Abstract
We demonstrated onset of deep-ultraviolet (DUV) surface stimulated emission (SE) from c-plane AlGaN multiple-quantum well (MQW) heterostructures grown on a sapphire substrate by optical pumping at room temperature. The onset of SE became observable at a pumping power density of 630 kW/cm(2). Spectral deconvolution revealed superposition of a linearly amplified spontaneous emission peak at lambda similar to 257.0 nm with a full width at half maximum (FWHM) of similar to 12nm and a superlinearly amplified SE peak at lambda similar to 260 nm with a narrow FWHM of less than 2 nm. In particular, the wavelength of similar to 260 nm is the shortest wavelength of surface SE from III-nitride MQW heterostructures to date. Atomic force microscopy and scanning transmission electron microscopy measurements were employed to investigate the material and structural quality of the AlGaN heterostructures, showing smooth surface and sharp layer interfaces. This study offers promising results for AlGaN heterostructures grown on sapphire substrates for the development of DUV vertical cavity surface emitting lasers (VCSELs). (C) 2015 AIP Publishing LLC.