Lattice matched GeSn/InAlAs heterostructure: role of Sn in energy band alignment, atomic layer diffusion and photoluminescence

Abstract

Germanium alloyed with α-tin (GeSn) transitions to a direct bandgap semiconductor of significance for optoelectronics. It is essential to localize the carriers within the active region for improving the quantum...

GeSn-on-GaAs with photoconductive carrier lifetime >400 ns: role of substrate orientation and atomistic simulation

“…Using b Ge0.94Sn0.06 = 314.81 ± 14 cm −1 from ref. 17, the in-plane biaxial compressive strain is calculated to be ∼0.84 ± 0.03%, which is in agreement with the strain value of ∼0.81% from X-ray analysis above (Fig. 2).…”

“…In the present work, the amount of compressive strain in epitaxial Ge 0.94 Sn 0.06 layer of sample A1 is calculated using the b value of a lattice matched Ge 0.94 Sn 0.06 /In 0.12 Al 0.88 As/GaAs(100)/2° heterostructure system, previously demonstrated, 17 that has an unstrained crystal lattice of 350 nm Ge 0.94 Sn 0.06 layer in which the measured LO phonon Raman wavenumber was determined as, ω 0 = 297.05 ± 0.03 cm −1 . The lattice matched Ge 0.94 Sn 0.06 sample referred to above is the same substrate orientation of sample A1 (compressive), enabling us to calculate the biaxial compressive strain.…”

“…Deviation of the LO phonon peak with respect to this position is determined as the strain state (compressive or tensile) of the layer. 43,44 Strain-induced Raman wavenumber shifts due to the phononic deformation potentials were determined by taking the lattice matched Ge 0.94 Sn 0.06 sample as a reference, 17 that was synthesized in the same MBE system as the other associated strained Ge 0.94 Sn 0.06 samples (A1, B2, and C), studied in this work. Cross-sectional transmission electron microscopy analysis was performed on sample A2, as a representative material quality characterization, using the Thermo Scientific Themis 300 G3 instrument having an accelerating voltage of 300 kV and a point resolution of 0.2 nm.…”

“…4–8,10,12,14,15 However, device quality Ge 1− y Sn y materials on silicon (Si) with low defect density and high carrier lifetime are in their infancy. Researchers are looking for an alternative approach to produce GeSn materials with high carrier lifetimes: either lattice matched to underlying substrate or buffer layer 16–18 or compressively strained GeSn layers. 7,8,14 Among these approaches, substrate orientation and misorientation mediated GeSn materials with high carrier lifetime and low defect density have never been demonstrated.…”

“…19,21 In addition, the epitaxial Ge layers when grown on oriented and misoriented GaAs substrates exhibit different materials properties 24–26 and metal–oxide-semiconductor capacitor properties. 27,28 For instance, carrier lifetime can affect optoelectronic device performances such as internal quantum efficiency, responsivity, and heterojunction leakage in a photodetector, 1,2,17 and internal/external quantum efficiency, optical gain, and material loss in a laser. 1,2 In addition, high carrier lifetime signifies low leakage current due to D it and N ss in a transistor.…”