WORK FUNCTION AND ENERGY-LEVELS OF POSITRONS IN ELEMENTAL SEMICONDUCTORS

We have studied the behaviour of the positron in diamond, silicon and germanium by calculating its energy levels at different points of the reciprocal space using the pseudopotential approach coupled with the i ndependent particle approximation. These energies determine quantities , such as the positron and positronium work functions and the deformat ion potentials, which are important parameters in slow-positron-beam e xperiments. We have tentatively estimated the positron diffusion const ant in these semiconductors. The results are compared to values extrac ted from experiments.