Single-fabrication-step Ge Nanosphere/SiO<inf>2</inf>/SiGe heterostructures: A key enabler for realizing Ge MOS devices

Self-Organized Ge Nanospherical Gate/SiO2/Si0.15Ge0.85–Nanosheet n-FETs Featuring High ON-OFF Drain Current Ratio

“…The resulting Si 1−x Ge x -nanosheet is formed as a consequence of the release of the free energy from the dissolution of Ge within the originally pure Si layer. Therefore, the thickness and the Ge composition of the Si 1−x Ge x -nanosheet are essentially determined by kinetics based on the factors such as the Ge nanosphere size and its depth of penetration into the Si substrate that determine the Ge interstitial flux generation and diffusion through the Si substrate [23]. A high degree of crystallinity is obtained for our 5.5nm-thick SiGe nanosheet as evidenced by neither visible lattice defects nor faceting observed from TEM micrographs in Fig.…”

“…2(b)) and Raman analysis. Estimated values for Ge composition (x) and compressive strain (ε) are x ≈ 0.85 and ε ≈ −2.2%, respectively [23].…”

“…This single-step fabrication process is enabled by a unique combination of Si interstitials-mediated SiO 2 "destruction-construction" mechanism [19] as well as by a rather curious, "symbiotic" interplay of Ge, Si and O interstitials at 800 − 900 • C [20]. Our previous reports have already demonstrated a good control of (1) the diameters (10nm−100nm) of the Ge NPs (the channel length/width), [21] (2) the thickness (2.5-4.8 nm) of the SiO 2 (gate oxide) layer, [22], [23] and most importantly, (3) the crystal orientation, chemical composition, and the strain state of Si 1−x Ge x -shell (channel) over Si substrates [23] by tailoring geometrical dimensions of lithographically-patterned Si 1−y Ge y nanopillars and conditions of thermal oxidation. Using this approach, a single-crystalline (100) Si 1−x Ge x nanosheet with a Ge content as high as x = 0.85 in a compressively-strained state of 2.5% is achievable on SOI (100) substrates as assessed by transmission electron microscopy (TEM), Raman spectroscopy and selected-area nano-beam diffraction (NBD) patterns examinations [21]- [23].…”

“…Our previous reports have already demonstrated a good control of (1) the diameters (10nm−100nm) of the Ge NPs (the channel length/width), [21] (2) the thickness (2.5-4.8 nm) of the SiO 2 (gate oxide) layer, [22], [23] and most importantly, (3) the crystal orientation, chemical composition, and the strain state of Si 1−x Ge x -shell (channel) over Si substrates [23] by tailoring geometrical dimensions of lithographically-patterned Si 1−y Ge y nanopillars and conditions of thermal oxidation. Using this approach, a single-crystalline (100) Si 1−x Ge x nanosheet with a Ge content as high as x = 0.85 in a compressively-strained state of 2.5% is achievable on SOI (100) substrates as assessed by transmission electron microscopy (TEM), Raman spectroscopy and selected-area nano-beam diffraction (NBD) patterns examinations [21]- [23]. The originality and salient features of our gate-stacking heterostructure lie in its inherent structural simplicity in combination with the process elegance of being simultaneously produced within a single oxidation step [18].…”

The amazing world of self-organized Ge quantum dots for Si photonics on SiN platforms

“…2) as it penetrates the LPCVD-Si 3 N 4 layer. The thickness of SiO 2 interlayers is essentially determined by a dynamic equilibrium existing between the local concentrations of O and Si interstitials near the Ge-QD/ Si 3 N 4 interface supplied by the external oxygen ambient and the Si interstitials released from the locally decomposing Si 3 N 4 layer [32].…”