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 (J_th=40--50 A/cm² at 300 K), the temperature sensitivity of the threshold current arises from nonradiative recombination that comprises ∼60% to 70% of J_th at 300 K, whereas the radiative part of J_th 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 J_th, 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.