Transparent silicon carbide/tunnel SiO2 passivation for c‐Si solar cell front side: Enabling Jsc > 42 mA/cm2 and iVoc of 742 mV. (16th January 2020) - Pomaska, Manuel
Abstract: N‐type microcrystalline silicon carbide (μc‐SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c‐Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc‐SiC:H(n) for c‐Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc‐SiC:H(n) on tunnel oxide (SiO2 )–passivated c‐Si with an implied open‐circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm 2 . This excellent passivation quality is achieved directly after the HWCVD deposition of μc‐SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF2 )/silicon nitride (SiNx :H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm 2 with MgF2 /SiNx :H/μc‐SiC:H(n) and 0.62 mA/cm 2 with MgF2 /μc‐SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF2 /μc‐SiC:H(n)/SiO2 /c‐Si as front side layer stack in an IBC solar cell reveal a short‐circuit current density of 42.2 mA/cm 2, an open‐circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%. Abstract : N‐type microcrystalline silicon carbide on tunnel oxide passivates c‐Si with an i V oc of 742 mV, which is achieved directly after the HWCVD deposition of silicon carbide at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Calculations with Sentaurus TCAD simulation where the transparent passivating contact used as antireflection coating in an IBC solar cell reveal a J sc of 42.2 mA/cm 2, a V oc of 738 mV, an FF of 85.2%, and a maximum conversion efficiency of 26.6%.