CL spectra and corresponding monochromatic CL maps. A schematic of the samples is also shown for structure A (top) and B (bottom).
Edge emission as a function of the wavelength for the sample with homogeneous wells (a), and with strong band-structure compositional fluctuations (b). Data are scaled by the excitation fluence.
Peak position (black dots, left side axis) and FHWM (red circles, right side axis) of the edge emission spectra from the sample with compositional fluctuations as a function of the pump fluence.
FWHM measured at different fluences as a function of the inverse of the ASE intensity. Continuous line is a linear fit of the data.
Measured peak intensity for the sample with (black dots) and without (red circles) compositional fluctuations as a function of the analyzer angle.
(Top) schematic picture of the VSL measurement set-up. (Bottom) VSL traces collected at the peak wavelength at different pump fluences. Data are normalized and continuous lines are the best-fit with Eq. (1) . Green triangles, red dots, and black squares refer to the sample with homogeneous wells. Blue circles were collected from the sample with compositional fluctuations.
Absorption/gain spectra measured at the highest pump fluence for the sample with (black dots) and without (red circles) compositional fluctuations.
Calculated gain spectra of a multiple-quantum-well structure consisting of 1.5-nm-thick Al0.7Ga0.3N wells and 40-nm-thick Al0.9Ga0.1N barriers, for different values of the injected carrier density (ranging from 3 × 1019 cm−3 to 6 × 1019 cm−3 in steps of 0.5 × 1019 cm−3, in order of increasing peak gain). Inset: calculated valence-subband structure of the same sample.
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