Recombination processes in intrinsic and p-doped low-threshold 1.3 µm InAs-based quantum dot lasers on silicon

Data for the paper with the following abstract.

On-chip lasers are a key component for the realization of silicon photonics. The performance of silicon-based quantum dot (QD) devices is approaching equivalent QDs on native substrates. To drive forward design optimization we investigated the temperature and pressure dependence of intrinsic and modulation p-doped 1.3 μm InAs dot-in-well (DWELL) laser diodes on on-axis silicon substrates for comparison with devices on GaAs substrates. The silicon-based devices demonstrated low room temperature (RT) threshold current densities (J_th) of 192 Acm^-2 (538 Acm^-2) intrinsic (p-doped). Intrinsic devices exhibited temperature stable operation from 170-200 K. Above this, J_th increased more rapidly due to increased non-radiative recombination. P-doping increased the temperature at which J_th(T) started to increase to 300 K with a temperature insensitive region close to RT, but with a higher J_th. A strong correlation was found between the temperature dependence of gain spectrum broadening and the radiative component of threshold J_rad(T). At low temperature this is consistent with strong inhomogeneous broadening of the carrier distribution, which is more pronounced in the p-doped devices. At higher temperatures J_th increases due to homogeneous thermal broadening coupled with non-radiative recombination. Hydrostatic pressure investigations indicate that while defect-related recombination dominates, radiative and Auger recombination also contribute to J_th.