BINDING-ENERGY OF D- IONS IN SI AND GE

A formulation is presented to find the electronic states of a D- centr e in a many-valley semiconductor. Parameterizing the intervalley scatt ering terms and using a model potential in the central cell region the D- binding energies in Si and Ge doped with group V elements are calc ulated variationally, including electron correlation. The binding ener gy obtained for Si:P and Ge:Sb are in good agreement with experimental results. D- formed by As donors appears to require a more detailed co nsideration for the central cell potential.