Shallow-donor ionization energies in the II-VI compounds

Hall data on ZnSe, CdS, CdSe, and CdTe have been analyzed to determine the shallow-donor ionization energies $E_d$ and the total donor and acceptor impurity concentrations $N_d$ and $N_a$, respectively. Lowering of the $E_d$ values owing to impurity concentration effects are noted even in the purest samples. When the data are analyzed using linear plots of $E_d$ vs ${\left(N_{d^{+}}\right)}^{\frac{1}{3}}$, the resulting values of the ionization energy for infinite dilution are in good agreement with optical data and with the hydrogenic model.