Influences of temperature and low-dimensional interface phonons on the effective mass of a polaron in a quantum well

The temperature dependence of the effective mass of a polaron, which is weakly coupled with bulk longitudinal optical (LO) phonons and strongly coupled with interface optical (IO) phonons in an infinite quantum well (QW), are studied by means of the Tokuda modified linear-combination operator method and the modified Lee-Low-Pines variational method. The expressions for the effective mass of the polaron as a function of the well width and temperature are derived. Numerical results show that the total effective mass of the polaron is composed of two parts: one part is the polaron effect induced by the interaction of the electron with LO-phonons, and the other part is the effective mass of the polaron caused by the interaction of the electron with IO-phonons. In particular, among four branches of IO phonons, only two branches interacting with electrons with the frequencies ω++ω++ and ω-+ω-+ make contributions to the effective mass of the polaron. Numerical result for KI/AgCl/KI QW shows that the IO phonons dispersion has an obvious influence on the interaction between the electron and the phonons. The contributions of the interactions between the electron and the different branches of phonons to the effective mass of the polaron and the changes of the effective mass with well width and temperature are markedly different.