SusChEM: Sustainable III-V alloys using non-toxic bismuth as an alternative to HgCdTe

SusChEM: Sustainable III-V alloys using non-toxic bismuth as an alternative to HgCdTe SusChEM: Sustainable III-V alloys using non-toxic bismuth as an alternative to HgCdTe Project Summary Title: SusChEM: Sustainable III-V alloys using non-toxic bismuth as an alternative to toxic HgCdTe Overview: The objective of the proposed research is to theoretically and experimentally explore bismuth containing III-V semiconductor systems with narrow bandgaps for mid- and long-wavelength infrared device applications; which over the long-term provides an immense opportunity to develop an innovative class of semiconductor materials that can outperform and replace HgCdTe. In particular, InAs/InAsBi and GaSb/InAsBi superlattices strain balanced/lattice matched at the GaSb lattice constant, offer the prospect of alloying technologically important 6.1 semiconductors with semiconducting InAsBi (Bi mole fractions< 7.3%) and semimetallic InAsBi (Bi mole fractions > 7.3%). Calculations show that these superlattice material systems cover all wavelengths greater than 2 microns. Unlike bulk ternary materials, these systems have the advantage that arbitrarily thick, coherently strained layers can be grown at the readily accessible GaSb lattice constant without misfit dislocations. Consequently, as an alternative to HgCdTe, the proposed III-V alloys offer a sustainable material system that covers the technological wavelengths from mid to long infrared and beyond to zero bandgap and semimetal alloys. Intellectual Merit: The proposed research advances knowledge by alloying bismuth with arsenic on the group-V sublattice to develop materials in the technological important 8-12 micron atmospheric transmission window. In particular, the semimetallic compound InBi is alloyed with conventional III-V bulk and superlattice materials to create alloys with significant and highly exploitable electrical and optical properties. Furthermore, the proposed heterostructures offer a fascinating opportunity in terms of the design of the topography of the band structure. At the interface separating the two distinct materials, such as InAsBi and GaSb, the composite band structures allow varying both the effective bandgap and the electron-hole wavefunction overlap systematically. This provides the unique possibility to study quantum phase transitions of surface states, using the effective bandgap of the superlattice as a tuning parameter. Broader Impacts: The proposed research benefits society by advancing the materials knowledge base of sustainable III-V bismides to enable novel devices needed for present and future engineering grand challenges, such as i) mid and long infrared lasers and detectors for homeland security and pollution detection, ii) efficient infrared lasers and detectors for information and communication technology, and iii) photovoltaic and thermal photovoltaic solar-electrics for sustainable energy conversion. The proposed activity advances discovery and understanding while promoting teaching, training, and learning by i) connecting innovative and fundamental materials research and education, ii) bringing together researchers and students with broad areas of expertise to understand and discover how the addition of bismuth to narrow gap III-V semiconductors impacts band structure, bandgap, band offsets, and material performance; iii) providing data management and examination to guide the design and engineering of III-V bismuth superlattice materials and devices over a wide range of narrow bandgap energies, and iv) enabling the development of devices with exceptional performance. Moreover, the proposed activity adds value by enhancing science and technology through broader dissemination and understanding via i) face-to-face interaction at international workshops and conferences, ii) publication of student and researcher results in international journals and books, and iii) advancing data sharing and information exchange to further inspire innovative and rewarding research. In terms of sustainability, the proposed work examines and utilizes nontoxic bismuth as a constituent to broaden and enhance the performance of III-V semiconductor alloys for a safer and more secure replacement for the toxic element mercury and the very rare element tellurium in HgCdTe alloys.