Surface-Nanostructured Al–AlN Composite Thin Films with Excellent Broad-Band Antireflection Properties Fabricated by Limited Reactive Sputtering

Abstract

Al−AlN composite thin films with surface nanostructures possessing excellent broad-band antireflection properties can be simply fabricated by using a simple sputtering-based method, namely, limited reactive sputtering at elevated temperature. A mixture of Ar and N 2 gases with limited gas flow of N 2 is used. During the process, the limited amount of the N ions and radicals can only consume some of the sputtered Al atoms for the formation of AlN, so that the Al−AlN composite thin film can finally be deposited on the substrate. Compared to the traditional cosputtering for composite deposition, which works necessarily with two or more targets simultaneously, here only a single Al target is required. When the substrate temperature is higher than 100 °C, surface nanostructures can be evolved because of the different diffusion kinetics of Al and AlN. The total reflection was reduced drastically (<10%) in the spectral range 300−2000 nm. The Al−AlN composite thin films exhibit also a good electric conductivity.

Magnetron Sputtered AlN Layers on LTCC Multilayer and Silicon Substrates

“…An aluminum excess significantly affects refractive index and extinction coefficient. Accordingly, aluminum rich AlN can be used as absorbance layer in optical applications [2,41]. hexagonal inclusions.…”

Characterization of Structure, Morphology, Optical and Electrical Properties of AlN–Al–V Multilayer Thin Films Fabricated by Reactive DC Magnetron Sputtering

“…In this regard, an aluminum layer oriented to the (111) surface by planes ((111) Al) may be of interest as a lower electrode layer for AlN. In spite of the fact that available literature contains some information on Al-AlN films [24,26,[28][29][30][31][32][33], understanding the influence of the parameters of the magnetron sputtering technique is relatively incomplete. The situation is complicated by the fact that there are several different variants of the magnetron sputtering technique, e.g., radio frequency (RF) and direct current (DC) magnetron sputtering, with different features.…”

“…The AlN layers in such films were amorphous. In the article [31], the effect of temperature on the state of the deposited layer during reactive magnetron sputtering at direct current was considered, where an increase in the crystallinity of the Al and AlN phases with an increase in the substrate temperature to 400 • C was noted. However, in this work, a single two-phase composite AlN-Al layer was created, not a multilayer structure.…”

Self-Rolled-Up Aluminum Nitride-Based 3D Architectures Enabled by Record-High Differential Stress

“…Among these techniques, RF magnetron reactive sputtering has been established as a leading technology to achieve high-quality AlN thin films with excellent surface morphology. Highly c -axis-oriented AlN films with precise control of residual stresses can be deposited at temperatures not exceeding 350 °C, making the process complementary metal-oxide-semiconductor (CMOS)-compatible. , However, controlling the residual stress, especially tensile stress, for very thin AlN films (thinner than ∼100 nm) by this method is still challenging. Compared with other 3D-patterned structures, S-RuMs provide several advantages in terms of reduced footprint and hybrid functionalization that allow the on-chip fabrication of complex 3D architectures using conventional planar processing techniques.…”