  The properties of InAs (110) surfaces have been investigated by means of
low-temperature scanning tunneling microscopy and spectroscopy. A technique for
ex-situ sulphur passivation has been developed to form an accumulation layer on
such a surface. Tunneling spectroscopy at 4.2 K shows the presence of 2D
subbands in the accumulation layer. Measurements in high-magnetic field
demonstrate Landau quantization of the energy spectrum, both in the 2D subbands
and the 3D bulk conduction band.
