Investigation on the passivated Si/Al(2)O(3) interface fabricated by non-vacuum spatial atomic layer deposition system

Currently, aluminum oxide stacked with silicon nitride (Al(2)O(3)/SiN(x):H) is a promising rear passivation material for high-efficiency P-type passivated emitter and rear cell (PERC). It has been indicated that atomic layer deposition system (ALD) is much more suitable to prepare high-quality Al(2)O(3) films than plasma-enhanced chemical vapor deposition system and other process techniques. In this study, an ultrafast, non-vacuum spatial ALD with the deposition rate of around 10 nm/min, developed by our group, is hired to deposit Al(2)O(3) films. Upon post-annealing for the Al(2)O(3) films, the unwanted delamination, regarded as blisters, was found by an optical microscope. This may lead to a worse contact within the Si/Al(2)O(3) interface, deteriorating the passivation quality. Thin stoichiometric silicon dioxide films prepared on the Si surface prior to Al(2)O(3) fabrication effectively reduce a considerable amount of blisters. The residual blisters can be further out-gassed when the Al(2)O(3) films are thinned to 8 nm and annealed above 650°C. Eventually, the entire PERC with the improved triple-layer SiO(2)/Al(2)O(3)/SiN(x):H stacked passivation film has an obvious gain in open-circuit voltage (V(oc)) and short-circuit current (J(sc)) because of the increased minority carrier lifetime and internal rear-side reflectance, respectively. The electrical performance of the optimized PERC with the V(oc) of 0.647 V, J(sc) of 38.2 mA/cm(2), fill factor of 0.776, and the efficiency of 19.18% can be achieved.