Dresden 2006 – scientific programme
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HL: Halbleiterphysik
HL 49: Devices
HL 49.4: Talk
Thursday, March 30, 2006, 16:00–16:15, BEY 154
Impact of the body thickness on the performance of silicon-on-insulator Schottky-barrier metal-oxide-semiconductor field-effect-transistors — •Joachim Knoch1, Min Zhang1, Siegfried Mantl1, and Joerg Appenzeller2 — 1Institute of Thin Films and Interfaces, ISG1-IT, Forschungszentrum Juelich, D-52425 Juelich — 2IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, USA
Schottky-barrier MOSFETs are an attractive alternative to conventional MOSFETs. Due to metallic electrodes in direct contact with the channel they offer low extrinsic parasitic resistances, excellent scalability down to smallest dimensions and easy processing. However, because of the Schottky barriers, SB-MOSFETs show an inferior intrinsic performance in terms of Ion/Ioff if compared to conventional devices: A high SB not only deteriorates the transistor’s on-state but also causes a poor subthreshold behavior. Here we present experimental and simulation results on ultrathin body (UTB) SOI SB-MOSFETs and show that the use of UTB SOI strongly improves the devices on- as well as off-state. An analytical approximation for the off-state is given that shows that the inverse subthreshold slope scales as the square-root of the SOI thickness. In addition, threshold voltage variations that appear in UTB SOI SB-MOSFETs will be discussed. Two different mechanisms are responsible for this, namely the above mentioned strong dependence of the device performance on the SOI thickness and vertical quantization due to the confinement of carriers between the gate and the buried oxide. Design rules are given of how to avoid too large threshold voltage variations and at the same time achieve a good device performance.