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Effects of interface roughness and conducting filaments in metal–oxide–semiconductor tunnel structures

Ting, D. Z.-Y. and McGill, T. C. (1998) Effects of interface roughness and conducting filaments in metal–oxide–semiconductor tunnel structures. Journal of Vacuum Science and Technology B, 16 (4). pp. 2182-2187. ISSN 1071-1023. doi:10.1116/1.590297.

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The current–voltage characteristics of n+ poly-Si/SiO2/p-Si tunnel structures containing nonuniform ultrathin oxide layers are studied using three-dimensional quantum mechanical scattering calculations. We find that, in general, roughness at the Si/SiO2 interface renders the oxide layer more permeable. In the direct-tunneling regime, interface roughness induces lateral localization of wave functions, which leads to preferential current paths. But in the Fowler–Nordheim tunneling regime it affects transport primarily through scattering. These two distinct mechanisms lead to opposite current density dependencies on island size. We have also examined oxide-embedded conducting filaments, and found that they act as highly efficient localized conduction paths and lead to dramatic increases in current densities. Depending on the filament length, our model can mimic experimental current voltage for ultrathin oxides having undergone either quasibreakdown or breakdown. We also found that the lower bias current densities in the structure with long filaments are greatly enhanced by resonant tunneling through states identified as quantum dots, and that this current enhancement is highly temperature dependent. We also report on the dependence of current–voltage characteristics on filament diameter size and filament density.

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Additional Information:©1998 American Vacuum Society. (Received 21 January 1998; accepted 21 May 1998) The authors would like to thank O.J. Marsh, E.S. Daniel, and Z.Q. Zhang for helpful discussions, and M.A. Barton for technical assistance. This work was supported by the U.S. Office of Naval Research (ONR) under Grant No. N00014-89-J-1141, the U.S. Air Force Office of Scientific Research (AFOSR) under Grant No. F49620-96-1-0021, and by the ROC National Science Council under Grant No. NSC 87-2112-M-007-005.
Subject Keywords:silicon; elemental semiconductors; silicon compounds; MIS structures; interface structure; electrical conductivity; semiconductor-insulator-semiconductor structures; tunnelling; island structure; interface states; semiconductor quantum dots; quantum interference phenomena; electric breakdown
Issue or Number:4
Record Number:CaltechAUTHORS:TINjvstb98
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10840
Deposited By: Archive Administrator
Deposited On:12 Jun 2008
Last Modified:08 Nov 2021 21:11

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