Abstract
Ultrafast differential transmission spectroscopy is used to explore temperature-dependent carrier dynamics in an InAs/InGaAs quantum dots-in-a-well heterostructure. Electron-hole pairs are optically injected into the three dimensional GaAs barriers, after which we monitor carrier relaxation into the two dimensional InGaAs quantum wells and the zero dimensional InAs quantum dots by tuning the probe photon energy. We find that carrier capture and relaxation are dominated by Auger carrier-carrier scattering at low temperatures, with thermal emission playing an increasing role with temperature. Our experiments provide essential insight into carrier relaxation across multiple spatial dimensions.
Highlights
Low dimensional semiconductor nanostructures have attracted much attention due to the unique size-dependent scaling of their physical properties, providing researchers an opportunity to tune these parameters in a manner not afforded by naturally occurring bulk materials
It is comprised of 15 layers, each consisting of 2.4 ML of InAs quantum dots (QDs) grown on a 1 nm InGaAs quantum wells (QWs), capped by a 6 nm InGaAs QW, and placed in a GaAs matrix; further growth details are described in references [3] and [19]
We find that electron-electron scattering governs electron capture into the QDs from the QWs, with electron relaxation from the QD n=2 to the QD n=1 state governed by electron-hole scattering at low temperatures
Summary
Low dimensional semiconductor nanostructures have attracted much attention due to the unique size-dependent scaling of their physical properties, providing researchers an opportunity to tune these parameters in a manner not afforded by naturally occurring bulk materials. Electron-hole pairs are optically injected into the three dimensional GaAs barriers, after which we monitor carrier relaxation into the two dimensional InGaAs quantum wells and the zero dimensional InAs quantum dots by tuning the probe photon energy. We perform temperature and wavelength dependent differential transmission (DT) spectroscopy to examine carrier relaxation in a DWELL heterostructure.
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