Structural and optical characterization of SixGe1−x−ySny alloys grown by molecular beam epitaxy

Abstract

SixGe1−x−ySny alloys were grown by molecular beam epitaxy at low temperature, followed by ex-situ annealing. The crystal quality of SixGe1−x−ySny layers was characterized by atomic force microscopy and transmission electron microscopy. The compositions and lattice constants of the alloys were studied by x-ray photoelectron spectroscopy and x-ray diffraction. The results show that Vegard’s law is a good approximation for SixGe1−x−ySny alloys. Photoreflectance spectroscopy at room temperature was used to determine the direct bandgap energy of SixGe1−x−ySny layers. Analyzing the relationship between composition and direct bandgap energy reveals a negative energy bowing parameter for SiSn.

Growth and applications of GeSn-related group-IV semiconductor materials

“…The crystal growth of Ge 1−x−y Si x Sn y ternary alloy thin films with MBE [80,81] and CVD [46,75] methods has been reported. Recently, we reported the epitaxial growth of Ge 1−x−y Si x Sn y layers whose lattice matches that of a Ge(001) substrate using the MBE method [81,82].…”

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

“…However, the use of strained Ge (sGe) as active laser medium demands also the development of suitable barrier layers in order to confine the charge carriers and achieve population inversion. The group IV SiGeSn alloys are ideal candidates to be employed as cladding layers due to the possibility of modifying the lattice constant and bandgap, independently [8,9]. Due to the low solid solubility of Sn in Ge (< 1%) [10] and the strong tendency for surface segregation of Sn, low growth temperatures have to be used.…”

Silicon-based silicon–germanium–tin heterostructure photonics

“…Si/GeSn/Si represents a lattice-mismatched strategy in which the GeSn has dislocations at both of its hetero-interfaces. Lin et al [27] grew SiGeSn on InGaAs. The MSI theory paper gives design rules for type-1 direct-gap MQW photonic structures operating in the 2.8-6.2 μm range.…”