Our research deals with problems concerning both the characteristics of and production of semiconductors. Our research group is the only one of its kind in Sweden. We have access to molecular beam epitaxy (MBE) with which we can build up different layers of material on a given substrate, atom by atom...

Xinyu Liu's current project is growing and characterizing GaN/AlN multiple quantum wells for intersubband modulators. Due to the large band-offset, ~ 2 eV, in GaN/AlN heterostructures, there is a significant potential to use intersubband transitions (ISBT) in short wavelength devices, such as are light emitters, modulators, detectors and amplifiers, which can operate at wavelengths below 1.6 μm for telecommunication applications. However, due to the large lattice mismatch and the thermal expansion coefficient difference between GaN and AlN, which are ~ 2.5 % along the a-axis and ~30 % at room temperature, the crystallographic homogeneity and strain properties in GaN/AlN MQWs are not fully understood.