i 回1e c9989≈ d &agp Position (um) igure 3.(a) Schematic of multiple FET array on a single ultralong p-siNw.(b)Dark-field optical image of multiple FETs defined by electron beam lithography. The p-siNW is horizontal in the image and the vertical lines crossing the nw correspond to S/D electrodes with um width/2 um separation; scale bar is 100 um. The dashed white rectangle corresponds to a similar area shown schematically in(a).(c) Position vs Ip at VD=1 Vand VG=-10 V measured from the multiple FETs defined on the single p-SiNW in the image.(d) Position vS Gm at VD =1 v(e)Position vs vth. b 1300 (1) (3) 1200 1100 1000 2000400060008000 Figure 4.(a) Optical image of a multiple sensor array with similar source-drain dimensions as in Figure 3b; scale bar, 100 um. The red blue, and green circles highlight regions from which sensing data were recorded. (b)Conductance-versus-time data measured simultaneously from three Fet devices from the red, blue, and green regions of the device array. The sinw FET array was functionalized with mAb for PSA, and the data were recorded by alternating delivery of target solutions(PSA or BSA)and buffer solution where vertical arrows correspond to the delivery of (1)20 pg/ml PSA, (2)500 pg/ml PSA, (3)10 ng/ml PSA, (4)10 ug/ml BSA, and (5)20 pg/ml PSA solutions. The functionalization and measurement procedures were the same as reported previously 3 SiNWs are electrically homogeneous and yield device porated in a uniform manner during nanocluster-catalyzed reproducibility higher than achieved from single Nw-based VLS growth FETs. Last, these measurements also suggest that the active The ability to define large numbers of functional FETs boron dopant yielding the p-type behavior must be incor- along single ultralong NWs can open up new opportunities ano Lett, Vol. 8, No. 9, 2008SiNWs are electrically homogeneous and yield device reproducibility higher than achieved from single NW-based FETs. Last, these measurements also suggest that the active boron dopant yielding the p-type behavior must be incor￾porated in a uniform manner during nanocluster-catalyzed VLS growth. The ability to define large numbers of functional FETs along single ultralong NWs can open up new opportunities Figure 3. (a) Schematic of multiple FET array on a single ultralong p-SiNW. (b) Dark-field optical image of multiple FETs defined by electron beam lithography. The p-SiNW is horizontal in the image and the vertical lines crossing the NW correspond to S/D electrodes with 2 µm width/2 µm separation; scale bar is 100 µm. The dashed white rectangle corresponds to a similar area shown schematically in (a). (c) Position vs ID at VD ) 1 V and VG ) -10 V measured from the multiple FETs defined on the single p-SiNW in the image. (d) Position vs GM at VD ) 1 V. (e) Position vs Vth. Figure 4. (a) Optical image of a multiple sensor array with similar source-drain dimensions as in Figure 3b; scale bar, 100 µm. The red, blue, and green circles highlight regions from which sensing data were recorded. (b) Conductance-versus-time data measured simultaneously from three FET devices from the red, blue, and green regions of the device array. The SiNW FET array was functionalized with mAb for PSA, and the data were recorded by alternating delivery of target solutions (PSA or BSA) and buffer solution where vertical arrows correspond to the delivery of (1) 20 pg/ml PSA, (2) 500 pg/ml PSA, (3) 10 ng/ml PSA, (4) 10 µg/ml BSA, and (5) 20 pg/ml PSA solutions. The functionalization and measurement procedures were the same as reported previously.13,17 Nano Lett., Vol. 8, No. 9, 2008 3007