If Cs and Cl are the equilibrium concentration of impurities in the solid and liquid near the interface respectively, then for dilute solutions encountered in silicon growth, an equilibrium segregation coefficient k0 may be defined as:

 

8) If C_s and C_l are the equilibrium concentration of impurities in the solid and liquid near the interface respectively, then for dilute solutions encountered in silicon growth, an equilibrium segregation coefficient k₀ may be defined as:

1. C_s / C_l
   
   
2. C_l / C_s
   
   
3. C_s - C_l
   
   
4. (C_s - C_l) / C_l
   

Answer: A

Solution

When making silicon wafers for computer chips, we start with a vat of molten (liquid) silicon. We then slowly "grow" a solid crystal from this melt. To make the silicon conduct electricity, we add "impurities" (dopants like Boron or Phosphorus).

As the liquid silicon turns into solid silicon at the interface (the boundary where they meet), the impurities don't distribute themselves equally.

Some impurities "prefer" to stay in the liquid.

Some "prefer" to move into the solid.

This "preference" is what we call segregation.

Cs
: The concentration of the impurity in the Solid phase.

Cl
: The concentration of the impurity in the Liquid phase.

Segregation Coefficient (k0​)=Concentration in LiquidConcentration in Solid​=Cl​Cs​

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