Magnetotunnelling and Photoluminescence Spectroscopy of Self-Assembled InAs Quantum Dots

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Abstract
Self-assembled InAs quantum dots (QDs) in AlAs and GaAs matrices are investigated by tunnelling and optical spectroscopy. Tunnelling through an individual QD in the AlAs barrier of a n-i-n single-barrier device is used to probe the properties of both the emitter two-dimensional electron gas (2DEG) and the QD. The Landau fan of the 2DEG is mapped at magnetic field parallel to the tunnelling current, B\VertI, as well as the spin splitting in the QD at B⊥I. An electron g-factor in the QD is determined as ∣g∣=1.2±0.5. In the photoluminescence spectrum of InAs QDs in B up to 23 T, a strong anisotropy in the diamagnetic shift is found. The spatial extent of the carrier wave function in the dot is estimated as 60 Å. Under hydrostatic pressure up to 8 kbar, the pressure coefficient for the dot emission line is (9.1±0.2) meV/kbar, about 20% smaller than for the Γ-point bandgap in bulk GaAs.