Ultralow-power organic complementary circuits

Abstract

The prospect of using low-temperature processable organic semiconductors to implement transistors, circuits, displays and sensors on arbitrary substrates, such as glass or plastics, offers enormous potential for a wide range of electronic products. Of particular interest are portable devices that can be powered by small batteries or by near-field radio-frequency coupling. The main problem with existing approaches is the large power consumption of conventional organic circuits, which makes battery-powered applications problematic, if not impossible. Here we demonstrate an organic circuit with very low power consumption that uses a self-assembled monolayer gate dielectric and two different air-stable molecular semiconductors (pentacene and hexadecafluorocopperphthalocyanine, F16CuPc). The monolayer dielectric is grown on patterned metal gates at room temperature and is optimized to provide a large gate capacitance and low gate leakage currents. By combining low-voltage p-channel and n-channel organic thin-film transistors in a complementary circuit design, the static currents are reduced to below 100 pA per logic gate. We have fabricated complementary inverters, NAND gates, and ring oscillators that operate with supply voltages between 1.5 and 3 V and have a static power consumption of less than 1 nW per logic gate. These organic circuits are thus well suited for battery-powered systems such as portable display devices and large-surface sensor networks as well as for radio-frequency identification tags with extended operating range.

Molecules on Si: Electronics with Chemistry

“…1a), which resemble a known and well-modeled device, the ultra-thin MIS that was investigated with SiO 2 as insulator. Remarkably, an MIS structure with an alkyl monolayer insulator shows reproducibility and uniformity that are superior to what is obtained with inorganic oxides of similar width [40,56] and for which, even if the alkyl monolayer width is shrunk down to a C 1 (ÀCH 3 ) layer, MIS-like behavior persists. [19,20] The dielectric strength of alkyl monolayers on either Si [57,58] or Au [59] is about 10-20 MV cm À1 , twice that of bulk SiO 2 , [41] 10 times that of bulk polyethylene, [57] and comparable to that of alkyl monolayers on SiOx.…”

“…For most metals (except the most noble ones, Au and Pt) and compound semiconductors, residual surface oxides are inevitable and fairly unstable, also because of the rich binding chemistry of surface oxides and hydroxides. [37,38] While that same chemistry can be put to good use in molecular electronics (e.g., silanes on SiOx, [39] phosphonates on Al 2 O 3 [40] and GaAs [36] ), below a minimal oxide width the reproducibility and stability of an oxidized surface is poor. An electronically ill-defined oxide also complicates junction modeling.…”

Flexible and low-voltage integrated circuits constructed from high-performance nanocrystal transistors

“…For example, although excellent mobilities have been observed with molecular metal chalcogenide complexes 18,19 , these NCs are dissolved in hydrazine, an extremely caustic solvent that is not compatible with flexible plastics. In addition, as a wide range of flexible electronic applications are typically powered by small thin-film batteries or radio frequency fields 22,23 , it is necessary to show the scalability of these colloidal inks to minimize energy consumption. We recently demonstrated low-voltage operation of flexible colloidal nanowire FETs using thin Al 2 O 3 as our robust, high capacitance and low-leakage gate dielectric material compatible with plastics 24 .…”

Highly Reliable Carbon Nanotube Transistors with Patterned Gates and Molecular Gate Dielectric

“…9,13 Theoretical work has shown that DIBL in short-channel SWCNT FETs can be reduced by implementing a double-gate, triple-gate, or surround-gate device structure. 17 Combining patterned bottom gate electrodes 12 with a thin, SAM-based gate dielectric 16 offers a number of advantages. First, it allows the integration of individually addressable, low-voltage transistors into large-scale integrated circuits on arbitrary substrates, including glass or flexible plastics, which is not possible with a global, unpatterned gate (and hence not possible with a SiO 2 dielectric that is thermally grown on a doped silicon wafer).…”

“…Pentacene thin-film transistors (TFTs) show excellent initial performance with carrier mobility around 1 cm 2 /Vs, transconductance exceeding 40 µS/mm, subthreshold swing of 100 mV/decade, and on/off ratio of 10 7 or greater. 16 But pentacene is readily oxidized in the presence of ambient species, yielding molecules such as 6,13-pentacenequinone, which act as charge traps or scattering sites in the semiconductor. 27 Consequently, the transconductance of pentacene transistors exposed to air decays rapidly and significantly.…”