Synthesis of Silicon-Based Infrared Semiconductors in the Ge−Sn System Using Molecular Chemistry Methods

Abstract

Growth reactions based on a newly developed deuterium-stabilized Sn hydride [(Ph)SnD(3)] with Ge(2)H(6) produce a new family of Ge-Sn semiconductors with tunable band gaps and potential applications in high-speed, high-efficiency infrared optoelectronics. Metastable diamond-cubic films of Ge(1-x)Sn(x) alloys are created by chemical vapor deposition at 350 degrees C on Si(100). These exhibit unprecedented thermal stability and superior crystallinity despite the 17% lattice mismatch between the constituent materials. The composition, crystal structure, electronic structure, and optical properties of these materials are characterized by Rutherford backscattering, high-resolution electron microscopy, and X-ray diffraction, as well as Raman, IR, and spectroscopic ellipsometry. Electron diffraction reveals monocrystalline and perfectly epitaxial layers with lattice constants intermediate between those of Ge and alpha-Sn. X-ray diffraction in the theta-2theta mode shows well-defined peaks corresponding to random alloys, and in-plane rocking scans of the (004) reflection confirm a tightly aligned spread of the crystal mosaics. RBS ion-channeling including angular scans confirm that Sn occupies substitutional lattice sites and also provide evidence of local ordering of the elements with increasing Sn concentration. The Raman spectra show bands corresponding to Ge-Ge and Sn-Ge vibrations with frequencies consistent with random tetrahedral alloys. Resonance Raman and ellipsometry spectra indicate a band-gap reduction relative to Ge. The IR transmission spectra suggest that the band gap decreases monotonically with increasing Sn fraction. The synthesis, characterization, and gas-phase electron diffraction structure of (Ph)SnD(3) are also reported.

Lattice location study of ion implanted Sn and Sn-related defects in Ge

“…I, it is clear that the Sn atoms prefer the S site to the other high-symmetry sites. This is consistent with previous experiments where the majority of Sn atoms were found on the S site 11,12 , with our emission channeling results and with what one would expect for isovalent impurities. Although the heats of formation in Tab.…”

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

“…Kouvetakis's group proposed using SnD 4 as a precursor because SnD 4 is more stable than SnH 4 , which has autoproteolysis characteristics. They reported the epitaxial growth of unstrained Ge 1−x Sn x layers with an Sn content from 2 to 15% on Si(001) substrates using the low-pressure CVD method at 250-350°C with a combination of the precursors SnD 4 and Ge 2 H 6 [44][45][46]. They also reported CVD growth with the combination of Ge 3 H 8 and SnD 4 precursors for lowering the growth temperature of Ge 1−x Sn x layers [11].…”

Electrodeposition of Ge, Sn and GexSn1-x from two different room temperature ionic liquids

“…It was predicted to possess a tuneable direct band gap [5,6] and thus has some potential applications in infrared (IR) devices [7,8]. Quantum confinement effects have also been observed in Ge x Sn 1-x quantum dots [9].…”