Relative oxidation state of the target as guideline for depositing optical quality RF reactive magnetron sputtered Al<sub>2</sub>O<sub>3</sub> layers
Carlijn I. van Emmerik, Ward Hendriks, Martijn M. Stok, Michiel de Goede, Lantian Chang, Meindert Dijkstra, F. B. Segerink, Dominic Post, Enrico G. Keim, Mike J. Dikkers, Sonia M. García‐Blanco
Abstract
Amorphous Al 2 O 3 is an attractive material for integrated photonics. Its low losses from the UV till the mid-IR together with the possibility of doping with different rare-earth ions permits the realization of active and passive functionalities in the same chip at the wafer level. In this work, the influence of reactive gas flow during deposition on the optical (i.e., refractive index and propagation losses) and material (i.e., structure of the layer) characteristics of the RF reactive sputtered Al 2 O 3 layers is investigated and a method based on the oxidation state of the sputtering target is proposed to reproducibly achieve low loss optical guiding layers despite the continuous variation of the condition of the target along its lifetime.