Photoinjection into plasma-polymerised thin organosilicon films. II. The structure of energy levels

For pt.I see ibid., vol.14, p.1877 (1981). Studies of the photoinjection of carriers from metal into plasma-polymerised organosilicon films, optical investigations and the results of conductivity measurements, are used to describe the energy band structures of the bulk and surface of these films. Also discussed is the structure of the organosilicon glass-metal contact. The parameters determined include transport gap E_g (=6.3 eV), optical gap E_g^opt (=3.1 eV for aged and untreated films), electron affinity X (=0.7 eV), ionisation potential J(=7.0 eV), bulk worn-function W_i(=6.35 eV) and surface work-function W_s (=4.1 eV for the case of high surface state density). The results obtained indicate that the basic molecular structure of organosilicon films is of the types Si_xC_y:H in spite of differences in the chemical constitution of the compounds used in plasma polymerisation. It is found that in the transport gap there are localised states which are inhomogeneously distributed in the film thickness. These states are probably connected with free spins.