Characteristics of high Al‐content AlGaN/AlN quantum wells fabricated by modified migration enhanced epitaxy

High‐quality AlxGa1‐xN/AlN multiple quantum wells (MQWs) with high‐Al content (x > 0.69) were fabricated by modified migration enhanced epitaxy (MEE), characterized by the repetition of simultaneous supply and alternating supply of group III and group V sources. The fabrication of MQWs was confirmed from x‐ray diffraction satellite peaks. With higher growth temperatures, the Al incorporation in the well layer increased. The surface was atomically smooth, and the photoluminescence (PL) spectra showed negligible deep‐level emission, attesting the high quality of the active layers. The ratio of low‐temperature and room‐temperature PL, which approximates the internal quantum efficiency, was as high as ∼36% at an emission wavelength of ∼240 nm. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)