beta-Ga2O3 nanostructures including nanowires, nanoribbons and nanosheets were synthesized via thermal annealing of gold coated GaAs substrates in N-2 ambient. GaAs substrates with different dopants were taken as the starting material to study the effect of doping on the growth and photoluminescence properties of beta-Ga2O3 nanostructures. The nanostructures were investigated by Grazing Incident X-ray Diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Energy Dispersive X-ray Spectroscopy, room temperature photoluminescence and optical absorbance. The selected area electron diffraction and High resolution-TEM observations suggest that both nanowires and nanobelts are single crystalline. Different growth directions were observed for nanowires and nanoribbons, indicating the different growth patterns of these nanostructures. The PL spectra of beta-Ga2O3 nanostructures exhibit a strong UV-blue emission band centered at 410 nm, 415 nm and 450 nm for differently doped GaAs substrates respectively. A weak red luminescence peak at 710 nm was also observed in all the samples. The optical absorbance spectrum showed intense absorption features in the UV spectral region. The growth and luminescence mechanism in beta-Ga2O3 nanostructures are also discussed. (C) 2011 Elsevier B.V. All rights reserved.