Electronic properties of GaAsBi(001) alloys at low Bi content

We present an in-depth investigation of structural and electronic properties of GaAsBi epilayers. High (001)crystalline order is achieved using careful molecular beam epitaxy and surface preparation procedures. Highsurface order allows us to use x-ray, ultraviolet, and angle-resolved photoemission spectroscopy at variablephoton energies and to disentangle electronic effects of an atomically thin Bi-rich surface layer with (2 × 3)symmetry from those of Bi atoms incorporated in the GaAs bulk matrix. The influence of bulk-integrated Biconcentrations on the GaAs band structure becomes visible in angle-resolved photoemission after removingBi-rich surface layers by a brief and mild ion bombardment and subsequent annealing treatment. Experimentalobservations are supported by density functional theory simulations of the valence band structure of bulk andsurface-reconstructed GaAs with and without Bi. Bi-induced energy shifts in the dispersion of GaAs heavy andlight hole bulk bands are evident both in experiment and theory, which are relevant for modulations in the opticalband gap and thus optoelectronic applications.