Interplay Effect of Excitation and Temperature on Carrier Transfer between Vertically Aligned InAs/GaAs Quantum Dot Pairs

Abstract

Carrier transfer in vertically-coupled InAs/GaAs quantum dot (QD) pairs is investigated. Photoluminescence (PL) and PL excitation spectra measured at low temperature indicate that the PL peak intensity ratio between the emission from the two sets of QDs-i.e., the relative population of carriers between the two layers of QDs-changes with increasing excitation intensity. Temperature-dependent PL reveals unexpected non-monotonic variations in the peak wavelength and linewidth of the seed layer of QDs with temperature. The PL intensity ratio exhibits a "W" behavior with respect to the temperature due to the interplay between temperature and excitation intensity on the inter-layer carrier transfer.

Carrier Injection to In0.4Ga0.6As/GaAs Surface Quantum Dots in Coupled Hybrid Nanostructures

“…In comparison, the decay curves for the SQDs were determined to be multi-exponential in nature, and the bi-exponential function, I(t) = A 1 exp[−(t−t 0 )/τ 1 ] + A 2 exp[−(t−t 0 )/τ 2 ], was used to fit them. This was due to either the indirect transition of the SQDs or the fast carrier transfer from the SQDs to surface states [42,43]. In this case, we associate the index, 1, with the slower lifetime of carrier recombination, τ 1 , and the index, 2, with the faster carrier transfer time, τ 2 , from the SQDs to the surface states.…”