[填空题]
For an arsenic donor 8bgi6bdlgz:-ql(n x*8 l aum;atom in a doped silicon sem8yfrnje8klq a/x63mwc9m696 t- semgiconductor, assume that the "extra" electron moves in a Bohr orbit about tkjeywg 66mr8q n emx9a3l9s/cmt8-f6 he arsenic ion. For this electron in the ground state, take into account the dielectric constant $ K = 12 $ of the Si lattice (which represents the weakening of the Coulomb force due to all the other atoms or ions in the lattice), and estimate
(a) the binding energy, E = eV
(b) the orbit radius for this extra electron. r = nm
