SiGeSn growth studies using reduced pressure chemical vapor deposition towards optoelectronic applications

Abstract

ABSTRACT:In this contribution, we propose a laser concept based on a double heterostructure consisting of tensile strained Ge as the active medium and SiGeSn ternaries as cladding layers.

Direct Bandgap Group IV Epitaxy on Si for Laser Applications

“…The here extracted activation energy of about 0.7 eV is slightly higher than the value of 0.6 eV reported in Ref. 22 . The difference may arise from the investigated sample thicknesses: below 100 nm in Ref.…”

“…The difference may arise from the investigated sample thicknesses: below 100 nm in Ref. 22 and above 750 nm in this work. The impact of the layer thickness on the growth rate of Ge 0.875 Sn 0.125 alloys at growth temperature of 350°C is shown in Fig.…”

Epi-cleaning of Ge/GeSn heterostructures

“…3(b), where we present two AFM images of the as-received sample (bottom-left) and of the 300 Cannealed sample (top-right) together with their corresponding XRR spectra. The surface morphology shows the characteristic [110]-aligned cross hatch pattern due to the plastic relaxation of the underlying virtual substrate 6 with nearly identical roughness (RMS roughness $1 nm in an analyzed area of 100 lm 2 ). Moreover, the top Ge layer thickness is only slightly affected by the activated H removal of the surface contamination as determined by XRR analysis.…”

“…High quality (Si)GeSn epitaxy has been presented in previous investigations. 6 The lattice parameter of GeSn strain-relaxed buffers (SRBs) is given by the degree of strain relaxation and the Sn content, which can be precisely tuned by varying the growth temperature. In order to increase the in-plane lattice constant of SRBs, 200-300 nm thick layers have been grown, that is exceeding the critical thickness for strain relaxation.…”

“…[2][3][4] In these systems, owing to the a-Sn vs Ge lattice mismatch ($14%), the GeSn relaxed buffer layer induces in Ge a biaxial tensile strain parallel to the sample surface e par , which profoundly modifies its band structure, transforming it in a quasi-direct band gap semiconductor for e par > 1.6%. 5 Progress in out-of equilibrium epitaxy has made available wafer-size Ge/GeSn virtual substrate deposited on Si(001) with Sn content in excess of 10% 6,7 but their use is still limited mainly because of the inherent difficulties of a cleaning procedure for the Ge epi-layer compatible with thermodynamical constrains of the GeSn system, which will be discussed in the following.…”