This work presents an investigation of room temperature ultra-fast carrier dynamics in a p-doped dash-in-a-well structure emitting at 1.5 μm using single colour heterodyne pump-probe spectroscopy. This technique enabled simultaneous access to the gain and refractive index dynamics in various operational conditions including both the absorption and gain regime. Comprehensive analysis of the timescales related to carrier relaxation and escape processes in addition to the ’dynamical’ linewidth enhancement factor are presented and compared with results obtained from similar un-doped materials. The direct influence of the p-doping on the carrier dynamics is also discussed.
In this work, the optical properties and emission dynamics of core-shell InGaAs/GaAs nanopillars (NPs) have been in-
vestigated using low-temperature photoluminescence (PL) and time-resolved photoluminescence (TRPL). These novel
structures have recently attracted much interest within the silicon photonics scientific community due to their potential
employment as gain medium for monolithically integrated lasers on silicon substrates. The optimization of the emission
properties of these heterostructures is essential to obtain full compatibility with silicon photonics and requires an accurate
tailoring of the pillar geometry (i.e. size, pitch) and composition. Therefore it is critical to gain deeper insight into the
optical and dynamical properties of different NP designs if optimal device performance is to be achieved. The experimental
characterization, carried out on a number of different NP structures with different geometries and compositions, shows that
the time evolution of the emission peak exhibits a strong excitation-dependent blue-shift which can be attributed to the
band-filling effect. Measured emission decay times were strongly geometry-dependent and varied from nanoseconds to
tens of picoseconds. In addition, a dramatic reduction of the decay time was observed for the highest indium concentration
due to the dominant contribution of the strain-induced non-radiative recombination processes.