Participant Support Costs

OVERVIEW: The objective of the proposed work is to create new classes of electronic and optoelectronic devices by integrating promising 2D monolayer transition metal dichalcogenides (TMDCs) with other low dimensional semiconductors including p-type organic semiconductors (0D), semiconductor nanowires (1D), sorted semiconducting single walled carbon nanotubes (1D), and other TMDCs (2D). The project will fabricate novel ultrathin p-n heterojunctions of mixed dimensionality (2D + 0/1/2D) that exhibit unique and quantitatively advantageous properties arising from gate transparency and flexibility, and characterize the devices with advanced scanned probe techniques in addition to conventional current and capacitance versus voltage measurements. Custom chemical precursors will be designed and synthesized with the goal of achieving scalable growth and fabrication of TMDCs by atomic layer deposition. To understand how new device physics leads to new device properties and circuit performance, new phenomenological models will be integrated into an industry accepted nanodevice simulator (NEMO-5). INTELLECTUAL MERIT: The p-n junction is the cornerstone of modern device engineering, but conventional bulk and thin film semiconductors limit the geometry and functionality of p-n junction based devices. The proposed work leverages the recent discovery of gate tunable rectification and novel anti-ambipolar transfer characteristics in an ultrathin, gate-tunable 1D+2D p-n junctions consisting of a p-type semiconducting single walled carbon nanotube (SWCNT) thin film deposited on n-type MoS2. This 1D+2D device suggests great potential for ultrathin van der Waals heterojunctions that are atomically abrupt, flexible, transparent, and highly tunable by gate voltages and chemistry. The fundamental knowledge and predictive models of the behavior of van der Waals p-n heterojunctions will expand engineering frontiers through quantitative understanding of the transport characteristics within 2D materials and junctions, demonstration of anti-ambipolar and other novel device characteristics, and the exploitation of these junctions in logic and optoelectronic devices on flexible substrates. In particular, anti-ambipolar behavior will be exploited to create novel electronic circuits with simpler designs and fewer elements than conventional unipolar field effect transistor (FET) based circuits. BROADER IMPACTS: Advances in engineering research frontiers that improve existing communications technologies or enable deployment of communication technologies in new contexts have the potential for major impact on both consumer-oriented and defense oriented industries. 2D+0/1/2D heterojunctions are enabling in this respect: anti-ambipolar behavior can be exploited to create novel electronic circuits on flexible substrates with simpler designs and fewer elements than conventional unipolar field effect transistor (FET) based circuits. Applications range from ultrafast, flexible photodetectors to phase shift keying circuits in communications systems such as WiFi, GPS, wireless sensor networks, and radio frequency electronics. The proposed approach to engineering research will facilitate the transfer of knowledge and capabilities to industry. The materials processing approaches enable the scaling up of devices and circuits over large areas while also enabling fabrication on polymeric/flexible substrates at a low cost with all key device constituents available in solution phase. The computational device simulation effort will center on NEMO5, which is used and funded by mo