Crystallization of HfO2 thin films and their influence on laser induced damage

Zoltán Balogh-Michels,Antonia Neels,Daniel Schachtler,Thomas Gischkat,Alexander Stuck,Roelene Botha,Andreas Bächli,Igor Stevanovic,Ruggero Frison,H Michinel,M.F Costa,O Frazao

doi:10.1051/epjconf/202023812004

Abstract

We present our investigation on the crystallization of IBS HfO2 on (0001) SiO2. The crystallization was studied by in-situ XRD. The activation energy was 2.6±0.5 eV. The growth follows a two-dimensional mode. LIDT measurements (5000-on-1) with 10 ns pulses at 355 nm on 3QWT HfO2 layers shows that the crystallization leads to increase of the laser irradiation resistance. The 0%-LIDT of the as coated sample was 3.1 J/cm2 and increased to 3.7 J/cm2 after 5h @ 500°C.

Highlights

Thin-film interference coatings, like antireflection or high reflectance coatings as well as wavelength and polarization selective coatings, are key elements of optical components as they allow to tune or even radically alter their optical properties [1,2]
Current high-end optical coatings in the VIS/NIR range are mainly based on ion beam sputtered (IBS) multilayers
Thermal annealing of a single layer or multilayer stacks is a well-established way to improve the properties like optical losses or laser irradiation resistance [3]

Summary

Introduction

Thin-film interference coatings, like antireflection or high reflectance coatings as well as wavelength and polarization selective coatings, are key elements of optical components as they allow to tune or even radically alter their optical properties [1,2]. Thermal annealing of a single layer or multilayer stacks is a well-established way to improve the properties like optical losses or laser irradiation resistance [3]. The understanding of the crystallization process, the dependence on time and temperature and the activation energy are essential for defined controlling the thermal treatment and tuning the properties. Investigations show that high temperature annealing leads to the crystallization and the laserinduced damage behaviour improves [4]. Investigate the crystallization of thin HfO2 films by means of in-situ x-ray diffractometry and its effect on the laserinduced damage threshold

Crystallization

Laser damage testing

Conclusions