Al:ZnO as a platform for near-zero-index photonics: enhancing the doping efficiency of atomic layer deposition
Fabrication of materials with predefined physical properties is in demand in many areas of physics. In this work, researchers from the US have explored the multi-dimensional fabrication space and produced thin films of Aluminium doped ZnO with electric properties that were not achievable before. This transparent conducting oxide has a range of applications in many current devices and the list of these applications will be further extended by the use of the so-called near-zero index regimes for making functional metasurfaces. By modifying the fabrication process (atomic layer deposition) and adjusting some of the parameters to the values that are typically not accessible, they achieved record high doping efficiencies with more unified distribution of dopants. This allows to substantially increase the frequency range in which the materials can access zero refractive index. The proposed strategies for improved fabrication can potentially be useful in processing of other materials.