Gate length scaling and threshold voltage control of double-gate MOSFETs

In the nanoscale regime, the double-gate MOSFET can provide superior short-channel behavior. For this structure, device scaling issues are explored. Gate length scaling will be limited by the ability to control off-state leakage current due to quantum tunneling and thermionic emission between the source and drain as well as band-to-band tunneling between the body and drain. Lateral S/D doping abruptness requirements for gate length scaling are examined. V_T control will be challenging as a single gate material for both NMOS and PMOS devices cannot provide low yet symmetrical V_T's. CMOS integration will thus require dual gate workfunction tuning, channel doping, or asymmetrical double-gates to adjust V_T. Advantages of using alternative channel materials to facilitate scaling are investigated.