Intensive research in the field of self-assembled quantum dots (QDs) has resulted in rapid improvement in the understanding of the principal properties of QDs for developing new quantum devices such as quantum dot infrared photodetectors (QDIP). QDs provide two main advantages for this application: 1) the ability to absorb the normally incident infrared photoexitation, and 2) long (up to ns) photoexcited carrier lifetimes. Normal incidence photoexcitation is desirable for the fabrication of a two-dimensional focal plane array for passive location imaging applications. The long lifetimes ensure higher responsitivity of the detector allowing increased temperature operation. Due to discrete energy levels QDs could be used for tunable narrow-band detection or "fingerprint" of various objects observed from the space. In addition, for QDIP operation at space conditions it is important to investigate also influence of high energy particles irradiation on optical properties of QDs systems.
Small size (~10 nm at the base) InAs/GaAs QDs were investigated using Optically Detected Magnetic Resonance (ODMR) and time-resolved photoluminescence (TRPL) techniques. The ODMR spectra were detected via modulation of the total intensity of the QDs emission induced by 95 GHz microwave excitation and exciton fine structure was studied. Very long life times (up to 10 ns) of photoexcited carriers were observed in this system at low temperatures and excitation intensities promising higher responsitivity of such QDs for QDIP development.
The effects of proton and alpha particles irradiation on carrier dynamics were investigated on different InGaAs/GaAs and GaAs/AlGaAs QD and QW systems. The obtained results demonstrated that carrier lifetimes in the QDs are much less affected by proton irradiation than that in QWs. A strong influence of irradiation on the PL intensity was observed in multiple QW after high-energy particles irradiation.

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