arXiv subjects

Jiangjing Wang

Publications and source records attributed to Jiangjing Wang.

3 recordsLinked to original sources

arXiv2026

Effects of thermal annealing and film thickness on the structural and optical properties of indium-tin-oxide thin films

Indium-tin oxide (ITO) is a crucial functional layer for the optoelectronic applications, such as non-volatile color display thin films based on the ITO/phase-change material (PCM)/ITO/reflective metal multilayer structures on a silicon substrate. In addition to non-volatile color tuning by PCMs, thermally induced crystallization may alter the optical properties of ITO layers as well. But the potential change in color of the ITO layers is not considered so far. In this work, we investigate the structural and optical properties of ITO thin films via X-ray diffraction, spectroscopic ellipsometry and ultraviolet-visible spectrophotometry measurements. After thermal annealing at 250 °C, the ITO thin films of 15-100 nm get crystallized with strong changes in refractive index n and extinction coefficient k in the visible light range. However, for the 5-nm ITO thin film, crystallization is only observed after thermal annealing at 350 °C and the change in color is limited upon phase transition. We provide a colormap of the ITO/platinum/silicon structure in terms of the annealing temperature (150-350 °C) and ITO film thickness (5-100 nm). Our work suggests that the intrinsic change in colors of ITO layers should also be considered for the PCM-based reconfigurable display application.

physics.optics↗

arXiv2025

Isothermal Annealing Effects on $β$-Relaxations and Crystallization Behaviors in Amorphous GeTe

A secondary $β$-relaxation process is often the dominant source of atomic dynamics below $T_\mathrm{g}$ in many glass forming systems. Recent studies reported the presence of $β$-relaxations in amorphous phase-change materials (PCMs) and showed that suppressing the $β$-relaxation via annealing in Ge$_{15}$Sb$_{85}$ can effectively slow down its crystallization kinetics. Yet, when Sb is replaced by Te, similar annealing protocol has little effect on the Te-rich alloy Ge$_{15}$Te$_{85}$. Here, we investigate amorphous GeTe that is a Sb-free PCM, but with faster crystallization kinetics than Ge$_{15}$Te$_{85}$. Using powder mechanical dynamic spectroscopy, we observe a clear reduction of the excess-wing in the loss modulus upon isothermal annealing, indicating a suppression of its $β$-relaxation. Ultrafast calorimetric analysis and time-resolved optical reflectivity measurements show that, whereas as-deposited GeTe exhibit stochastic crystallization behaviors, annealed samples crystallize more slowly with reduced stochasticity. Synchrotron X-ray scattering experiments reveal reinforced Peierls-like distortions in the amorphous structure after annealing, and demonstrate that, even if annealing introduces nucleation sites, it nonetheless slows down crystallization kinetics. These finding suggests that, in annealed GeTe, crystallization is limited by crystal growth rate, which is retarded through the suppression of $β$-relaxation.

cond-mat.mtrl-sci↗

arXiv2025

Spin glass behavior in amorphous CrSiTe3 alloy

Owing to the intrinsically high crystallization temperatures, layered phase-change materials, such as CrGeTe3 and InGeTe3, are attracting attention for embedded memory applications, In addition to the electrical contrast, a major change in magnetic properties is observed in CrGeTe3 upon switching from the crystalline to the amorphous state. In this work, we report a combined ab initio modeling and magnetic characterization study on the isostructural silicon parent compound of CrGeTe3, namely, CrSiTe3. Amorphous CrSiTe3 has similar structural properties to amorphous CrGeTe3; however, it shows a smaller energy difference between the ferromagnetic configuration and the random magnetic configuration, indicating a high probability of spin glass formation. Indeed, direct-current and alternating-current magnetic measurements show that the coercive force of amorphous CrSiTe3 is higher than that of amorphous CrGeTe3. Therefore, the pinning effect of spins is enhanced in amorphous CrSiTe3, leading to a more robust spin glass state with a higher freezing temperature. The large magnetic contrast between the amorphous and crystalline phase could make CrSiTe3 a potential candidate for phase-change magnetic switching applications.

cond-mat.mtrl-sci↗