Measurement of the anisotropy of the hole dispersion curves in an AlAs/GaAs/AlAs quantum well grown on a (311)A orientated substrate

Continuous magnetic fields applied parallel to layer interfaces are used to examine the in-plane energy dispersion and anisotropy of the quantum well states of double barrier AlAs/GaAs resonant tunnelling diodes. The devices are grown on substrates with different orientations using molecular beam epitaxy. Measurements on a device grown on a (311)A substrate reveal the pronounced biaxial symmetry of the confined hole states in a quantum well of this orientation, including a marked saddle-shaped structure for one of the subbands. The spectra are compared with those of similar devices grown on a (100) surface.