Crystallization and inter-diffusional behaviors in the formation of VO2(B) thin film with layered W-doping

Abstract

To achieve a better material for uncooled infrared (IR) detector, polycrystalline VO 2 (B) thin films with layered W-doping were fabricated on Si substrates by magnetron sputtering, and the best temperature coefficient of resistance (TCR) value reached 4.1%/K. The film synthesis was in a two-step route, first deposition at room temperature and then post-deposition annealing at 450 ℃, to better control the crystallization behavior. Various transmission electron microscopy (TEM) methods were employed to investigate three sets of multi-layered films with different deposition time, 10, 20, and 30 min, with especial emphasis on the effect of layered W-doping scheme on the formation of multiple VO 2 (B) layers. Spatial-resolved energy dispersive X-ray spectroscopy (EDS) revealed the alternative patterns of W-rich layers and W-poor layers, while the thinner films exhibited better crystallinity and texturing. By comparison with an as-deposited film, it was found that the inter-diffusion between the two types of layers was completed in the deposition step while both remained in amorphous structure. A stable W solution of about 8 cat% in VO 2 (B) layers measured from all these films indicated that the layered doping can tailor the multi-layered microstructure to optimize the performance of VO 2 (B) films.

Element doping: a marvelous strategy for pioneering the smart applications of VO2

“…234 It is reported that the alternate patterns of W-rich layers and W-poor layers enhance the TCR of VO 2 -based films. 235 Other than tungsten, Ti, 118 Nb, 107,118 Cr, 236 Al, 237 and Ta 237 are also reported to reduce the resistivity of VO 2 while maintaining an acceptable TCR (>10% per K). In particular, the 9% Ti-doped VO 2 and 1.8% Nb-doped VO 2 show a high TCR value of 24.8% per °C and 21.6% per °C, respectively.…”

Electric Modulation of Conduction in MAPbBr3 Single Crystals

“…In this work, MAPbBr3 single crystal was chose for the conduction study, because MAPbBr3 is non-polar (centrosymmetric) [18] and therefore ferroelectricity could be excluded, while the influence of grain boundaries can also be ignored. Compared with polycrystalline thin films [19,20], MAPbX3 single crystals present lower trap density and much better environmental stability, which can be considered as an ideal platform for investigating their intrinsic physical properties. The electric-field-driven resistance switching accompany by a diode-like behavior was produced in the Au/MAPbBr3/Au structure.…”

Tuning Nucleation Sites to Enable Monolayer Perovskite Films for Highly Efficient Perovskite Solar Cells

“…In addition, by manipulating the competition between nucleation and growth [27] and by restraining the overgrowth of localized crystals [28], the coverage ratio of the perovskite film could be improved. In all, it is important to effectively control and optimize the coverage ratio of the perovskite film through the guidance of crystallization crystallography, which has been widely proved to be an efficient way of manipulating the microstructures of crystals [29][30][31][32].…”