High-speed droplet migration in silicon

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Abstract
High‐temperature thermomigration of aluminum‐rich droplets in silicon has results in droplet migration rates up to 10 cm/day. These unexpectedly high rates are an order of magnitude greater than those previously reported in the liturature. The large enhancement of dorplet migration rates at high temperatures is shown to be caused by a substantial increase in the flow of liqudi across the droplet and by a favorable variation in the change of the composition of the liquid at hgih temperatures. The variation of droplet velocity with droplet size is reported over a large range of droplet sizes and temperatures for both the 〈100〉 and 〈111〉 migration directions in silicon. The undersaturation and supersaturation required to make a (111) silicon plane dissolve and deposit, respectively, are calculated from the data. Finally, fromthe velocity of large droplets, the liquid interdiffusion coefficient for the aluminum‐silicon system is determined.