Quantum-ballistic transport in an etch-defined Si/SiGe quantum point contact

Ballistic constrictions are fabricated on a high-mobility Si/SiGe strained-layer heterostructure which exhibit conductance quantization in units of 4e2/h at T=4.2K. Under finite drain voltage a half-plateau develops at 2e2/h and a series of oscillations appear which enable us to extract the energy separation ΔEN+1,N between successive one-dimensional subbands. The result is ΔE2,1=2.0meV and ΔE3,2=1.4meV. © 2002 American Institute of Physics.