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Using magneto-tunneling spectroscopy, we observe the Zeeman spin splitting of the ground state of a single InAs quantum dot grown within AlAs. We obtain values for the g factor of different quantum dots between +0.52±0.08 and +1.6±0.2, with magnetic field applied in the plane of the dot. This value for the g factor is considerably different from that of bulk InAs (g=−14.8), and we explain this using a simple three band k⋅p calculation. Using the spin split states of the dot as a probe, we observe the complete spin polarization of the emitter accumulation layer.

A single InAs self-assembled quantum dot is incorporated in the barrier of a tunnel diode and used as a spectroscopic probe of an adjacent two-dimensional electron system from the Fermi energy to the subband edge. We obtain quantitative information about the energy dependence of the quasiparticle lifetime. For magnetic field B, applied parallel to the current, we observe peaks in the current-voltage characteristics I(V) corresponding to the formation of Landau levels. Close to filling factor nu=1 we observe directly the exchange enhancement of the Lande g factor.

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