Spectroscopy of one-dimensional subbands on InSb

By means of high resolution optical lithography two-dimensional (2D) electron inversion layers in metal-oxide-semiconductor (MOS) structures on InSb are laterally confined to narrow channels. The widths of the channels (w≈100nm) are comparable to the de-Broglie wavelength of the electrons and formation of one-dimensional (1D) subbands results. This is verified by direct spectroscopy of intersubband transitions between the 1D subbands at far-infrared frequencies. Cyclotron resonance experiments also show the importance of the lateral confining potential. In particular, the transition from 1D to 2D electronic behavior is observed when the magnetic field strength is increased and the cyclotron radius ℓ becomes much less than the channel width w.