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Room-temperature electroluminescence from electron-hole plasmas in the metal-oxide-silicon tunneling diodes Conjugated polymers, with molecular orbitals delocalized along the polymer chain, are useful organic semiconductors that provide the possibility of molecular electronics for low-power organic-based memory and logic. Quantum functional devices based upon carrier tunneling processes open vistas into very efficient and low-power consumption circuitry that would be ideal for these applications. We demonstrate here strong room temperature negative differential resistance ͑NDR͒ for poly͓2-methoxy-5-͑2Ј-ethyl-hexyloxy͒-1,4-phenylenevinylene͔ ͑MEH-PPV͒ polymer tunnel diodes ͑PTD͒ using a thin TiO 2 tunneling layer ͑ϳ2-8 nm͒ sandwiched between the MEH-PPV and the indium tin oxide anode. A key advantage is the pronounced NDR using a thick polymer layer with a large active area, circumnavigating the need for molecularly-sized junctions. Current-voltage measurements show large and reproducible NDR with a PVCR as high as 53 at room temperature. We also demonstrate basic logic circuit operation using a pair of these PTDs connected in series to form a monostable-bistable transition logic element ͑MOBILE͒ latch.

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Si-based resonant bipolar transistors are demonstrated by the monolithic vertical integration of Si-based resonant interband tunnel diodes atop the emitter of Si/SiGe heterojunction bipolar transistors (HBTs) on a silicon substrate. In the common emitter configuration, IC versus VCE shows negative differential resistance characteristics. The resulting characteristics are adjustable peak-to-valley current ratios, including infinite and negative values, and tailorable peak current densities by the control of the HBT base current under room temperature operation. With the integrated RITD-HBT combination, latching properties which are the key operating principle for high-speed mixed-signal, memory, and logic circuitry, are experimentally demonstrated.

Room-temperature I–V characteristics of epitaxially grown Si/SiGe resonant interband tunneling diodes (RITDs) with extremely high peak current densities are presented. By optimizing the physical design, doping concentrations, and post-growth anneal temperatures, RITDs having peak current densities over 150 kA/cm2, peak-to-valley current ratios (PVCRs) greater than 2, and an estimated speed index of 34 mV/ps have been obtained. The interplay among the conditions to achieve maximum current density and highest PVCR is discussed. This result demonstrates the high potential of this type of Si-based tunnel diode for high-power mixed-signal applications.