Question

You are considering options for a deposition process for a-Si that gives acceptable quality films and is able to deposit 5 nm thickness in less than a minute. Compare the HW PECVD, VHF PECVD and RFCVD in terms of the required output.

Answer 1

Plasma Enhanced Chemical Vapor Deposition (PECVD) is a process by which thin films of various materials can be deposited on substrates at lower temperature than that of standard Chemical Vapor Deposition (CVD).

The development of an adapted p-layer is crucial for microcrystalline solar cells. The p-layer has to fulfil many requirements: Together with the n-layer it has to build up the electric field. The absorbance has to be low because the cell is illuminated from the p-side and because due to the low diffusion length in doped /c-Si :H the light absorbed in the p-layer is mostly lost for the solar cell .

Usually microcrystalline p-layers are prepared by VHF (very high frequency) deposition [104,105] which is known to favor Mc-Si:H growth. A VHF deposition process for /c-Si:H p-layers was already available at the PECVD system applied in this work.

Here is Comparison of RF and VHF (110 MHz) deposition regime for microcrystalline players (Si)