NUCLEATION OF IN-SITU PHOSPHORUS-DOPED AMORPHOUS-SILICON FILMS DEPOSITED BY PYROLYSIS OF SI2H6 AND PH3

Nucleation of in situ phosphorus-doped amorphous Si films deposited by pyrolysis of Si2H6 and PH3 is studied by scanning laser microscopy an d transmission electron microscopy. The incubation time of the nucleat ion decreases as phosphorus concentration increases. The activation en ergy of the incubation time for nucleation, which corresponds to the a ctivation energy of the self-diffusion coefficient of amorphous Si, is ca. 3.2 eV, independent of phosphorus concentration. The nucleation r ate abruptly increases when the phosphorus concentration exceeds 4 x 1 0(20) cm-3. The activation energy of the nucleation rate decreases abr uptly above the phosphorus concentration of 4 x 10(20) cm-3, which res ulted from a reduction in the maximum free-energy change for the nucle ation.