Growth of High Quality AlGaN Using In-Situ Deposited SiN 91 MOVPE Growth of High Quality AlGaN Using In-Situ Deposited SiN Nano-Masks

AlGaN layers grown directly on sapphire typically experience fairly strong biaxial compressive strain [1] which leads to a large number of threading dislocations (TDs) — mainly misfit TDs. These mainly occur in the form of edge/mixed type TDs. They cause very broad asymmetric high resolution X-ray diffraction (HRXRD) reflections, e.g. (102)reflexes [2]. On the other hand, screw/mixed type dislocations are mainly responsible for the broadening of the symmetric (002) HRXRD peaks. They do not hamper the device performance as strongly as edge type TDs [3]. Therefore, our main interest in this work is to grow AlGaN epilayers with as narrow as possible asymmetric XRD reflections corresponding to a low density of edge type TDs.