Adlayer control for tunable AlGaN self-assembled superlattices

AlGaN self-assembled superlattices (SASLs) and their customization were investigated via metal modulated epitaxy. Using the dynamics of metal accumulation, surface strain, and surface segregation, coherent SASL structures were demonstrated with high repeatability over 910 nm (63 periods) with no growth interrupts at rates as high as 2.8 μm/h. High customizability was shown with control over period thickness as well as the thickness of the individual layers. Factors effecting the thickness and composition of each layer are discussed and methods of customization are presented. Transmission electron microscopy shows abrupt interfaces between individual layers of the SASL and good coherency throughout the structure and strong wavelength tunable ultraviolet photoluminescence was observed. Such a method of SASL fabrication offers promise for the growth of multi-quantum well structures, distributed Bragg reflectors, strain relaxation buffers, and beyond without the need for growth interrupts, and thus unintentional contaminant incorporation, between layers.