Structural and optical properties of yttrium oxide thin films for planar waveguiding applications

Abstract

Thin films of yttrium oxide, Y2O3, were deposited by reactive sputtering and reactive evaporation to determine their suitability as a host for a rare earth doped planar waveguide upconversion laser. The optical properties, structure, and crystalline phase of the films were found to be dependent on the deposition method and process parameters. X-ray diffraction analysis on the “as-deposited” thin films revealed that the films vary from amorphous to highly crystalline with a small broad peak at 29° corresponding to the ⟨222⟩ reflections of Y2O3. The samples with the polycrystalline structure had a stoichiometry close to bulk cubic Y2O3. Scanning electron microscopy imaging revealed a regular column structure confirming their crystalline nature. The thin film layers which allowed guiding in both visible and infrared regions had lower refractive indices, higher oxygen content, and a more amorphous structure. Higher oxygen pressures during the deposition lead to a more amorphous layer.

Study on Structural and Thermal Characteristics of Heteroleptic Yttrium Complexes as Potential Precursors for Vapor Phase Deposition

“…Especially, due to their large band gap (5.5 eV) and high refractive index (ca. 2.0), yttrium oxide (Y 2 O 3 ) and rare‐earth (RE) doped Y 2 O 3 like Ce 3+ :Y 2 O 3 or Nd 3+ :Y 2 O 3 exhibit outstanding potential in the field of optics such as lasers, planar waveguides or antireflective coatings . Moreover, the high relative permittivity of Y 2 O 3 (ε r ca.…”

Electronic Structure and Optical Quality of Nanocrystalline Y2O3 Film Surfaces and Interfaces on Silicon

“…Oxide dielectrics have been the subject of numerous investigations for many years due to their possible device integration in a wide range of technologies involving electronics, electro-optics, optoelectronics, and magneto-electronics. − Yttrium oxide (Y 2 O 3 ), a stable oxide of yttrium metal, has received significant attention in recent years in view of its possible integration into a wide range of scientific and technological applications. − Y 2 O 3 films exhibit excellent electronic properties such as transparency over a broad spectral range (0.2–8 μm), high dielectric constant (∼14–18), high refractive index (∼2), large band gap (∼5.8 eV), low absorption (from near-UV to IR), and superior electrical breakdown strength (>3 MV/cm). ,− ,− These properties make Y 2 O 3 films interesting for various electrical and optical devices. − Yttrium oxides were proposed as hosts for rare-earth elements, and efficient thin film phosphors were prepared. − The interface layer formation, however, was detected for several compounds, and structural and chemical parameters of the interface were dependent on the deposition conditions. Therefore, controlled growth and manipulation of microstructure, particularly at the nanoscale dimensions, has important implications for the design and applications of Y 2 O 3 films.…”

Study on reactive sputtering of yttrium oxide: Process and thin film properties

“…Briefly, owing to high chemical and thermal stability (melting point is up to~2349°C) [1,2], and its mechanical properties (high strength and fracture toughness) [3], yttrium oxide films and particles have been used in thermal or reaction barrier coatings [4] and oxide dispersion strengthened steels [5,6]. Particularly, due to the excellent optical and electric properties, including a wide transmittance range, high refractive index (~2), low absorption, large band gap (~5.4 eV), and high permittivity (~14-18) accompanied with a lattice match with Si and GaAs (for the cubic phase) and graphene (for the hexagonal phase), yttrium oxide thin films become one of the most interesting materials widely used in optical waveguides [7][8][9], and as an antireflective layer [10], or as a high efficiency phosphor by doping with other rare-earth elements [11,12], as well as one component of high-quality metal-oxide-semiconductor (MOS) based devices [13][14][15][16][17][18].…”