Size- and position-controlled Ge nanocrystals separated by high-k dielectrics

Abstract

Germanium nanocrystals embedded in high-k dielectric matrices are of main interest for infrared sensing application, as a role model for Ge-based nanoelectronics passivation or for nonvolatile memory devices. The capability of the size control of those nanocrystals via rapid thermal processing of superlattice structures is shown for the [Ge–TaZrOx/TaZrOx]n, [Ge–TaZrOx/SiO2/TaZrOx]6, and [TaZrOx/Ge–SiO2]n superlattice systems. All superlattices were deposited by radiofrequency magnetron sputtering. Transmission electron microscopy (TEM) imaging confirms the formation of spherically shaped nanocrystals. Raman scattering proved the crystallization of Ge above 700°C. The TaZrOx crystallizes above 770°C, associated with a phase separation of Ta2O5 and ZrO2 as confirmed by x-ray diffraction. For the composite layers having 3 nm and 6 nm thickness, the size of the Ge nanocrystals correlates with the deposited layer thickness. Thicker composite layers (above 9 nm) form two fractions of nanocrystals with different sizes. An additional SiO2 layer in the [Ge–TaZrOx/SiO2/TaZrOx]6 superlattice stacks facilitates the formation of larger and better separated Ge nanocrystals. The deposition of Ge-SiO2 composite layers separated by pure TaZrOx illustrates the barrier effect of TaZrOx against Ge diffusion. All three material systems allow the controlled formation of Ge nanocrystals in amorphous matrices at temperatures above 700 and below 770°C. Graphical abstract

Enhancing Short-Wave Infrared Photosensitivity of SiGe Nanocrystals-Based Films through Embedding Matrix-Induced Passivation, Stress, and Nanocrystallization

“…Besides co-sputtering deposition of a single film, the other approach of depositing MLs has important advantages, i.e., control of NCs size by varying the thicknesses of component layers, hindered Ge diffusion and controlled NC position by using the oxide layers as spacers. ,, SiGe/TiO 2 MLs were prepared by depositing 6 pairs of [Ge­(5 nm)/SiGe­(21 nm)/Ge­(5 nm)/TiO 2 (10 nm)] layers stacks on p-Si also using the magnetron sputtering technique (Table S3). In the layers stack, 5 nm Ge layers ensure obtaining Ge-rich SiGe NCs (Ge supply) after RTA against fast Ge diffusion .…”

Effect of dopant loading and calcination conditions on structural and optical properties of ZrO2 nanopowders doped with copper and yttrium

“…Zirconia (ZrO 2 ) is a versatile material available in various forms, such as crystals [1,2], ceramics [3,4], films [5], and (nano)powders [6,7]. ZrO 2 possesses unique mechanical, electrical, thermal, and optical properties, making it suitable for a wide range of applications, including high-temperature and corrosion-resistant coatings, radiation detectors, biological labeling, catalysts, oxygen sensors, and solid-oxide fuel cells [ [7] and references therein].…”

“…ZrO 2 possesses unique mechanical, electrical, thermal, and optical properties, making it suitable for a wide range of applications, including high-temperature and corrosion-resistant coatings, radiation detectors, biological labeling, catalysts, oxygen sensors, and solid-oxide fuel cells [ [7] and references therein]. However, for many critical applications, pure ZrO 2 may be insufficient, and its doping or alloying with other metal oxides can be required [1][2][3][4][5][6][7][8][9][10]. The addition of complementary cations to the crystal lattice of zirconia can significantly alter its properties [1,[5][6][7].…”

“…However, for many critical applications, pure ZrO 2 may be insufficient, and its doping or alloying with other metal oxides can be required [1][2][3][4][5][6][7][8][9][10]. The addition of complementary cations to the crystal lattice of zirconia can significantly alter its properties [1,[5][6][7].…”

“…This phase is stable upon powders cooling. Since application of powders requires stability of the t-and c-phases not only at room temperature but also at higher temperatures, doping ZrO 2 with subvalent cations is employed [1][2][3][4][5][6][7][8][9][10][11][12][13][14].…”