Energy band gap and phonon frequency in semiconductors are material constants?

摘要

We report both Raman shift and photoluminescence (PL) in Ge as a function of carrier density instead of dopant concentration. The results show both the energy band gap (Eg) and zone-centered phonon frequency are dependent on free carrier density. In the low voltage device operation, it should be taken into consideration that material constants so far accepted are not really constant anymore.