Effect of a silicon interlayer in low-temperature poly-SiGe thin film transistors

Albert W. Wang; Krishna C. Saraswat

doi:10.1117/12.270288

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10 April 1997 Effect of a silicon interlayer in low-temperature poly-SiGe thin film transistors

Albert W. Wang, Krishna C. Saraswat

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Proceedings Volume 3014, Active Matrix Liquid Crystal Displays Technology and Applications; (1997) https://doi.org/10.1117/12.270288
Event: Electronic Imaging '97, 1997, San Jose, CA, United States

Abstract

Polycrystalline silicon-germanium TFT technology has potential for flat panel display applications because of its reduced thermal budget. Previously, single-crystal SiGe MOSFETs have used a silicon cap or interlayer between the gate oxide and the channel to improve the gate oxide interface and device performance. Here the use of a Si interlayer, ranging from 0 to 100 angstrom in thickness, in poly-SiGe TFTs fabricated by a low-temperature process is investigated. It is found that performance is significantly affected by the presence of the interlayer. The changes are due to the improvement of the SiO₂-SiGe interface and the division of the drain current among the Si interlayer and SiGe film, which have different electrical properties. NMOS mobility peaks at 36 cm²/Vs with a 50 angstrom interlayer, as compared to 22 cm$_2)/Vs without an interlayer and 28 cm²/Vs in a pure Si device. Other NMOS performance parameters improve as the interlayer thickness increase.In contrast, PMOS performance initially improves when the interlayer is introduced, but then declines as the interlayer thickness increases.

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Albert W. Wang and Krishna C. Saraswat "Effect of a silicon interlayer in low-temperature poly-SiGe thin film transistors", Proc. SPIE 3014, Active Matrix Liquid Crystal Displays Technology and Applications, (10 April 1997); https://doi.org/10.1117/12.270288

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