ABSTRACT
This chapter shows that stable bipolarons can indeed form in realistic quantum dots of polar semiconductors like GaAs, CdS, CdSe, and CdTe. Pokatilov et al. have investigated the stability of bipolarons by applying Feynman's variational principle and have shown that in a quantum dot bipolaron states are possible even for intermediate values of the electron-phonon coupling constant. Krishna, Mukhopadhyay have studied the quantum dot bipolaron problem for the entire range of the coupling constant using the Lee-Low-Pines-Huybrechts method. Senger et al. have recently made an interesting investigation on the stability of a bipolaron in spherical quantum dots using a single Hamiltonian and a variational method. In GaAs the bipolaron is barely stable whereas according to the theory, bipolarons cannot exist in InSb quantum dot. One can also perform tunnelling experiments in a quantum dot array wherefrom the charge of the tunnelling particles will shed light on the nature of the quasi-particles.
