We present results on growth and fabrication experiments of AlN/AlGaN superlattices for ultraviolet "UV" optoelectronic devices. Superlattices with extremely short periods have been studied. The AlN ?barrier? layers are 0.5 nm thick, and the AlxGa1-xN ?wells? are 1.25 nm thick, with x ~ 0.08. This combination gives an average AlN mole fraction of 0.63 across one full period. The superlattice periods, AlN mole fractions, and energy gaps are determined using ...
We report post-growth micro-Raman stress mapping of cracks in GaN, AlN, and AlxGa1-xN grown on (111) oriented silicon. Cracks with an average spacing of ~ 100 mum are observed. These cracks are categorized into two types. The first type of crack propagates through the epilayer, and several microns deep into the substrate and is observed in all the samples investigated. The second type cracks epilayer only and is observed only ...
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