Carrier mediated reduction of stiffness in nanoindented crystalline Si(100).

We report the observation of carrier mediated decrease in the stiffness of crystalline (c)-Si(100) under nanoindentation. The apparent elastic moduli of heavily doped (~1 × 1021 cm-3) p- and n-type c-Si are observed to be lower by 5.3%-7.5% than the estimated value for intrinsic (~1 × 1014 cm-3) c-Si. The deviation observed with respect to elastic modulus remarkably matches with the estimated value while considering the electronic elastic strain effect on carrier concentration as an influence of negative pressure coefficient of band gap for Si (Γ-X). The value is predominantly higher than the reported value of a decrease of 1%-3% in stiffness as an effect of impurity in c-Si. [ABSTRACT FROM AUTHOR]