Carrier Recombination Properties of Low-Threshold 1.3 μm Quantum Dot Lasers on Silicon

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
.