Large enhancement of boron solubility in silicon due to biaxial stress

One of the important challenges to the semiconductor industry today is to enhance the solid solubility of several dopants, boron in particular, in silicon. We calculate the equilibrium solid solubility of boron in Si from first principles and examine the effect of biaxial stress. We find an unexpectedly large enhancement, on the order of 150%, for only 1% strain primarily due to the charge of the substitutional boron impurity in Si. We point out that this effect is an intrinsic property of Si and is expected to be important for other dopants as well.