HfxZr1-xO2 Solid Solution Nanoclusters with Size-Specific Bandgaps

Combining zirconia and hafnia into a bimetallic oxide such as HZO (Hf0.5Zr0.5O2) has attracted a lot of interest because the introduction of a novel orthorhombic phase with intrinsic polarization in HZO has led to strong ferroelectric properties. Here, we use a gas-phase aggregation technique to produce size-specific HfxZr1-xO2 (x 10 nm. For the single-crystalline HfxZr1-xO2 NCs, we observe, for the first time for NCs, the special orthorhombic (Pbc21) structure found previously only in the HZO film prepared under extreme conditions. The measured bandgaps of these NCs are found to increase with the cluster size, in contrast to the increase in the bandgap with decreasing size generally found in NCs. The X-ray photoelectron spectra clearly show, in the Zr 3d region, components that can be attributed to oxygen vacancy defects and the substitution of Hf for Zr in the lattice. A new model involving Hf-induced electron polarization is proposed to describe the physical and electronic structures of these novel bimetallic hybrid oxide NCs. This work establishes a general formation protocol for other hybrid semiconductor NCs, while the HfxZr1-xO2 (x © 2024 American Chemical Society.