Phosphorous-Doped Silicon Carbide as Front-Side Full-Area Passivating Contact for Double-Side Contacted c-Si Solar Cells

We present an electron selective passivating contact based on a tunneling SiOx capped with a phosphorous doped siliconcarbideandpreparedwithahigh-temperaturethermalanneal. We investigate in detail the effects of the preparation conditions of theSiCx(n)(i.e.,gasflowprecursorandannealingtemperature)on the interface recombination rate, dopant in-diffusion, and optical properties using test structures and solar cells. On test structures, our investigation reveals that the samples annealed at temperatures of 800–850 °C exhibit an increased surface passivation toward higher gas flow ratio (r = CH4/(SiH4 + CH4)). On textured and planar samples, we obtained best implied open-circuit voltages (i-VOC) of 737 and 746 mV, respectively, with corresponding dark saturation current densities (J0) of∼8 and∼4 fA/cm2. The SiCx(n)layerswithdifferentrvalueswereappliedonthetextured front side of p-type c-Si solar cells in combination with a borondoped SiCx(p) as rear hole selective passivating contact. Our cell results show a tradeoff between VOC and short-circuit current density (JSC) dictated by the C-content in the front-side SiCx(n). On p-type wafers, best VOC = 706 mV, FF = 80.2%, and JSC = 38.0 mA/cm2 with a final conversion efficiency of 21.5% are demonstrated for 2 × 2 cm 2 screen-printed cells, with a simple and patterning-free process based on plasma depositions and one annealing step 800 °C < T < 850 °C for the formation of both passivating contacts.