Magnetotunnelling and photoluminescence spectroscopy of self-assembled InAs quantum dots

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 parallel to I; as well as the spin splitting in the QD at B perpendicular to 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 Angstrom. 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 Gamma-point bandgap in bulk GaAs.