Incorporation of Cl into hydrogenated amorphous silicon without optical band gap widening

Chlorine atoms were introduced into plasma deposited hydrogenated amorphous silicon films by adding HCl to SiH₄ containing discharge. Bulk and surface infrared spectra, film thickness and optical band gap were examined by in situ multiple total internal reflection Fourier transform infrared spectroscopy and spectroscopic ellipsometry. The growing top surface was chlorinated effectively and chlorine was incorporated into the growing film by abstraction and replacement of surface H. Cl concentration in the film is increased at the expense of decreasing H concentration, resulting in films with little optical band gap widening as compared to a-Si:H in spite of containing over 10²¹ cm^-3 chlorine atoms, a concentration that is comparable to that of hydrogen.