372596249

RIKEN Accel. Próg. Rep. 24 (1990)

111-3-17. Hydrogen Desorption from Diamond-like Carbon Film during

lon Beam Irradiation

M. Minami, M. Aratani, and M. Yanokura

In measuring hydrogen contents in diamond-like carbon (DLC) films by elastic recoil detection analysis, we observed a decrease in hydrogen contents with the irradiation time.

The DLC films (about 200 nm thick) were pre-pared from methane on Silicon wafers by the elec-tron cyclotron resonance (ECR) Chemical vapor deposition (CVD) method. The size of each film was 20 mm x 10 mm.

The scattering chamber (100 cm in diameter, 2 x 10 '⁶ Torr) located at the RILAC A-l beam linę was employed. At the center of the chamber, the DLC films were set up at 30° to a 50 MeV incident argon beam of 2 nA. Two surface barrier semicon-ductor detectors (SSD) were arranged at 35° (SSD-1) and at 50° (SSD-2) to the beam. In front of the SSD-1, an aluminium foil (10 m thick) was set up to detect only hydrogen and carbon ions in the specimens.

Figurę 1 shows the decrease in hydrogen con-tent of the DLC film during ion-beam irradiation; no such a decrease was observed for hydrogenated amorphous Silicon (a-Si:H) films.^l) The preparation methods for the DLC and a-Si:H films are very similar in Chemical forms of starting materials and decomposition processes. Starting gas was CH₄ for the DLC films and SiH₄ for the a-Si: H films.

The decrease in hydrogen content may be con-

Fig. 1. Hydrogen desorption from DLC film during ion-beam irradiation.

sidered due to the temperaturę rise in the film resulting from energy deposited by heavy ions. Temperaturę measurements, however, suggested no desorption of hydrogen.²⁾ Thus, it could be con-sidered that hydrogen behaves in the DLC films very differently from that in the a-Si:H films. This interesting phenomenon is should be further inves-tigated.

References

1) M. Aratani and T. Nozaki: Unpublished data.

2) K. Yano, H. Oyama, M. Yanokura, M. Aratani, and M. Minami: This Report, p. 64.