Blue and red Stark shifts in single Si/SiO2 quantum wells

The quantum-confined Stark shift (QCSS) of the ground and the first excited electron energy states in single Si/SiO2 quantum wells is calculated, The QCSS for the ground state is always negative (blue), while the QCSS for the first excited state is positive, in general, but it can turn out to be neg ative when the electric field intensity becomes high enough. A remarkable r eduction (similar to 50%) of the Stark shifts is obtained when the existenc e of nonabrupt interfaces as thin as 10 Angstrom is taken into account. The nonabrupt interfaces can also change the sign of the Stark shift in the ca se of the excited states. (C) 1999 Academic Press.