VERTICAL TUNNELING BETWEEN 2 QUANTUM DOTS IN A TRANSVERSE MAGNETIC-FIELD

Tunneling between two quantum dots is studied at low temperatures. The quantum dots are formed by the combined sidewall confinement and vert ical confinement in an AlxGa1-xAs-GaAs triple-barrier diode with a con ducting diameter of 180 nm. The fine structure that is observed in the main resonance peaks of the current-voltage characteristics is relate d to lateral quantization effects. Electrons tunnel between zero-dimen sional (OD) states in the two coupled quantum dots. A magnetic field a pplied perpendicular (transverse) to the tunneling direction shifts th e main (2D) resonance peaks to higher bias and causes a substantial br oadening. Within the fine structure we find that the resonance positio ns are virtually magnetic-field independent, whereas the resonance amp litudes show significant variations with increasing magnetic field; a simple model is developed to describe this behavior in terms of the ma gnetic-field dependence of the interdot transition probabilities.