Spectroscopy of one-dimensional subbands on InSb

Periodic metal stripes were prepared with grating constants a (approximately 250 nm) and small free widths w (approximately 100 nm) between stripes on InSb surfaces of metal-oxide-semiconductor structures. In such microstructures, electrons of fairly high mobility mu (approximately 20000 sq cm/V/s) are induced by a gate voltage into the channels between the metal stripes. The optical excitations are studied by far-infrared laser and Fourier spectroscopy. Cyclotron resonance experiments in quantizing magnetic fields show the importance of a lateral confining potential and a transition from two-dimensional to one-dimensional (1D) behavior when the magnetic field strength is decreased. Resonance energies are measured in zero magnetic fields as a function of the applied gate voltage V sub g and are discussed with the aid of simple theoretical pictures of the 1D quantization. The experimental results and their comparison with theoretically expected values demonstrate that quasi 1D subbands were created on InSb.