An Optical Determination of the Ground-State Splittings of Group V Impurities in Germanium

A method is described by which direct and accurate values are obtained for the energy separations, $4\Delta$, of the singlet and triplet ground states of Group V impurities in germanium. The method relies on measuring the energy difference between optical absorption lines which are due to transitions from both ground states to the same excited state of an impurity. With the values of $4\Delta$ so found and the values of $\frac{4\Delta }{E_2}$ given by other workers, values of the shear deformation potential constant $E_2$ are obtained. Also observed for each impurity is a shift of the triplet state to an energy which is lower than that given by the effective-mass formalism. This shift is found to be almost the same for all the Group V impurities.