Plasma parameter measurements and deposition of a-Si : H thin films in pulsed ECR plasma.

Pulse modulation of the incident microwave power was investigated for the c ontrol of plasma parameters and improvement of the films deposited in ECR p lasma. Measurements of the temporal variation of plasma parameters in the p ulse-modulated ECR plasma indicate that the electron density varies little in time while the electron temperature decreases rapidly within 10 mus afte r the discharge. The results suggest that pulse modulation where the power- off period is approximately 10 mus enables reduction of the mean electron t emperature while keeping a high electron density. Furthermore, we have prep ared hydrogenated amorphous silicon films by the ECR plasma CVD method. It was found that the ratio of photoconductivity to dark conductivity of the f ilm was improved from 10(3) to 2.5 x 10(5) without heating the substrate an d the deposition rate was 14 Angstrom /s by pulse-modulated ECR plasma. (C) 2000 Elsevier Science B.V. All rights reserved.