ECN publication
Large area deposition of microcrystalline silicon by microwave PECVD
Löffler, J.; Muffler, H.J.; Devilee, C.; Gajovic, A.; Dubcek, P.; Gracin, D.; Soppe, W.J.
Published by: Publication date:
ECN Solar Energy 1-9-2005
ECN report number: Document type:
ECN-RX--05-150 Conference Paper
Number of pages: Full text:
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Presented at: 21st International Conference on Amorphous and Nanocrystalline Semiconductors - ICANS 21, Lisbon, Portugal, 5-9 september 2005.


Intrinsic microcrystalline and amorphous silicon layers have been deposited by Microwave PECVD on glass substrates under variation of the silane to hydrogen ratio. A series of samples deposited at higher total pressure and with lower microwave power than previously applied is presented. The plasma was studied by means of optical emission spectroscopy. With increasing silane fraction, the silane utilization as well as the Há/SiH* ratio in the plasma decrease, and the layers become more amorphous. The hydrogen content in the film and the refractive index of the material at 0.5 eV, an indicator for the density of the films, increase with increasing silane fraction. The higher total pressure and lower microwave power during deposition resulted in a strong improvement in the structural and opto-electrical properties of microcrystalline and amorphous silicon layers. The best amorphous layers have ódark of 6*10-10 S/cm, óphdark of 6*104,  R* below 0.1, and an Urbach tail Energy of 55 meV. For the microcrystalline layers close to the ìc-Si/a-Si transition, ódark of 1*10-6 S/cm,  óphdark of 16, and an Urbach tail Energy of 107 meV have been achieved.

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