Tham khảo tài liệu 'nanotechnology and nanoelectronics - materials, devices, measurement techniques part 13', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 234 9 Innovative Electronic Devices Based on Nanostructures g h Fig. Fabrication process and SEM images of a carbon nanotube based gated field emitter array from 390 Carbon Nanotube Transistors The above-mentioned very high values of the charge carrier mobilities in semiconducting carbon nanotubes together with the small device dimensions make CNT based devices very interesting for microelectronic applications. So far field effect type transistors have mostly been implemented 389 390 391 because carbon nanotubes exhibit very high hole mobilities in particular. It should however also be mentioned that first experiments to realize a bipolar p-n-p transistor were successful 393 . Fig. a AFM image b schematic structure and band diagrams without c and with d applied source-drain voltage of a TUBEFET from 389 Carbon Nanotube Devices 235 In Fig. the structure and the atomic force microscope AFM image of a so-called TUBEFET are shown. On a silicon wafer covered with a thermal SiO2 layer that serve as backside gate and gate insulator respectively platinum Pt electrodes are deposited that form the source and drain contact. Subsequently the single wall carbon nanotubes are deposited or grown connecting the two platinum contacts. The room temperature characteristics of this TUBEFET are illustrated in Fig. . For positive voltages applied between drain and source contact a clear threshold voltage for conduction has been observed whose value increases with increasing gate voltage. For negative voltages applied between drain and source ohmic behavior has been found. Furthermore it can be seen that a 10 V change of the gate voltage results in a variation of the channel conductance of more than six orders of magnitude. One of the main problems regarding the fabrication of integrated circuits using CNT transistors is the limited reproducibility of the CNT growth process. An alternative approach to lateral integration is the manufacturing of arrays of CNTs
