ANALYSIS OF HYDROGEN IN LOW-PRESSURE DIAMOND LAYERS

The hydrogen concentration of diamond layers produced by a low pressure chemical vapour deposition method on SiAlON substrates has been determined by means of the N-15 nuclear reaction analysis technique. The results show distinct differences in the hydrogen content which depend on the gas pressure and on the acetone-hydrogen gas mixture used in the deposition. The resulting diamond morphology is found to be related to the hydrogen content, well-faceted layers containing about 0.2-0.9 at.% H, and balas-type layers with about 1.4 at.% H. Contrary to expection, no relation between the crystal size in the well-faceted layers and the average hydrogen content was found. Additional Rutherford backscattering measurements revealed a high purity of the films with respect to elements heavier than carbon.