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Terahertz activated luminescence of trapped carriers in InGaAs/GaAs quantum dots

Bhattacharyya, J.; Wagner, M.; Helm, M.; Hopkinson, M.; Wilson, L. R.; Schneider, H.

Optical properties and interdot transfer dynamics of trapped carriers in InGaAs quantum dots (QDs) are investigated. Time resolved photoluminescence (PL) was measured for time-delayed interband and intraband excitations. Terahertz activated luminescence (TAL) from trapped carriers having lifetimes of ~250 ns at 8 K, was observed. Spectral shift of the TAL with respect to the PL showed the trionic nature of the PL in the n-doped QDs. With increasing terahertz excitation intensity, the TAL increased and reached saturation. The activation energy associated with the trapped carrier decay was quite close to the intersublevel transition energy (~20 meV) indicating trapping in the QDs.

Keywords: Quantum dots; Photoluminescence quenching; trapped carriers

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Publ.-Id: 14427