Binding energy of a bound polaron in strong magnetic fields in low-dimensional semiconductor systems

Abstract

Ionization energies of a shallow donor in a quantum well (Q2D), quantum well wire (Q1D) and quantum box (Q0D) of the GaAs/Ga1-xAlxAs superlattice system in strong magnetic fields are obtained. The contributions from the electron-lattice coupling are also systematically investigated in all these systems. It is found that the ionization energy (Eion) (i) decreases with an increase in well width in Q2D, Q1D, and Q0D systems; (ii) increases with magnetic field for a given well width in all these systems, and (iii) increases as the spatial dimension is reduced for a given well width and magnetic field. The polaronic effect on Eion, that is, Delta Ee-1(B)/Eion( alpha =0,B) decreases when the magnetic field is increased in all three systems, showing a softening of the electron-lattice coupling. This decrease is more pronounced in Q2D than in Q1D or Q0D. The polaronic shift is also seen to be more important for systems with a smaller well width. The results are discussed in the light of the existing literature on these systems wherever available.