Recombination and Loss Mechanisms in Low-Threshold InAs–GaAs 1.3-μm Quantum-Dot Lasers

We show that even in quantum-dot (QD) lasers with very low threshold current densities (Jth = 40–50 A/cm at 300 K), the temperature sensitivity of the threshold current arises from nonradiative recombination that comprises ∼60% to 70% of Jth at 300 K, whereas the radiative part of Jth is almost temperature insensitive. The influence of the nonradiative recombination mechanism decreases with increasing hydrostatic pressure and increasing band gap, which leads to a decrease of the threshold current. We also studied, for the first time, the band gap dependence of the radiative part of Jth, which in contrast increases strongly with increasing band gap. These results suggest that Auger recombination is an important intrinsic recombination mechanism for 1.3-μm lasers, even in a very low threshold QD device, and that it is responsible for the temperature sensitivity of the threshold current.