Growth of AlInN/GaN distributed Bragg reflectors with improved interface quality

We report on lattice-matched AlInN/GaN distributed Bragg reflectors (DBRs) with improved overgrowth of the AlInN layers. Typically, AlInN layers are exposed to high temperatures when changing to GaN growth conditions. Uncapped AlInN surfaces suffer from In desorption leading to formation of 2 nm thick AlN interface layers with micro-cracks at the AlInN surface. Capping the AlInN with 5 nm GaN at the same temperature and subsequent overgrowth with GaN at high temperatures resolves the In-desorption problem and DBRs with improved interface quality and smooth surfaces are achieved. Optical properties of high-reflectivity DBR structures such as maximum reflectivity and bandwidth are virtually unaffected whether or not unintentionally-grown AlN interlayers are present.