Industrial production of amorphous silicon solar cells, photoreceptors and several opto-electronic devices requires large area, high-deposition-rate plasma reactors and deposition processes. Non-uniformity of die film thickness and particle generation at high power densities as well as the deposition rate are found to be important limiting factors in large area PECVD.
The deposition was performed in a capacitively-coupled coaxial diode rf glow discharge with large areas (1000 cm2 and 2000 cm2) at 13.56 MHz and 27.12 MHz. We studied the particle generation in the plasma reactor over a wide range of silane concentration (20 % to 100 %) in the SiH4/He mixture. We will present the opto-electronic properties of a-Si:H films and the influence of the substrate bias. The films are characterized by dark- and photoconductivity and by PDS.
It was confirmed through this study that helium dilution is effective in the suppression of powder growth for high-rate deposition up to 18 μm/hr. Special attention was paid to the optimization of reactor design and plasma conditions for the deposition of low density of states a-Si:H (∼1016 cm−3) at deposition rates of up to 18 μm/hr. Darkconductivity was 10−9 S/cm and photoconductivity was about 5.10−4 S/cm.