Zhongzhen Wu

Evaporative Self-Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays.

Millimeter-scale 3D superlattice arrays composed of dense, regular, and vertically aligned gold nanorods are fabricated by evaporative self-assembly. The regular organization of the gold nanorods into a macroscopic superlattice enables the production of a plasmonic substrate with excellent sensitivity and reproducibility, as well as reliability in surface-enhanced Raman scattering. The work bridges the gap between nanoscale materials and macroscopic applications.

Novel plasma immersion ion implantation and deposition hardware and technique based on high power pulsed magnetron discharge

A novel plasma immersion ion implantation technique based on high power pulsed magnetron sputtering (HPPMS) discharge that can produce a high density metal plasma is described. The metal plasma is clean and does not suffer from contamination from macroparticles, and the process can be readily scaled up for industrial production. The hardware, working principle, and operation modes are described. A matching circuit is developed to modulate the high-voltage and HPPMS pulses to enable operation under different modes such as simultaneous implantation and deposition, pure implantation, and selective implantation. To demonstrate the efficacy of the system and technique, CrN films with a smooth and dense surface without macroparticles were produced. An excellent adhesion with a critical load of 59.9 N is achieved for the pure implantation mode.

Discharge current modes of high power impulse magnetron sputtering

Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

Origin of Initial Current Peak in High Power Impulse Magnetron Sputtering and Verification by Non-Sputtering Discharge*

A non-sputtering discharge is utilized to verify the effect of replacement of gas ions by metallic ions and consequent decrease in the secondary electron emission coefficient in the discharge current curves in high-power impulse magnetron sputtering (HiPIMS). In the non-sputtering discharge involving hydrogen, replacement of ions is avoided while the rarefaction still contributes. The initial peak and ensuing decay disappear and all the discharge current curves show a similar feature as the HiPIMS discharge of materials with low sputtering yields such as carbon. The results demonstrate the key effect of ion replacement during sputtering.

Gold Nanorods: Evaporative Self‐Assembly of Gold Nanorods into Macroscopic 3D Plasmonic Superlattice Arrays (Adv. Mater. 13/2016)

On page 2511, X.-F. Yu, P. K. Chu, and co-workers demonstrate the successful fabrication of millimeter-scale three-dimensional superlattice arrays consisting of dense, regular, and vertically aligned gold nanorods by the evaporative self-assembly method. The excellent performance in surface-enhanced Raman scattering indicates applications in plasmonic substrates.