Optical properties of coherent InAs/InGaAs quantum dash-in-a-well for strong 2 μm emission enabled by ripening process

Highlights: • Strong 2 μm wavelength emission from defect-free InAs quantum dash-a-well structure. • Intentional ripening process increases InAs nanostructure size and PL intensity. • Optimized InAs quantum dash reveals a small FWHM of 67 meV at 300 K. • Two thermal activation energies from T-dependent PL are related to nanostructure potential barrier. -- Abstract: We report molecular beam epitaxy of InAs quantum dash-in-a-well (DWELL) on InP for 2 μm wavelength emission using intentional ripening. By inserting the quantum dashes into a 10 nm InGaAs quantum well and employing 60 s of ripening, a ground state emission wavelength of 2 μm with an improved photoluminescence (PL) intensity and small linewidth of 67 meV was achieved. Morphological transformation towards taller and shorter nanostructures was observed for the optimized InAs/InGaAs DWELLs. Buried quantum dashes imaged by transmission electron microscopy were 26.7 nm wide in the [110] direction and 4.5 nm tall without misfit dislocations. Temperature-dependent PL measurement revealed no evidence of charge carrier trapping at low temperatures and yielded low thermal activation energies of 19 meV and 161 meV. InAs DWELL with enhanced optical properties enabled by ripening is promising for next-generation short-wavelength infrared lasers on InP.