The incorporation of phosphorus in amorphous silicon

Abstract Amorphous films of SiP alloys were prepared by plasma deposition in an rf gas discharge of mixtures of SiH 4 and PH 3 . The relative gas phase content of PH 3 was varied between 5·10 −5 and unity. The phosphorus incorporation ratio was determined by neutron activation analysis and atomic absorption spectroscopy; it decreases from about 6 at low concentrations to unity at high concentrations. The films were characterized by measurements of the dark conductivity and its activation energy. - To explain our results we propose that, in the range of P contents investigated, most of the P atoms are 3-fold coordinated; a small fraction is 4-fold coordinated and accounts for the doping.