Recombination mechanisms in 1.3-μm InAs quantum-dot lasers

We measure, in real units, the radiative and total current density in high performance 1.3-μm InAs quantum-dot-laser structures. Despite very low threshold current densities, significant nonradiative recombination (∼80% of the total recombination) occurs at 300 K with an increasing fraction at higher current density and higher temperature. Two nonradiative processes are identified; the first increases approximately linearly with the radiative recombination while the second increases at a faster rate and is associated with the loss of carriers to either excited dot states or the wetting layer