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DOE OSTI2020

Materials Data on GeCl4 by Materials Project

GeCl4 is Silicon tetrafluoride-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four germanium tetrachloride molecules. Ge4+ is bonded in a tetrahedral geometry to four Cl1- atoms. There are one shorter (2.13 Å) and three longer (2.14 Å) Ge–Cl bond lengths. There are four inequivalent Cl1- sites. In the first Cl1- site, Cl1- is bonded in a single-bond geometry to one Ge4+ atom. In the second Cl1- site, Cl1- is bonded in a single-bond geometry to one Ge4+ atom. In the third Cl1- site, Cl1- is bonded in a single-bond geometry to one Ge4+ atom. In the fourth Cl1- site, Cl1- is bonded in a single-bond geometry to one Ge4+ atom.

36 MATERIALS SCIENCE↗

NASA NTRS1976

Crystal growth from the vapour phase (ASTP experiment MA-085)

The positive effects of microgravity on crystal quality and fundamental properties of the vapor transport reaction were established by analyzing the results of three transport experiments on multi-component systems performed during the Apollo Soyuz Test Project (ASTP) mission. The systems employed were GeSe(0.99)Te(0.01) - GeI4 (A), GeS(0.98)Se(0.02) - GeCl4 (B), and GeS - GeCl4-Ar (C). The crystallographic analysis is based on a direct comparison of space and ground-based (prototype) crystals, employing X-ray diffraction, microprobe, microscopic, and chemical etching techniques. The results demonstrate a considerable improvement of the space-grown crystals in terms of chemical and crystalline homogeneity, surface morphology, and bulk perfection relative to ground specimens. The confirmation of greater mass transport rates than predicted for micro-gravity by present vapor transport models is of basic scientific and practical importance for the improvement of transport models and techniques on earth and for the development of a transport model for space conditions. The internal consistency and agreement between ASTP and Skylab results obtained for different compounds, transport agents, and temperature gradients strongly support the validity of these observations. The combined findings of improved crystal quality and high mass transport rates are of technological significance for space-processing applications.

Wiedemeier, H.↗

NASA NTRS1977

Crystal growth from the vapor phase. Experiment MA-085

The positive effects of microgravity on crystal quality and the fundamental properties of the vapor transport reaction were established by analyzing the results of three transport experiments on multicomponent systems performed during the Apollo-Soyuz Test Project mission. The systems employed were GeSe0.99Te0.01-GeI4(A), GeS0.98Se0.02-GeCl4(B), and GeS-GeCl4-Ar (C). The crystallographic analysis is based on a direct comparison of space and ground-based (prototype) crystals employing X-ray diffraction, microprobe, microscopic, and chemical etching techniques. The results demonstrate a considerable improvement of the space-grown crystals in terms of chemical and crystalline homogeneity, surface morphology, and bulk perfection relative to ground specimens.

Wiedemeier, H.↗

NASA NTRS1994

Epitaxial Deposition Of Germanium Doped With Gallium

Epitaxial layers of germanium doped with gallium made by chemical vapor deposition. Method involves combination of techniques and materials used in chemical vapor deposition with GeH4 or GeCl4 as source of germanium and GaCl3 as source of gallium. Resulting epitaxial layers of germanium doped with gallium expected to be highly pure, with high crystalline quality. High-quality material useful in infrared sensors.

Huffman, James E.↗