The Growth of Whiskers

A typical case is the growth of silver whiskers by cathodic reduction from concentrated silver nitrate solutions (0.3 M) containing certain organic additives such as oleic acid, gelatine, albumin, or n-heptyl, n-octyl, and -nonyl alcohols, or, from silver nitrate solutions aged for several weeks. Copper whiskers can be grown from solutions containing a variety of additives or hydroxylamine ions in the presence of chlorides. 

It appears that the following set of phenomena is generally met in the growth of whiskers  

An equation was derived based on such a model. It defines the critical current density as 

The theory seems to be in good agreement with experiment, with the order-of-magnitude calculation of A being based on independently assessed parameters. 

The minimum time of interruption could also be calculated, assuming this to be equal to the time needed to block the surface completely by adsorption of the additive. This is, then. 

---

This point of view regarding the role of adsorbed impurities at the steps follows closely the idea first suggested by Price, Webb, and Vermilyea (8) to explain the growth of whiskers. The production of a high local curvature is believed to be the important point rather than the fact that the impurities will be adsorbed preferably at the kink sites in fact, this will clearly not reduce the number of kink sites because new ones will be produced. 

The vaporization-condensation of B4C at 2223 K in vacuum allows the growth of whiskers, metallic impurities catalyzing the growth " . 

Vapor-phase techniques are not as widely used as growth from the melt or solution because the growth rate is generally slow or only small crystals can be grown. However, two vapor-phase techniques have commercial application the growth of whiskers or small islands (e.g., SiC and GaN) by the VLS process and the growth of SiC and nanotubes by sublimation processes. 

It should be noted that the migration of gold from the drop can occur in silicon nanowhiskers at high temperatures. Similar conclusions can be made from the results of simulation. This phenomenon is also observed in simulation of the processes of the growth of whiskers by the Monte Carlo methods [21] and in our calculations (Fig. 5.7). These data also show a good coordination of simulation results with experiments and other methods of computer simulation. 

Fig. 19 A schematic diagram of the growth of whiskers of diameter of 2a and a separation of 2b on a planar...

---