Effect of oxygen flow on the optical properties of hafnium oxide thin films by dual-ion beam sputtering deposition

Controlling the optical properties of hafnium dioxide thin films deposited with electron cyclotron resonance ion beam deposition

“…Hafnium oxide, also known as Hafnia (HfO 2 ), is one of the most attractive high refractive index materials, high-k dielectric, with excellent thermal and chemical stability [1] that are widely used in optical coating applications. They are also commonly used in multilayer optical coatings as the high index material, alongside low index material like silica, where it can be utilized in interference filters, anti-reflective coatings, metal-oxide-semiconductor transistors, and cameras that can be utilized for space applications [2][3][4]. Other applications that HfO 2 films has been utilized aside for optical coatings are memory applications [1,5,6], ferroelectrics transistors which can be used for in-memory computing devices, as well as neuromorphic devices [7][8][9] and as HfO 2 based nanoagent in clinical trials for radiosensitized tumor therapy [10].…”

“…These HfO 2 coated optics are utilize in filters or mirrors for laser spectroscopy, laser diodes, and multilayer high reflection mirrors for Gravitational-wave interferometers, for example [13][14][15]. Although, from previous studies by many authors over the years, it shows that HfO 2 has its favorable and advantages characteristics for different applications, but the optical and structural properties of the thin films can vary depending on the deposition methods, as well as the deposition parameters [1,2]. This leads to common deposition techniques, including electron beam evaporation [11,16,17], dual ion beam sputtering [18,19], reactive low voltage ion plating, radio frequency (RF) magnetron sputtering [20], high pressure reactive sputtering [21], pulsed laser deposition [1], and ion beam deposition (IBD) [22,23], yielding inconsistent optical, electronic and structural properties.…”