Silicon vapor phase epitaxial growth catalysis by the presence of germane

Abstract

Experiments involving the epitaxial growth of GexSi1−x films by chemical vapor deposition have shown that the addition of germane greatly enhances the growth rate, compared to that seen with dichlorosilane alone. Careful analysis shows that the increase is not accounted for by summing the individual growth rates, but clearly indicates that the silicon growth rate is catalyzed. The magnitude of the effect increases at lower temperatures, with a two orders of magnitude increase seen at 625 °C.

Si1−xGex growth using Si3H8 by low temperature chemical vapor deposition

“…Fig. 3(c) The enhancement of the Si component deposition rate by adding GeH4 called "Ge catalytic effect" [12] is clearly seen in Si1-xGex growth using SiH4 in H2. However, for the other three cases, the effect is relatively weak, especially in the case of Si1-xGex growth using Si3H8.…”

Kinetics of germanium nanowire growth by the vapor-solid-solid mechanism with a Ni-based catalyst

“…Various studies of surface reaction limited growth of Ge thin films report activation energy values such as 0.21 eV, 26 0.38 eV, 27 and 0.91 eV. 23 The activation energy for Au catalyzed Ge whisker growth via the VLS mechanism was reported to be 0.18 eV where the growth was limited by surface reaction.…”

“…As described previously, when the chemical vapor deposition rate of thin films is different in two different regimes, growth is typically limited by surface reaction at lower temperatures and mass transport of the precursor at higher temperatures. 23,26,27 The "surface reaction step" comprises a number of reactions such as desorption of hydrogen from the surface, dissociation of germane, and adsorption of Ge on the surface. When the growth is said to be surface reaction limited, any of these reactions could be rate limiting.…”

“…Similar behavior is often reported for chemical vapor deposition of Si or Ge thin films. 23,26,27 Two temperature regimes of VLS growth were also reported previously for gold catalyzed Ge nanowire growth in the same CVD reactor. 24 Figure 3 temperature, consistent with a single kinetic mechanism, uncatalyzed Ge deposition as a result of dissociative adsorption of GeH 4 , over the studied temperature range of 300…”

“…1, which include dissociative adsorption of germane, diffusion of Ge across the catalyst, or incorporation of Ge at the growth step, are all expected to depend on temperature too strongly to be consistent with this low activation energy. Therefore, it can be concluded that, in the higher temperature regime, vapor phase diffusion of GeH 4 precursor to the catalyst surface, which should be weakly dependent on the temperature, 27 is likely rate limiting. Similarly, at temperatures >320…”