This exploratory study on vertical, undoped silicon nanowire transistors shows less power dissipation with respect to the bulk and SOI MOS transistors while yielding comparable performance. The design cycle starts with determining individual metal gate work functions for each nMOS and pMOS transistor as a function of wire radius to produce a 300 mV threshold voltage. Wire radius and effective channel length are both varied until a common body geometry is determined for both nMOS and pMOS transistors to limit OFF currents under 1 pA while producing highest ON currents. DC characteristics of the optimum and -channel transistors such as threshold voltage roll-off, DIBL and subthreshold slope are measured; simple CMOS gates including an inverter, 2-and 3-input NAND, NOR, and XOR gates, and full adder are built to measure the transient performance, power dissipation and layout area. Postlayout simulation results indicate that the worst case delay for a full adder circuit is 8.5 ps at no load and increases by 0.15 ps/aF; worst case power dissipation of the same circuit is 23.6 nW at no load and increases by 4.04 nW/aF at 1 GHz. The full adder layout area occupies approximately 0.11 m 2 .Index Terms-Low-power very large scale integration (VLSI), metal-gate transistors, nanowire transistors, vertical silicon transistors.

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Evidence of native gallium antisite defects in semiinsulating liquidencapsulated Czochralskigrown GaAsThe shallow defect evolution in Si-implanted and -annealed liquid-encapsulated Czochralskigrown GaAs is investigated by photoluminescence experiments. Three major emission lines are found. The first emission line located at 1.492 eV corresponds to the Si Ga -CAS radiative recombination. The remaining two lines located at 1.44 and 1.40 eV are shown to correspond to Gal-Si.",s and VAs-Si As radiative recombinations, respectively. The effects of these three shallow centers on the silicon activation efficiency are discussed with respect to different annealing and implantation conditions. 1246

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