Microcrystalline and micromorph device improvements through combined plasma and material characterization techniques

Hydrogenated microcrystalline silicon (μc-Si:H) growth by very high frequency plasma-enhanced chemical vapor deposition (VHF-PECVD) is studied in an industrial-type parallel plate KAI reactor. Combined plasma and material characterization techniques allow to assess critical deposition parameters for the fabrication of high quality material. A relation between low intrinsic stress of the deposited i-layer and better performing solar cell devices is identified. Significant solar cell device improvements were achieved based on these findings: high open circuit voltages above 520 mV and fill factors above 74% were obtained for 1 μm thick μc-Si:H single junction cells and a 1.2 cm² micromorph device with 12.3% initial (V_oc=1.33 V, FF=72.4%, J_sc=12.8 mA cm⁻²) and above 10.0% stabilized efficiencies.