Abstract: A variational approach is used to study the polaron effect from both the abnormal optical LO-like and TO-like phonons on the binding energies of impurity states in wurtzite nitrides semiconductor crystals by considering the uniaxial anisotropy.Taking the variations of electronic effective mass,material dielectric constants and crystal lattice vibrational frequencies with hydrostatic pressure into account,the pressure effect on the binding energy of bound polaron is discussed.The numerical results show that the polaron effect obviously decreases the binding energy,and the contributions from impurity-LO-like phonon interaction to the polaron effect are dominant.It is also found that pressure enhances the binding energy and its anisotropy.

Key words: binding energy, polaron, nitrides semiconductors