Deliverable D3.1 - Report on optical and passivation potential of front-side layers developed for front-surface of the IBC device

In this period (M12), both low-temperature (CEA, TUD) and high-temperature (ISFH) passivation approaches are developed. CEA developed very promising a-SiOx:H, nc-SiOx:H and nc-Si:H layers in terms of high i-V_oc (> 750 mV) and low J_o (< 1 fA/cm²), whereas TUD developed aSi:H/SiN_x/SiO_x multi-layer with outstanding effective carrier minority lifetimes (> 24 ms). However, both low-temperature approaches are lacking the desired optical transparency (in other words higher J_sc loss than targeted) due to absorbant a-Si:H layers deposited for chemical passivation. On the other hand, high-temperature passivation approach developed by ISFH showed no absorption loss in the 300-1200 nm range thanks to transparent ALD-grown AlO_x passivation layers, but with lower passivation properties. It is concluded that utilizing AlO_x layers on thinner wafers has the potential to reach the targeted KPIs.