V. N. Jmerik, E. V. Lutsenko and S. V. Ivanov Plasma-assisted molecular beam epitaxy of AlGaN heterostructures for deep-ultraviolet optically pumped lasers physica status solidi (a) 210
Plasma-assisted molecular beam epitaxy of AlxGa1 − xN-based quantum well (QW) structures with high Al content (up to 50% in the QW) grown directly on c-sapphire is described in this Feature Article. Special attention is paid to the growth conditions of (i) AlN nucleation layers with suppressed generation of threading dislocations (TDs), (ii) atomically-smooth 2-μm-thick AlN buffer layers with several 3-nm-thick strained GaN insertions and AlGaN/AlN superlattice to decrease TD's density down to 108–109cm−2, (iii) cladding and waveguide AlGaN layers with atomically-smooth droplet-free morphology and QW region fabricated by a sub-monolayer digital alloying technique. These QW structures demonstrate optically-pumped lasing within the deep-UV (sub-300 nm) wavelength range with threshold power density below 600 kW/cm2 (at 289 nm).
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