Hydrogen content in boron thin films prepared by ECR discharge of decaborane diluted by hydrogen and helium gases

Boron thin films were prepared by electron cyclotron resonance (ECR) discharge in decaborane diluted by helium and hydrogen gases. The hydrogen content C-H Of the films decreased as the substrate temperature T-s increased. The value of C-H was 2 +/- 0.4 at% at T-s = 300 degrees C under various discharge conditions. The content C-H at T-s less than 200 degrees C decreased as the helium gas pressure increased. Spectroscopic observation revealed that the composition of the radical species in the plasmas was one of the factors determining the hydrogen content in the boron thin films prepared by plasma chemical vapour deposition (PCVD). When a bias voltage V-B exceeding 300 V was applied to the substrate, the hydrogen content C-H seems to increase. Bombardment by ions of energy more than 300 V during the deposition enhanced the hydrogen content in the amorphous hydrogenated boron produced by PCVD.