OBSERVATION OF WANNIER-STARK LADDERS IN GAINAS-ALGAINAS SEMICONDUCTOR SUPERLATTICES

We studied some GaInAs-AlGaInAs semiconductor superlattices grown by molecular beam epitaxy and lattice matched to InP substrates. We performed photocurrent and photocurrent-voltage under monochromatic illumination at different energies measurements. The spectra recorded at 80 K exhibit three Wannier-Stark ladders. We identified them as corresponding to the 1s ground state of respectively the heavy- and light-hole exciton and to the 2s excited state of the heavy-hole exciton. Using the 1s-2s splitting energy, the binding energy of the heavy-hole exciton ground state can therefore be accurately evaluated.