Quasi two-dimensional accumulation layer on n--type InAs in tipped magnetic fields /

Abstract

With the magnetic field parallel to the surface, non-periodic structure in the transconductance is observed and attributed to the total depopulation of the subbands as they are pushed up in energy above the Fermi level. As the sample temperature is increased the amplitude of this structure decreases, which allows a measurement of the subband energy.

The electron gas formed at the surface of an n-type InAs MOSFET is quasi two-dimensional. The period in inverse magnetic field strength of the Shubnikov-de Haas oscillations allows a determination of the 2D subband number density. Tipping the magnetic field away from the surface normal decreases the subband population: the component of the magnetic field parallel to the accumulation layer raises the subband energies, hence depopulating the excited states, and the perpendicular field component gives rise to the SdH oscillations from which the population can be determined.

Also observed in our data is the magnetic freeze-out of 2D impurity band conduction at the oxide-semiconductor interface.