Vertical transport and tunnelling through squeezable quantum dots

Resonant tunnelling through zero-dimensional states in a laterally confined double-barrier quantum well heterostructure has been investigated. The lateral confinement is provided by a Schottky gate which allows continuous squeezing of the current channel to diameters smaller than 100 nm. The conductance data on submicron dots exhibit well-resolved peaks, the position of which depends on both channel diameter and applied magneticfield. The measured displacement of the conductance peaks with decreasing channel diameter provides direct evidence of quantum confinement in the dot. In addition magnetotunneling measurements lend experimental support to the observation of zero-dimensional states with positive and negative azimuthal quantum number ℓ. © 1993.