Popis: |
The polarizability and the ground state binding energy of a donor impurity located in a semiconductor quantum well wire of rectangular cross-section with finite barrier potential is calculated through the variational method. We assume that the donor is located at the center of the wire and that the electric field is applied in the direction perpendicular to the wire length ( z -direction), making an angle θ with the x -axis. We present our results for the ground state binding energy as a function of the size of the wire for several values of the electric field strength and of the angle θ. It is found that the polarizabilities decrease as the wire dimensions ( L x and L y ) decrease, until they reach a minimum at a certain value of L x ( L y fixed) and then increase as the width becomes smaller. The binding energies and the polarizabilities, as expected, have a strong dependence on the geometrical form of the wire and on the angle θ. |