Scanning tunneling microscopy (STM) and tunneling I–V measurements of n and p-type GaAs(001)2×4 surfaces are reported. These substrates were prepared using both migration enhanced epitaxy and conventional molecular-beam epitaxy techniques. A puzzling feature of this surface is that, while it is difficult to obtain empty state images with n-type samples, images can be obtained at positive and negative sample bias on p-type substrates equally well. Neglecting the contribution from states at the surface, we demonstrate that providing the Fermi level remains pinned midgap, the tunnel current should be independent of the bulk dopant. Using the method of dual voltage STM imaging, we verify that, unlike GaAs(110), both the filled and empty state images of p-doped samples are dominated by As related states. We also observe kink defects on the p-type surfaces that have been reported on n-doped samples. We find the number density of kinks is decreased by terminating the epitaxial growth with a layer of intrinsic material, which supports the view that the surface forms these kink defects to accept charge from the dopant atoms in the bulk, acting to pin the Fermi level.