Journal of Applied Physics
Using 800 nm, 25-fs pulses from a mode locked Ti:Al2O3 laser, we have measured the ultrafast opticalreflectivity of MBE-grown, single-layer In0.4Ga0.6As/GaAs quantum-dot (QD) samples. The QDs are formed via two-stage Stranski-Krastanov growth: following initial InGaAs deposition at a relatively low temperature, self assembly of the QDs occurs during a subsequent higher temperature anneal. The capture times for free carriers excited in the surrounding GaAs (barrier layer) are as short as 140 fs, indicating capture efficiencies for the InGaAs quantum layer approaching 1. The capture rates are positively correlated with initial InGaAs thickness and annealing temperature. With increasing excitedcarrier density, the capture rate decreases; this slowing of the dynamics is attributed to Pauli state blocking within the InGaAs quantum layer.
Chauhan, K. N.; Riffe, D. Mark; Everett, E. A.; Kim, D. J.; Yang, H.; and Shen, F. K., "Carrier Capture Dynamics of Single InGaAs/GaAs Quantum-Dot Layers" (2013). All Physics Faculty Publications. Paper 2021.