It is expected that the Moore's law would be broken in Si-based technology in the near future. To overcome this issue, we have performed research and development of various nanodevices based on nanostructured materials.
Recent progress in silicon photonics has dramatically advanced the possible realization of heterogeneous logic circuits. A variety of Boolean optoelectronic circuits have been proposed5. In this context, experimental investigation of logic operations with both optical and electrical inputs in chip-integrable devices is highly desirable. Here, we present a new kind of photodiode-based logic device using scalable heterojunctions of carbon nanotubes and silicon, the output currents of which can be manipulated completely by both optical and electrical inputs. This provides a novel platform for heterogeneous optoelectronic logic elements with voltage-switchable photocurrent responsivity of > 1 AW-1, photovoltage responsivity of >1×105 VW-1, electrical on/off ratios of >1×105 and optical on/off ratios of >1×104. To demonstrate their scalability, we fabricated a large array of photoactive elements on a centimetre-scalewafer. We also present bidirectional phototransistors and novel clock-triggerable logic elements such as a mixed optoelectronic AND gate, a 2-bit optoelectronic ADDER/OR gate and a 4-bit optoelectronic digital-to-analog converter.
We have reported the large-scale assembly of type-switchable field effect transistors (FETs) based on carbon nanotubes (CNTs) and nanoparticles (NPs). In this device, the charges stored in NPs adjacent to ambipolar CNT channels were adjusted to control the carrier type and density in the channels. We demonstrated the real-time reconfiguration of individual FET types and logic circuit functionality. Theoretical simulation of a model system was provided to explain this doping effect. This work takes advantage of the ambipolar properties of CNTs and opens up the possibility to build new types of devices with reconfigurable functionalities.
Based on the percolation theory, we have performed device simulations on network devices. We have found that it is possible to make semiconducting devices out of mixture of metallic and semiconducting nanotubes.
We investigate the internal dynamics of a related model system, consisting of a K@C+60 endohedral complex enclosed in a C480 nanocapsule. We show this to be a tunable two-level system, where transitions between the two states can be induced by applying an electric field between the C480 end caps, and discuss its potential application as a nonvolatile memory element.