Effectively surface-passivated aluminium-doped p(+) emitters for n-type silicon solar cells

We present a detailed study on surface passivated screen-printed aluminium-alloyed emitters, for back junction n-type silicon solar cells. We investigated (i) two-different commercially available aluminium pastes and (ii) two passivation layers both well suited for highly doped p silicon plasma-enhanced chemical-vapor-deposited amorphous silicon (a-Si) and atomic-layer-deposited aluminium oxide (Al2O3). We show that for the formation of a homogenous non-shutnted emitter, a careful choice of the alooying conditions is essential. Moreover, for a most effective surface passivation low emitter thicknesses have to be used. Combing, these two aspects, we have achieved extraordinary high implied open-circuti voltages of 673 mV for a-Si- and 685 mV for Al2O3-passiaved Al-alloed emittes, corresponding to emitter stauration current densites of 128 and 55 fA/cm(2,) respectively.