Confined LO phonon limited free carrier absorption in quantum well wires

Abstract

The theory of free-carrier absorption is given for quantum well wire for the case where the carriers are scattered by confined longitudinal-optical (LO) phonons and the radiation field is polarized along the length of the wire. Both the multisubband structure and confined phonon modes are considered together. The free carrier absorption coefficients are calculated taking into account all possible LO phonon modes as well as all possible electron intersubband transitions. The results show that the absorption coefficient decreases with increasing the photon frequency and decreases with temperature. It was found that in quantum wire the electron-optic phonon interaction give a greater contribution to the absorption than the electron-confined LO phonon interaction. The results are interpreted in terms of confined LO phonons-assisted transitions between size quantized subbands.