-cost it has also become very attractive for many bio-medical applications.
However, these applications typically require emission wavelengths in the blue-UV regime, which are not available today. To reach these emission wavelengths the laser must be made in a different material system that can provide optical amplification in the desired spectral range. One such material system is nitrogen combined with group III materials, i.e. GaN, AlGaN, AlInN and InGaN. However, these III-nitride materials have so far shown very poor electrical performance making it difficult realize an electrically driven laser, which is a necessity for real-world applications.
So far, only two research groups in the world have demonstrated electrically driven blue VCSELs, and there is still a lot to do when it comes to understanding and improving the devices. The two main challenges are:
- to obtain high electrical conductivity in the III-nitride material system for low device resistance and highly efficient current injection
- achieving mirrors that are lattice matched to the substrate (often GaN) and have high enough reflectivity to reach lasing
In this project we will address both these challenges.
Job description
As a PhD student in our group you will be working on design and modeling and also participate in fabrication and characterization of these lasers. We have a long experience on designing VCSELs using in-house-developed models mainly for emission wavelengths longer than 600 nm, and you will work on expanding these models to be able to include microcavity lasers emitting in the blue regime. You will be trained in device fabrication using state-of-the-art equipment in the MC2 clean room as well as characterization of fabricated devices in our measurement laboratory. Much of the work will be conducted in collaboration with external partners.
The majority of your working time is devoted to your own research studies. A PhD student is also expected to develop own ideas and communicate scientific results orally as well as in written form. In addition, the position will normally include 20% departmental work, mostly teaching duties. The employment is limited to a maximum of five years.
PhD student position in Blue Microcavity Lasers
