Asymmetric polarization induced by strong electric field on spherical semiconducting particles

A spherical conductive particle immersed in a uniform electric field acquires a charge distribution that displays odd symmetry with respect to the equatorial plane perpendicular to the applied field, while the internal field exhibits even symmetry. This configuration in symmetry is preserved in metal particles for a large intensity applied field, owing to the abundance in electrons. In extrinsic semiconductor particles, this symmetry is not maintained when the applied field approaches high intensity (∼104 V/cm for a dopant concentration of 10¹⁷ cm⁻³) as a result of depletion of mobile charge carriers (electrons or holes) in one of the hemispheres. While the mobile charges are able to congregate close to the surface on one side of the particle, the exposed dopant ions on the opposite side are unable to migrate, resulting in the broken symmetry when the applied field reaches a certain intensity.