Vanadium dioxide (VO2) is a well‐studied Mott‐insulator because of the very abrupt physical property switching during its semiconductor‐to‐metal transition (SMT) around 341 K (68 °C). In this work, through novel oxide‐metal nanocomposite designs (i.e., Au:VO2and Pt:VO2), a very broad range of SMT temperature tuning from
Mott insulator VO2exhibits an ultrafast and reversible semiconductor‐to‐metal transition (SMT) near 340 K (67 °C). In order to fulfill the multifunctional device applications, effective transition temperature (
- PAR ID:
- 10464635
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Physics Research
- Volume:
- 2
- Issue:
- 12
- ISSN:
- 2751-1200
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract ≈ 323.5 to≈ 366.7 K has been achieved by varying the metallic secondary phase in the nanocomposites (i.e., Au:VO2and Pt:VO2thin films, respectively). More surprisingly, the SMTT ccan be further lowered to≈ 301.8 K (near room temperature) by reducing the Au particle size from 11.7 to 1.7 nm. All the VO2nanocomposite thin films maintain superior phase transition performance, i.e., large transition amplitude, very sharp transition, and narrow width of thermal hysteresis. Correspondingly, a twofold variation of the complex dielectric function has been demonstrated in these metal‐VO2nanocomposites. The wide range physical property tuning is attributed to the band structure reconstruction at the metal‐VO2phase boundaries. This demonstration paved a novel approach for tuning the phase transition property of Mott‐insulating materials to near room temperature transition, which is important for sensors, electrical switches, smart windows, and actuators. -
null (Ed.)A phase transition material, VO 2 , with a semiconductor-to-metal transition (SMT) near 341 K (68 °C) has attracted significant research interest because of drastic changes in its electrical resistivity and optical dielectric properties. To address its application needs at specific temperatures, tunable SMT temperatures are highly desired. In this work, effective transition temperature ( T c ) tuning of VO 2 has been demonstrated via a novel Pt : VO 2 nanocomposite design, i.e. , uniform Pt nanoparticles (NPs) embedded in the VO 2 matrix. Interestingly, a bidirectional tuning has been achieved, i.e. , the transition temperature can be systematically tuned to as low as 329.16 K or as high as 360.74 K, with the average diameter of Pt NPs increasing from 1.56 to 4.26 nm. Optical properties, including transmittance ( T %) and dielectric permittivity ( ε ′) were all effectively tuned accordingly. All Pt : VO 2 nanocomposite thin films maintain reasonable SMT properties, i.e. sharp phase transition and narrow width of thermal hysteresis. The bidirectional T c tuning is attributed to two factors: the reconstruction of the band structure at the Pt : VO 2 interface and the change of the Pt : VO 2 phase boundary density. This demonstration sheds light on phase transition tuning of VO 2 at both room temperature and high temperature, which provides a promising approach for VO 2 -based novel electronics and photonics operating under specific temperatures.more » « less
-
more » « less
Abstract Photonic integrated circuits require various optical materials with versatile optical properties and easy on‐chip device integration. To address such needs, a well‐designed nanoscale metal‐oxide metamaterial, that is, plasmonic Au nanoparticles embedded in nonlinear LiNbO3(LNO) matrix, is demonstrated with tailorable optical response. Specifically, epitaxial and single‐domain LNO thin films with tailored Au nanoparticle morphologies (i.e., various nanoparticle sizes and densities), are grown by a pulsed laser deposition method. The optical measurement presents obvious surface plasmon resonance and dramatically varied complex dielectric function because of the embedded Au nanoparticles, and its response can be well tailored by varying the size and density of Au nanoparticles. An optical waveguide structure based on the thin film stacks of a‐Si on SiO2/Au‐LNO is fabricated and exhibits low optical dispersion with an optimized evanescent field staying in the LNO‐Au active layer. The hybrid Au‐LNO metamaterial thin films provide a novel platform for tunable optical materials and their future on‐chip integrations in photonic‐based integrated circuits.
-
more » « less
Abstract Straining the vanadium dimers along the rutile
c ‐axis can be used to tune the metal‐to‐insulator transition (MIT) of VO2but has thus far been limited to TiO2substrates. In this work VO2/MgF2epitaxial films are grown via molecular beam epitaxy (MBE) to strain engineer the transition temperature (T MIT). First, growth parameters are optimized by varying the synthesis temperature of the MgF2(001) substrate (T S) using a combination of X‐ray diffraction techniques, temperature dependent transport, and soft X‐ray photoelectron spectroscopy. It is determined thatT Svalues greater than 350 °C induce Mg and F interdiffusion and ultimately the relaxation of the VO2layer. Using the optimized growth temperature, VO2/MgF2(101) and (110) films are then synthesized. The three film orientations display MITs with transition temperatures in the range of 15–60 °C through precise strain engineering. -
more » « less
The integration of nanocomposite thin films with combined multifunctionalities on flexible substrates is desired for flexible device design and applications. For example, combined plasmonic and magnetic properties could lead to unique optical switchable magnetic devices and sensors. In this work, a multiphase TiN-Au-Ni nanocomposite system with core–shell-like Au-Ni nanopillars embedded in a TiN matrix has been demonstrated on flexible mica substrates. The three-phase nanocomposite film has been compared with its single metal nanocomposite counterparts, i.e., TiN-Au and TiN-Ni. Magnetic measurement results suggest that both TiN-Au-Ni/mica and TiN-Ni/mica present room-temperature ferromagnetic property. Tunable plasmonic property has been achieved by varying the metallic component of the nanocomposite films. The cyclic bending test was performed to verify the property reliability of the flexible nanocomposite thin films upon bending. This work opens a new path for integrating complex nitride-based nanocomposite designs on mica towards multifunctional flexible nanodevice applications.
