The research of the group concentrates on the realization of novel optoelectronic materials and devices based on the III/V compounds (AlInGaAs)/GaAs and (AlInGaAs)/InP by molecular beam epitaxy and different fabrication techniques.
One main focus is on the development of materials and devices for high performance semiconductor lasers for optical communication, gas sensing and high power applications. We fabricate and investigate lasers utilizing both interband as well as intersubband transitions. The emission range of interest currently spans from 800 nm to 16 µm.
The second field of activity is the realization of semiconductor quantum dot microcavities for cavity quantum electrodynamic studies. The microresonators are based on dielectric Bragg mirrors or photonic crystals with Q factors exceeding 150.000. These high-Q microcavities are ideal candidates for the investigation of light-matter-interaction in solids. Additionally we are fabricating electrically driven high-Q micropillars for single photon emission.
Moreover, specific epitaxial layers for basic research and nanoelectronic investigation are developed. This includes for the growth of high mobility two dimensional electron gases. Additionally we perform fundamental research on random or site-controlled self-assembled quantum dots for e.g. single dot spectroscopy.
The fabrication of devices is performed with the help of focused ion beam machines and in collaboration with the Nanotechnology Services group who is in charge of the electron beam lithography and etching systems.
Our actual research concentrates on:
- Fundamental research on self-assembled quantum dots (influence of different growth conditions on the morphological and optical properties of quantum dots
- Site-controled growth of quantum dot positions on pre-patterned substrates
- Tailoring of morphological and optical properties of quantum dots
- Realization of high-Q semiconductor quantum dot microresonators for experiments in the field of cavity quantum electrodynamics
- Realization of electrically driven high-Q micropillars for single photon sources
- Vertical cavity surface emitting lasers (VCSEL) and edge emitting quantum dot lasers on GaAs for the 1 - 1.3 µm range
- High power quantum dot lasers for uncooled high power pump modules with cw output powers larger than 8 W
- 1.55 µm – 2 µm quantum dash lasers on InP for optical communication or gas sensing
- GaAs based multi- and single-mode quantum cascade lasers (9 - 14 µm)
- InP based quantum cascade lasers at 5 – 16 µm for gas sensing
- Novel devices based on quantum cascade lasers: photonic crystal microlasers and tapered lasers
- Growth of high mobility electron gasesInGa(Al)As, InGaAsP and AlGaSb heterostructures for 1.5 µm wavelength devices
- High quality InGaAs/InGaAlAs and InGaAs/InP quantum wells
- High quality GaSb quantum wells with narrow luminescence linewidths and optically pumped vertical cavity surface emitting lasersGaSb lasers for the near IR spectral range for highly efficient sensor systems