STRUCTURAL INVESTIGATION OF THE BIAS-ENHANCED NUCLEATION AND GROWTH OF DIAMOND FILMS BY MICROWAVE PLASMA CHEMICAL-VAPOR-DEPOSITION

Transmission electron microscopy (TEM), transmission electron diffract ion (TED), atomic force microscopy (AFM), and scanning electron micros copy have been used to investigate the initial nucleation process and growth behavior of diamond films by microwave plasma chemical vapor de position. TED examination revealed epitaxial relations between the bet a-SiC and the Si, and the diamond and the beta-SiC, which depended on the bias-enhanced nucleation (BEN) time and methane (CH4) concentratio n. The highly oriented (001) diamond films were obtained after 25 min BEN for 4% CH4 and 20 min BEN for 8% CH4. TEM revealed the beta-SiC cr ystallites 2-25 nm across and the diamond crystallites 34-40 nm in siz e, which depended on the CH, concentration and the BEN time. As the BE N time increased, the density of the beta-SiC cyrstallites increased f rom similar to 2.7 x 10(11) to similar to 3.4 x 10(12) cm(2), while th at of the diamond crystallites varied from similar to 2.0 x 10(9) to s imilar to 4.0 x 1(01)0 cm(-2). Discrepancy between the densities obtai ned using TEM and AFM is discussed. It is shown that the heteroepitaxi ally oriented diamond crystallites are critically important for the gr owth of the highly (001)-oriented diamond films, although the heteroep itaxially oriented beta-SiC crystallites could serve as nucleation sit es for the growth of the diamond films.