NeoGrowth silicon: A new high purity, low-oxygen crystal growth technique for photovoltaic substrates

SolarWorld has developed a new entrant in the field of crystal growth for silicon photovoltaic substrates. The NeoGrowth technique is a contactless bulk crystal growth method for producing single crystal ingots. NeoGrowth material can be produced at a throughput on par with G5 multicrystalline silicon, but with p-type as-grown minority carrier lifetimes exceeding 600 microseconds for a 1.5-ohm cm resistivity. The silicon has low oxygen, and light-induced degradation is measured at 0.5% to 0.7% in passivated emitter rear contact–based modules. In the first report of results from this technique, p-type resistivity can be managed within a range of 1.5 to 2.0 ohm cm over the entire ingot. Dislocation density is shown to be typically in the 10⁴ to 10⁵/cm² range but can be managed down to even lower levels. After cell processing steps, minority carrier lifetime can exceed 1.5 milliseconds for p-type material and cell efficiencies on industrial cells range up to 20.9%.