Investigation of Si–Ge whisker growth by CVD

Abstract

The present paper deals with study of Si 1-x Ge x (x = 0 ÷ 0.11) whiskers growth in sealed Si -Ge -Br systems by CVD method. An influence of multiple doping (Zn, Hf, Ni, Mn) on morphology of the whiskers was investigated. A model based on evaluation of impurity activity coefficients in Si crystals was proposed. High impurity activity coefficients were established to correspond to submicron whisker growth. As the impurity activity coefficient decreases, the whisker morphology changes from twinned ribbon to needle-like crystals with perfect surface of facets.

Variable‐range hopping conductance in Si whiskers

“…To verify this assumption let us check the Mott law for the analyzed samples. As it is known from Mott's law, at finite density of states at the Fermi level N(E F ) low-temperature electron transport occurs by tunneling jumps with variable hopping impurity with radiation or absorption of phonons [10]. In our experiments, the resistivity of the samples with r 300K ¼ 0.0168 V cm obeys the Mott law, since linear dependence ln(r) ¼ f(T À1/4 ) is observed (see Fig.…”

Magnetic susceptibility and magnetoresistance of neutron-irradiated doped SI whiskers

“…Si whiskers were grown by the chemical transport reaction method in a sealed bromide tube [10]. In quartz tube the following materials were loaded: silicon -growth materials; gold -initiator of growth; boron -doping impurity and bromine -transport agent.…”

Thermoelectric Properties of Oblique SiGe Whiskers

“…For the thickest studied samples the ZT at room temperature still remained very low -only 6.4  10 -3 . On the other hand, the observed peculiarities may be related with the spatial inhomogeneity of dopant impurity distribution or germanium content along the whisker, which is a typical consequence of unstable conditions of whiskers' growth via the vapor-liquidsolid mechanism upon chemical vapor deposition [16]. At the initial stages the velocity of crystal growth is maximum, the growth is tempestuous and nonequilibrium, so that big amounts of impurity atoms are captured, while their spatial distribution is highly nonuniform.…”