Electrical characterization of Si/Si_0.7Ge_0.3 quantum well wires fabricated by low damage CF₄ reactive ion etching

Abstract

Nearly damage free etching of a high mobility Si/SiGe heterostructure is obtained by using very low power reactive ion etching and precise end-point detection. Conductance versus wire width plots of 0.08 μm to 1 μm wide Si/SiGe quantum well wires show the combined nonconducting width at the edges to be 0.13 μm ± 0.01 μm, in agreement with weak localization studies. Mobility vs. sheet concentration measurements indicate little or no degradation in electron mobility after processing. Furthermore, our study demonstrates very little difference between wires with and without post-RIE (reactive-ion etching) annealing and passivation treatment. Application of this process for fabricating point contacts and other quantum effect devices is demonstrated.