Communications systems such as WiFi, GPS, wireless sensor networks, and radio frequency electronics are critical to the nation?s infrastructure and have had a transformative impact on daily life. However, existing applications of wireless technologies are often limited by the power consumption and speed of the underlying electronic switches, or transistors, that send and receive signals. Furthermore, current classes of transistors must be integrated into complex circuits to perform simple functions. This award supports the fundamental research necessary to make new classes of transistors that can improve the performance of existing communications technologies and open up new applications by enabling simplified circuit designs on flexible substrates. The development of inexpensive and scalable approaches to new transistor materials will facilitate the incorporation of these devices into new technologies. Computer models of novel transistors and communications circuits will be shared with industry partners to facilitate the transfer of knowledge and capabilities to industry, growing the high-tech economy. Outreach programs including cooperation with the Chicago Museum of Science and Industry will recruit a broad group of young people to careers in science and technology crucial to the nation?s economy and defense.
The objective of the proposed work is to create, characterize, understand, and exploit new classes of electronic and optoelectronic devices by integrating promising two-dimensional monolayer transition metal dichalcogenides with other low dimensional semiconductors including p-type organic semiconductors, sorted semiconducting single walled carbon nanotubes, and other two-dimensional materials. The project will fabricate novel ultrathin p-n heterojunctions of mixed dimensionality 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 ultrathin dichalcogenides by atomic layer deposition over large areas at reduced temperatures. To understand how the device physics leads to new properties and circuit performance, phenomenological models will be integrated into industry accepted nanodevice simulators, and a compact model will be developed. The fundamental knowledge and predictive models of ultrathin heterojunctions will expand engineering frontiers through quantitative understanding of charge transport, the demonstration of novel device characteristics, such as the recently discovered anti-ambipolar behavior, and the exploitation of these behaviors to create novel electronic circuits on flexible substrates with simpler designs and fewer elements than conventional unipolar field effect transistor-based circuits.
