Zn_xSb_100−x films with low Zn content are crystallized in a single-step process with Sb, while the film (Zn/Sb ratio is about 1 : 1) exhibits a two-step crystallization process with ZnSb metastable and stable phases. Importantly, ZnSb films have higher crystallization temperature (~257 °C), larger crystalline activation energy (~5.63 eV), better 10 year-data-retention (~201 °C) and lower melting temperature (~500 °C).

Surface-enhanced Raman scattering (SERS) spectroscopy has been developed into a cross-disciplinary analytical technology through exploring various materials’ Raman vibrational modes with ultra-high sensitivity and specificity. Although conventional noble-metal based SERS substrates have achieved great success, oxide-semiconductor-based SERS substrates are attracting researchers’ intensive interest due to their merits of facile fabrication, high uniformity and tunable SERS characteristics. Among all the SERS active oxide semiconductors, molybdenum oxides (MoO_x) possess exceptional advantages of high Raman enhancement factor, environmental stability, recyclable detection, etc. More interestingly, the SERS effect of the MoO_x SERS substrates may involve both the electromagnetic enhancement mechanism and the chemical enhancement mechanism, which is determined by the stoichiometry and morphology of the material. Therefore, the focus of this review will be on two critical points: (1) synthesis and material engineering methods of the functional MoO_x material and (2) MoO_x SERS mechanism and performance evaluation. First, we review recent works on the MoO_x preparation and material property tuning approaches. Second, the SERS mechanism and performance of various MoO_x substrates are surveyed. In particular, the performance uniformity, enhancement factor and recyclability are evaluated. In the end, we discuss several challenges and open questions related to further promoting the MoO_x as the SERS substrate for monitoring extremely low trace molecules and the theory for better understanding of the SERS enhancement mechanism.

Due to the intrinsic contradiction of electrical conductivity and Seebeck coefficient in thermoelectric materials, the enhancement for the power factor (PF) is limited. Since the PF decides the output power, strategies to the enhancement of PF are of paramount importance. In this work, Bi₂Te₃/Sb and Bi₂Te₃/W multilayer films are proposed to enhance the thermoelectric properties. Both systems possess extremely high conductivity of ≈5.6 × 10⁵ S m⁻¹. Moreover, the electrical conductivity and Seebeck coefficient simultaneously increase as temperature rising, showing the overcome of the intrinsic contradiction. This results in ultrahigh PFs of 1785 µWm⁻¹ K⁻² for Bi₂Te₃/W and of 1566 µWm⁻¹ K⁻² for Bi₂Te₃/Sb at 600 K. Thermal heating of the Bi₂Te₃/Sb multilayer system shows compositional changes with subsequent formation of Bi‐Te‐Sb phases, Sb‐rich Bi‐Te precipitates, and cavities. Contrary, the multilayer structure of the Bi₂Te₃/W films is maintained, while Bi₂Te₃ grains of high‐crystalline quality are confined between the W layers. In addition, bilayer defects in Bi₂Te₃ and smaller cavities at the interface to W layers are also observed. Thus, compositional and confinement effects as well as structural defects result in the ultrahigh PF. Overall, this work demonstrates the strategies on how to obtain ultrahigh PFs of commercial Bi₂Te₃ material by microstructure engineering using multilayer structures.