On the Plasma Chemistry During Plasma Enhanced Chemical Vapor Deposition of Microcrystalline Silicon Oxides

The advanced opto-electronic properties of microcrystalline silicon oxide (mu c-SiOx:H) thin film layers deposited by means of plasma enhanced chemical vapor deposition (PECVD) resulted in several applications of this material especially in solar cells and modules in the last years. We investigated the plasma chemistry during the PECVD of mc-SiOx: H using in situ plasma diagnostics. Plasma properties are related to the properties of resulting mc-SiOx: H films measured ex situ. Two different deposition regimes were identified. Besides the standard low pressure regime, a high pressure regime was found, which lead to mu c-SiOx:H layers with high crystallinities and low refractive indices.