Sacrificial‐Layer Atomic Layer Deposition for Fabrication of Non‐Close‐Packed Inverse‐Opal Photonic Crystals

Abstract

A method is presented for predicting and precisely controlling the structure of photonic crystals fabricated using sacrificial‐layer atomic layer deposition. This technique provides a reliable method for fabrication of high‐quality non‐close‐packed inverse shell opals with large static tunability and precise structural control. By using a sacrificial layer during opal infiltration, the inverse‐opal pore size can be increased with sub‐nanometer resolution and without distorting the lattice to allow for a high degree of dielectric backfilling and increased optical tunability. For a 10 % sacrificial layer, static tunability of 80 % is predicted for the inverse opal. To illustrate this technique, SiO2 opal templates were infiltrated using atomic layer deposition of ZnS, Al2O3, and TiO2. Experimentally, a static tunability of over 600 nm, or 58 %, was achieved and is well described by both a geometrical model and a numerical‐simulation algorithm. When extended to materials of higher refractive index, this method will allow the facile fabrication of 3D photonic crystals with optimized photonic bandgaps.

Reinforcing nanocolloidal crystals by tuning interparticle bonding via atomic layer deposition

“…Unlike CVD, ALD is self-limiting by keeping the precursors separate, enabling ultrahigh-precision control over the deposition and providing superior film conformity and uniformity even for complex structures with ultrahigh aspect ratios [15][16][17][18][19]. Thus, ALD has been used as a way of infiltrating NCC templates to generate inverse opals [19][20][21][22][23][24][25][26]. Our previous studies [27,28] demonstrated that ALD can be used to significantly reinforce films composed of randomly packed polydisperse nanoparticles.…”

Photonic band gaps in non-close-packed inverse opals

“…2 indicates. Finally, this backbone template can be further modified by conformally coating dielectric layers onto its interior, as reported by Míguez et al, King et al,and Graugnard et al,31,45,46 and shown in Fig. 2͑e͒.…”

“…46 With this technique, structural modifications to the original template and inverse shell opal backbone can be made with precise and independent control of the tube and sphere radii, adding additional geometrical flexibility and PBG adjustment. In this technique ͑Fig.…”

Photonic band tuning in 2D photonic crystals by atomic layer deposition

“…With ALD, highly conformal films can be grown with a precision of 0.05 nm, which, when combined with the availability of a wide range of low temperature film growth protocols, enables a high degree of control over material and structural properties to precisely tune optical properties [3]. Two-dimensional photonic crystals have been developed extensively for applications in optical interconnects, beam steering, and sensor devices; and are predominantly fabricated by electron-beam lithography.…”