CHEMICAL BONDING IN THIN GE/C FILMS DEPOSITED FROM TETRAETHYLGERMANIUM IN AN RF GLOW-DISCHARGE - AN FTIR STUDY

Fourier transform infrared spectra of a series of Ge/C films deposited from tetraethylgermanium in a radio frequency (r.f.) glow discharge under variable r.f. power (in the range 2-100 W) are presented. It is shown that IR absorption of the films varies dramatically depending on the r.f, power. Various C-H bands as well as strong Ge-O absorption (not present in the monomer) are characteristic for samples produced at low power input. Films deposited at high r.f. power conditions are characterised by a lack of Ge-O signals, considerable Ge-H absorption and substantial broadening of all bands. A mechanistic interpretation, based on the postulated formation of germanium dangling bonds, is given to explain the competition between the formation of Ge-O and Ge-H bonds under different energetic conditions.