Morphological and Surface-State Challenges in Ge Nanoparticle Applications

Synthesis of Silicon and Germanium Oxide Nanostructures via Photonic Curing; a Facile Approach to Scale Up Fabrication

Silicon and Germanium oxide (SiOx and GeOx) nanostructures are promising materials for energy storage applications due to their potentially high energy density, large lithiation capacity (~10X carbon), low toxicity, low cost, and high thermal stability. This work reports a unique approach to achieving controlled synthesis of SiOx and GeOx nanostructures via photonic curing. Unlike conventional methods like rapid thermal annealing, quenching during pulsed photonic curing occurs rapidly (sub-millisecond), allowing the trapping of metastable states to form unique phases and nanostructures. We explored the possible underlying mechanism of photonic curing by incorporating laws of photophysics, photochemistry, and simulated temperature profile of thin film. The results show that photonic curing of spray coated 0.1 M molarity Si and Ge Acetyl Acetate precursor solution, at total fluence 80 J cm-2 can yield GeOx and SiOx nanostructures. The as-synthesized nanostructures are ester functionalized due to photoinitiated chemical reactions in thin film during photonic curing. Results also showed that nanoparticle size changes from ~48 nm to ~11 nm if overall fluence is increased by increasing the number of pulses. These results are an important contribution towards large-scale synthesis of the Ge and Si oxide nanostructured materials which is necessary for next-generation energy storage devices.

A novel bimetallic MXene derivative QD-based ECL sensor for miRNA-27a-3p detection

In this work, a novel ECL biosensor has been developed based on bimetallic MXene derivative QDs (Mo₂TiC₂ QDs) and SnS₂ nanosheets/lipid bilayer to detect the gastric cancer marker miRNA-27a-3p. On the one hand, the inter-band excitation of Mo₂TiC₂ QDs can inject the additional carriers, which were less suppressed by boundary effects and made a significant contribution to the luminescence process. Semiconductor Mo₂TiC₂ further inhibited the formation of internal electric field and potential oxidation. Therefore, Mo₂TiC₂ QDs processed superior luminous intensity and better stability. On the other hand, SnS₂ nanosheets coated with phospholipid bilayer were designed as sensing interface. SnS₂ nanosheets not only enhanced the luminous intensity of Mo₂TiC₂ QDs by virtue of their large surface area and low dielectric constant, but also improved the stability of lipid bilayer. Due to the excellent properties and synergy work of Mo₂TiC₂ QDs and the lipid bilayer-modified SnS₂ nanosheets, the sensing system displayed high sensitivity and good reproducibility in the analysis application. As a result, the biosensor displayed good linear correlation between the ECL intensity and the concentration of miRNA-27a-3p over a wide range from 1 fM to 10 nM with the detection limit as low as 1 fM. The sensing system including the joint contribution of Mo₂TiC₂ QDs, SnS₂ nanosheets and lipid bilayers had great potential for clinical applications.

P-Type 2D Semiconductors for Future Electronics

2D semiconductors represent one of the best candidates to extend Moore's law for their superiorities, such as keeping high carrier mobility and remarkable gate-control capability at atomic thickness. Complementary transistors and van der Waals junctions are critical in realizing 2D semiconductors-based integrated circuits suitable for future electronics. N-type 2D semiconductors have been reported predominantly for the strong electron doping caused by interfacial charge impurities and internal structural defects. By contrast, superior and reliable p-type 2D semiconductors with holes as majority carriers are still scarce. Not only that, but some critical issues have not been adequately addressed, including their controlled synthesis in wafer size and high quality, defect and carrier modulation, optimization of interface and contact, and application in high-speed and low-power integrated devices. Here the material toolkit, synthesis strategies, device basics, and digital electronics closely related to p-type 2D semiconductors are reviewed. Their opportunities, challenges, and prospects for future electronic applications are also discussed, which would be promising or even shining in the post-Moore era.

Self-Limiting Synthesis of Ultrathin Ge(110) Single Crystal via Liquid Metal

Germanium, the prime applied semiconductor, is widely used in solid-state electronics and photoelectronics. Unfortunately, since the 3D diamond-like structure with strong covalent bonds impedes the 2D anisotropic growth, only the examples of ultrathin Ge along the (111) plane have been investigated, much less to the controllable synthesis along another crystal surface. Meanwhile, Ge(111) flakes are limited in semiconductor applications because of their gapless property. Here, ultrathin Ge(110) single crystal is synthesized with semiconductive property via gallium-associated self-limiting growth. The obtained ultrathin Ge(110) single crystal exhibits anisotropic honeycomb structure, uniformly incremental lattice, wide tunable direct-bandgap, blue-shifted photoluminescence emission, and unique phonon modes, which are consistent with the previous theoretical predictions. It also confirms excellent second harmonic generation and high hole mobility of 724 cm² V^-1 s^-1 . The realization of ultrathin Ge(110) single crystal will provide an excellent candidate for application in electronics and optoelectronics.

Synthesis of Ge1−xSnx nanoparticles under non-inert conditions

Ge1−xSnx nanoparticles are interesting for many different optoelectronic devices, however, the synthesis normally involves highly inert conditions, making it less promising for industry implementation. Here, a new non-inert synthesis is presented.

Recent developments in germanium containing clusters in intermetallics and nanocrystals

Multimetallic clusters can be described as building blocks in intermetallics, compounds prepared from all metals and/or semi-metals, and in Zintl phases, a subset of intermetallics containing metals with large differences in electronegativity. In many cases, these intermetallic and Zintl phases provide the first clue for the possibilities of bond formation between metals and semi-metals. Recent advances in multimetallic clusters found in Zintl phases and nanoparticles focusing on Ge with transition metals and semi-metals is presented. Colloidal routes to Ge nanocrystals provide an opportunity for kinetically stabilized Ge-metal and Ge-semi-metal bonding. These routes provide crystalline nanoclusters of Ge, hereafter referred to as nanocrystals, that can be structurally characterized. Compositions of Ge nanocrystals containing transition metals, and the semi-metals, Sb, Bi, and Sn, whose structures have recently been elucidated through EXAFS, will be presented along with potential applications.