Magneto-tunnelling spectroscopy of nitrogen clusters in Ga(AsN) alloys

Magneto-transport studies in an n-i-n doped GaAs/AlAs/Ga(AsN) heterostructure are described. This system acts as a resonant-tunnelling diode in which electrons can tunnel through the N-induced states in the Ga(AsN) layer. Magnetotunnelling spectroscopy with magnetic fields parallel and perpendicular to the current direction is used to probe the nature, band-like or impurity-like, of the N states. The data indicate that the electron wavefunction of the N states is strongly localised and extends over distances smaller than 1.8 nm.