Alloys of Transition Metal Trichalcogenides for New-class of Two-dimensional Materials with Infrared Bandgaps
Abstract
Overview and Merit: Historically, semiconductor science and technologies have been greatly advanced by alloying different semiconductors to achieve continuously tunable electronic structures, such as SixGe1-x for high-mobility transistors, AlxGa1-xAs for quantum structures, CuInxGa1-xSe2 for solar cells, InxGa1-xN for blue LEDs, and HgxCd1-xTe for infrared detectors. In this STIR project, we will extend this wisdom (alloying) to create a new family of two-dimensional (2D) flexible IR semiconductors with band gaps in the mid- and far-IR ranges that have potential to rival traditional HgxCd1-xTe (MCT) for advanced IR technologies. We propose to i) synthesize alloys of 2D transition metal trichalcogenides (TMTCs), such as 2D direct band gap NbxTi(1-x)S3 or TiSe3xTe3(1-x), that span the short to long wavelength IR range for the first time, and ii) characterize their structural, optical, electrical, and chemical properties using state-of-the-art structural, electronic, and optical characterization techniques available to our team. TMTCs are a new class of materials in which atoms are arranged to form weakly interacting chains that are confined in 2D. The presence of structural in-plane anisotropy in these materials results in direction-dependent material properties, which offer a new degree of freedom in that different material properties can be attained at different crystalline directions. TMTCs have many advantages, including high electronic mobility (theoretical estimation ~ 13,000 cm2 V-1 s-1 in the b-axis chain direction), mechanical flexibility, chemical stability, extreme thinness, and strong light-matter interactions in the quantum confinement limit, which distinguishes them from 2D systems and other traditional bulk IR material. Owing to their perfectly passivated surfaces, unlike MCTs, TMTCs do not suffer from bulk, surface, and interface instabilities. The successful outcome of this project will result in the introduction of a variety of environmentally stable 2D IR semiconductors, enhancing the potential for new physics and material properties associated with their unique quasi-1D structures that have yet to be experimentally explored. Impact: Synthetic atomic sheets of MX3 and their alloys can be potentially used for IR detectors operating in various modes. They can be also optimized for operating at the extremely wide range of the IR spectrum as well at temperatures ranging from that of liquid helium to room temperatures. Their material properties in the quantum confinement (2D) limit and their quasi-1D nature have a potential to make transformative impact in new generation IR technologies for military applications. In addition, entirely new applications in nanoelectronics, photonics, and energy conversion/storage are also expected of which the details and defense impact can only be appreciated after the results of the proposed effort are brought to light. This experimental effort pioneers a new material system and associated science that is exciting but also high-risk in the sense that it is largely an uncharted research exploration. However, in light DoDÕs continued efforts to seek new IR materials with unique properties for advanced military applications, the potential outcome of the proposed research significantly outweighs the associated risk.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 16, 2018
- Source ID
- W911NF1710255
Entities
People
- Sefaattin Tongay
Organizations
- Arizona State University
- Army Contracting Command
- United States Army