Tunneling-barrier controlled excitation transfer in hybrid quantum dot-quantum well nanostructures

Abstract

A systematic spectroscopic study of the carrier transfer between quantum dot (QD) and quantum well (QW) layers is carried out in a hybrid dot-well system based on InAs QDs and InGaAs QWs. We observe a strong dependence of the QD and QW photoluminescence (PL) both on the dot-well barrier thickness and height. For thick (or high) barriers QD and QW systems accumulate independently sufficient photogenerated carrier densities to be seen in PL even at low nonresonant excitation power. For thin (or low) barriers it is impossible to detect the PL signal from QW at low excitation densities due to effective carrier transfer from QW to QDs. Strong state-filling effects of the excited QD states influence the carrier transfer efficiencies. By investigating the carrier dynamics using time-resolved spectroscopy and the state-filling effects in the continuous wave excitation regime the basic characteristics of interlevel, intersublevel, and dot-well relaxation are determined. The mechanisms of the dot-well coupling are discussed.

Acoustically regulated carrier injection into a single optically active quantum dot

“…Thus, further improvements could be achieved by advanced QD architectures providing high mobility transport channels. In addition to hybrid coupled QD-QW structures 29 , these include self-assembled quantum posts 30 for which single photon emission 31 , enhanced acousto-electric transport 8 and remote SAW-driven carrier injection 10 has been recently demonstrated. For short wavelength operation, "inverted" GaAs/AlGaAs QDs with tunable WL thickness 32 could be the system of choice.…”

Effects of the interfacial polarization on tunneling in surface coupled quantum dots

“…The interface between a semiconductor quantum dot (QD) and an extended film is an important part of the functionality of many nanostructured devices, with such diverse applications as photovoltaics [1][2][3] , low threshold lasers 4,5 , single electron memory 6 , and single photon emitters 7,8 . Understanding the physics of this interface is important for the ultimate technological challenges in these applications: increasing energy conversion efficiency of solar cells, controlling speed and volatility in memory devices, and creating reliable on-demand sources of single photons.…”

“…Hot carrier transfer was recently demonstrated for optically excited PbSe QDs coupled to a TiO 2 substrate 3 . In laser applications, the reverse process is utilized to design the transfer of cold carriers from a quantum well to a QD, reducing the energy deposition by hot carriers and leading to higher gain and lower thresholds 4,5 . The large tunability of QDs allows flexibility to construct fast volatile memories as well as non-volatile memories with very long retention times, low electrical damage, and the possibility of charge storage based on holes as opposed to electrons 6 .…”

Power-dependent spin amplification in (In, Ga)As/GaAs quantum well via Pauli blocking by tunnel-coupled quantum dot ensembles

“…One example is quantum well (QW) and quantum dot (QD) tunnel-coupled nanostructures. [1][2][3][4][5][6][7][8][9] In such hybrid systems, QWs serve as reservoirs for carriers/excitons, whereas the three-dimensional (3D) potential surrounding QDs efficiently confines the carrier/exciton motion. This confinement leads to long-lived spin states due to the suppression of spin-orbit interaction-induced relaxation processes.…”