Analyse struktureller Eigenschaften von GaN mittels hochauflösender Röntgenbeugung bei variabler Meßtemperatur

The objective of this work is the investigation of the strain and the stress in GaN-based semiconductor layers by high-resolution x-ray diffraction (HRXRD) at variable temperatures. Due to the lack of native substrates GaN-based layers are typically grown on foreign substrates, which results in strained layers with a complex strain configuration. Moreover, heterostructures of group-III nitrides grown along the [0001] direction suffer from strong polarization fields perpendicular to their interfaces, which are undesirable for light-emitting devices whose active regions consist of quantum wells. Therefore, group-III nitride layers have been recently grown on non-polar planes, such as the a-plane. To account for the various questions regarding strain and stress in group-III-nitrides, the spectrum of different GaN layers, which were studied in this thesis, spans from bulk-like free-standing layers over thick c-plane layers to laterally overgrown structures and non-polar a-plane layers.