The dependence of Mo ratio on the formation of uniform black silicon by helium plasma irradiation

Abstract

Reducing the optical reflection of silicon (Si) material is a crucial issue on the surface of solar cells and other photonic applications. Fabrication of nanocone structures on the Si surface (black Si) by plasma (helium or argon) irradiation is a novel technique in recent decades with advantages, such as simple, economical, and harmless to the Si substrate. However, the uniformity and controllability of the surface remain problematic. In this study, uniform black silicon was obtained by low energy (<50 eV) helium ion irradiation with auxiliary Mo co-deposition. The characteristics of the nanocone show a clear relation with the Mo ratio. Deposited Mo was found to accumulate on the cone body, especially on the tip, and it worked as a nano mask to induce the formation of the nanocone and protect it from sputtering. The surface with high and large diameter nanocones possesses low reflectances of roughly 2%. The study of the relation between Mo ratio, characteristics of the nanostructure, and the reflectance of the surface raises a potential method of surface tailoring.

Structural Correlation of Random Lasing Performance in Plasma-Induced Surface-Modified Gallium Nitride

“…Samples were fixed with two Mo screws and a cover with a 9 × 9 mm 2 window. The Mo screws can be considered as one of the impurity sources, which plays an important role in the formation of the nanostructures, similar to that in the previous study . The sputtering rate of Mo is smaller than that of GaN in Ar plasma, which allows aggregated Mo acting as masks of GaN during the plasma irradiation.…”

“…The Mo screws can be considered as one of the impurity sources, which plays an important role in the formation of the nanostructures, similar to that in the previous study. 17 The sputtering rate of Mo is smaller than that of GaN in Ar plasma, which allows aggregated Mo acting as masks of GaN during the plasma irradiation. In addition, a Mo sputtering wire can be installed 10 mm in front of the substrate to independently control the deposition of Mo by applying a DC bias of V SW = −50 V. The background pressure and the Ar gas pressure in the chamber were 5 × 10 −5 Pa and 1.0 Pa, respectively.…”

“…In the experiment, Mg-doped (p-type) GaN templates (4.5 μm thick on sapphire substrates, MTK Co., Ltd.) were irradiated with magnetically confined argon (Ar) plasma in the linear plasma device, Co-NAGDIS, , as shown in Figure (a). Samples were fixed with two Mo screws and a cover with a 9 × 9 mm 2 window.…”

“…In our previous study, random conical structures were formed on Si by plasma etching of a Si substrate with codeposition of a small amount of Mo impurity, termed CoDE (Co-deposition Etching) . CoDE processing simultaneously performs plasma etching and impurity deposition where the etching and deposition rates can be controlled independently.…”

Increased Photoelectrochemical Performance of Vanadium Oxide Thin Film by Helium Plasma Treatment with Auxiliary Molybdenum Deposition

“…It has a potential to control surface morphology, form composite, and induce vacancies in a one‐step process of He plasma irradiation. In the future, an additional sputtering source to control the deposition rate of Mo will be introduced, such as demonstrated previously, [ 70 ] it will be a versatile method with a better controllability.…”