Photoconductance Decay Characterization of 3D Multi-Fin Silicon on SOI Substrates

This letter is concerned with the electrical characterization of 3D fin-shaped silicon used as a channel in novel transistor architectures. This approach adapts photoconductance decay minority carrier measurement methodology to the needs of electrical characterization of fin-shaped semiconductor materials systems. The results obtained indicate as high as threefold decrease in the minority carrier lifetime in the fin-shaped Si as compared with the same active planar Si prior to fins definition (from τ∼45μs to τ∼ 15μs). A cause of this decrease is significant expansion of the effective surface area of the finned samples and the resulting increase in recombination sites related to the structurally disordered sidewalls of the fins formed via etching. Hydrogen termination of the finned surfaces did not provide long-term passivation of the surfaces, which was accomplished only by atomic layer deposition of 3-nm-thick layer of Al₂O₃.