The first principle study of atomistic, electronic, and optical structure of mercury telluride (HgTe) nanocrystals (NC)
Yunhua Xing a, Nuri Yazdani a, Vanessa Wood a
a Institute of Electronics (IfE), D-ITET, ETHZ
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS23 & Sustainable Technology Forum València (STECH23) (MATSUS23)
#NCFun23 - Fundamental Processes in Nanocrystals and 2D Materials
VALÈNCIA, Spain, 2023 March 6th - 10th
Organizers: Valerio Pinchetti and Shalini Singh
Poster, Yunhua Xing, 365
Publication date: 22nd December 2022

Densely packed conductive films of mercury-telluride (HgTe) nanocrystals (NC) have, over the past decades, demonstrated great potential as low-cost-high-performing photodetectors, tunable over a spectral range from the short-wave-infrared to terahertz frequencies.[1,2,3] While the technological potential of these materials is clear, many fundamental questions remain concerning the electronic/optical structure of these nanocrystals and how they derive from semimetal bulk HgTe, and on the nature of charge carrier transport and non-radiative recombination in thin films of these NCs. Here we present a systematic study into these properties based on density functional theory (DFT) calculations. We constructed HgTe NC in series of different sizes, shapes, surface terminations and dopants/defects, which are consistent with experimental observations.[3,4,5] By applying DFT calculations on these NC series, we found that surface distortion of HgTe NC facilitates the opening of HOMO-LUMO gap up to 1eV, regardless of quantum confinement effect [3,6]. X-ray powder diffraction was performed as the proof of concept. We further show how surface termination and dopants/defects influences the electronic and optical structures and coupling by extracting and comparing electronic wavefunctions of the NCs. We compare the optical coupling strength of interband and intraband (1s->1p) transitions. And, we address the impact of dopants/defects on electronic coupling between neighboring HgTe NCs, which plays an important role on the relative magnitude of hole and electron mobility. The findings of our study, in combination with experimental characterization efforts, will guide the optimization of next generation nanocrystal-based IR photodetectors.

We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info