Diffusivity and Solubility of Copper in Germanium

Abstract

The diffusivity and solubility of Cu in Ge have been investigated as a function of temperature in the temperature range 700°-900°C, both by resistivity and radio-activity methods. The average diffusivity is 2.8±0.3X10~5 cm 2 /sec in this temperature interval. The solubility shows a maximum of 4.0X10 16 atoms of copper cm -3 at about 875°C. The precision is not sufficient to determine an activation energy for diffusion. However, calculations based upon a theory of Wert and Zener, indicate an activation energy of about 4000 cal. The "thermal conversion" effect in Ge is explained by a temperature-dependent solution and precipitation of Cu. It is suggested that the acceptor and diffusional properties of Cu in Ge can be accounted for by decreased electron affinity of Cu at higher temperatures.

High Density Germanium Nanowire Growth Directly from Copper Foil by Self-Induced Solid Seeding

“…The presence of Cu 3 Ge tips on the NWs confirms they are formed via a solid seeding mechanism as NW growth was conducted far below the Cu/Ge eutectic point of 644 °C. 34 The irregular seed geometry observed here has previously been noted for Cu 3 Ge seeded Ge NWs 12 and is in contrast to the typically observed, hemispherical seeds for Au seeded NWs. 32 Upon closer inspection, it was found that the Cu 3 Ge catalyst seeds had two specific orientations relative to the <110> NWs.…”

“…The presence of Cu 3 Ge tips on the NWs is a clear indicator that a VSS mechanism is responsible for the sub-eutectic growth presented (Cu/Ge eutectic point exists at 644 °C 34 ). We have shown that two specific seed orientations are responsible for the <110> grown NWs which is important given the recent interest in the transfer of crystallographic information from solid catalyst seeds to the resultant NWs.…”

Effects of copper diffusion in gallium arsenide solar cells for space applications

“…Such a trap level is a potential non-radiative recombination pathway [11,12]. However, while Cu diffusion and the effects of Cu in large semiconductor crystals are described elaborately in literature [13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29], there is virtually no literature on the effects of Cu diffusion on semiconductor devices such as solar cells.…”

Microstructure of high temperature–pressure treated nitrogen-doped Czochralski silicon

“…It has been reported that oxygen can improve the mechanical strength of Si crystal by inhibiting the glide of dislocations that may unintentionally be introduced during wafer processing. At around 450 • C, oxygen atoms in CZ-Si can form small electrically active agglomerates commonly known as "thermal donors", TDs [2]. Furthermore, oxygen atoms in CZ-Si subjected to heat treatments can aggregate to form oxygen precipitates in bulk Si, acting as "intrinsic gettering" centers for metallic impurities so that defect-free denuded zone can be generated.…”