Optical and structural characterization of Ge clusters embedded in ZrO2

Abstract

The change of optical and structural properties of Ge nanoclusters in ZrO 2 matrix have been investigated by spectroscopic ellipsometry versus annealing temperatures. Radio-frequency top-down magnetron sputtering approach was used to produce the samples of different types, i.e. single-layers of pure Ge, pure ZrO 2 and Ge-rich-ZrO 2 as well as multi-layers stacked of 40 periods of 5-nm-Ge-rich-ZrO 2 layers alternated by 5-nm-ZrO 2 ones. Germanium nanoclusters in ZrO 2 host were formed by rapid-thermal annealing at 600-800 • C during 30 s in nitrogen atmosphere. Reference optical properties for pure ZrO 2 and pure Ge have been extracted using single-layer samples. Asdeposited multi-layer structures can be perfectly modeled using the effective medium theory. However, annealed multi-layers demonstrated a significant diffusion of elements that was confirmed by medium energy ion scattering measurements. This fact prevents fitting of such annealed structure either by homogeneous or by periodic multi-layer models.

A Review on Ge Nanocrystals Embedded in SiO2 and High‐k Dielectrics

“…Ge‐rich ZrO 2 films (GeZrO x ) were deposited by MS and Ge ion implantation . Thin ZrO 2 films crystallize at higher temperatures than thin films of Ge .…”

“…The ZrO 2 is an effective barrier against Ge diffusion (e.g., better than Al 2 O 3 ) . Therefore, the synthesis of size and position controlled Ge nanocrystals is possible by using superlattice structures …”

Ge nanoparticles in SiO2 for near infrared photodetectors with high performance

“…For example, the temperature necessary for Ge-NPs formation is influenced by the host matrix and if the annealing is performed in a furnace or in a rapid thermal processor. So, Ge-NPs are formed at about 310 °C 30 in indium tin oxide (ITO), in the range of 800–1000 °C 31,32 in Al 2 O 3 or above 700 °C in ZrO 2 matrices 33 . Structures based on Ge-NPs deposited on glass or flexible substrates can be obtained using or not a thermal treatment during the deposition process 34–36 .…”

In-Situ Control of Defect Dynamics By Ellipsometry During Ion Implantation – Evolution of Disorder and Cavity Structure in Single-Crystalline Ge During Implantation of Sb Ions

“…Ge and its alloys (primarily with Si) are also used as Bragg re ectors 3 , photodiodes 2 , materials of controlled optical properties (especially in the infrared wavelength range) 4 , as well as in band gap 5 and refractive index 6 engineering. Although the size-dependent optical properties of Ge were measured earlier 7 than those of Si 8 , the attention of researchers has turned only recently to Ge nanocrystals 9,10 (NCs). Some remarkable features of Ge, including the wide tunable spectral range, stronger quantum con nement (QC) effects, compound applications 11,12 , biocompatibility, and electrochemical stability looked very attractive.…”

“…for 50-300-keV self-ion bombardment 22 . Structural properties such as the size of crystals or the degree of amorphization can also be determined by optical methods 6,7,9,23 . Rutherford backscattering spectrometry (RBS) allows to reveal the degree of crystallinity, crystal structure (when combined with channeling) and the depth distribution of elements.…”