Metastability and relaxation in tensile SiGe on Ge(001) virtual substrates

Abstract

We systematically study the heteroepitaxy of SiGe alloys on Ge virtual substrates in order to understand strain relaxation processes and maximize the tensile strain in the SiGe layer. The degree of relaxation is measured by high-resolution x-ray diffraction, and surface morphology is characterized by atomic force microscopy. The results are analyzed in terms of a numerical model, which considers dislocation nucleation, multiplication, thermally activated glide, and straindependent blocking. Relaxation is found to be sensitive to growth rate and substrate temperature as well as epilayer misfit and thickness, and growth parameters are found which allow a SiGe film with over 4 GPa of tensile stress to be obtained. V C 2014 AIP Publishing LLC.

Micro and nanofabrication of SiGe/Ge bridges and membranes by wet-anisotropic etching

“…Then, a tensile Si 1Àx Ge x film (0.6 6 x 6 0.9; thickness $ 10 nm) was grown on the Ge layer ( Fig. 1(a)) at temperatures between 450°C and 500°C [22]. The SiGe capping layer could eventually be patterned by e-beam lithography into a stressor for the underlying Ge [10].…”

Functionalization of Scanning Probe Tips with Epitaxial Semiconductor Layers

“…LEPECVD is a versatile variant of conventional CVD techniques, in which the use of the plasma parameters to enhance the deposition efficiency allows independent optimization of the growth rate (controlled by the plasma density) and of the mobility of the adatoms (controlled by the substrate temperature) . In this way, the main material science issue of Ge‐on‐Si epitaxy, which is the 4% larger lattice parameter of Ge if compared to Si, is circumvented by performing out‐of‐equilibrium growth of relatively thick strain‐relaxed heteroepitaxial Ge layers . Strain‐relaxed, heavily electron‐doped germanium (n‐Ge) films several micrometers thick (2–4 μm), are first grown have been grown on industrial‐grade Si substrates along the [001] crystal axis of Ge and Si by introducing simultaneously germane (GeH 4 ) and phosphine (PH 3 ) in the LEPECVD growth reactor, in order to incorporate P as a donor in the Ge crystal lattice.…”

Local uniaxial tensile strain in germanium of up to 4% induced by SiGe epitaxial nanostructures

“…The composition and strain state of both the Ge and SiGe layers were measured by highresolution x-ray diffraction (XRD) around the (0 0 4) and grazing-incidence (2 2 4) Bragg peaks; the Ge layer was found to be under 0.14% tensile thermal biaxial strain, and the SiGe layer was almost fully coherent with the Ge VS, with a degree of relaxation of only 5% corresponding to an in-plane tensile strain of 2.08%. 17 The same values of strain for SiGe and Ge can be obtained by Raman spectroscopy 19,20 with an excitation wavelength k exc ¼ 532 nm (Fig. 2(a)), which can probe simultaneously the SiGe layer and the Ge layer.…”

“…16, which can be summarized as follows. For what concerns the composition of the stressor, the growth of Ge-rich SiGe allows thicker stressors to be obtained without plastic relaxation, 17 but results in lower stress forces. For the thickness t, a thinner SiGe layer allows a fully strained stressor without plastic relaxation, while higher thickness means higher stress forces.…”