Spatially-separated atomic layer deposition of Al\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e, a new option for high-throughput Si solar cell passivation

\u3cp\u3eA next generation material for Si surface passivation is atomic layer deposited (ALD) Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e. However, conventional time-resolved ALD is limited by its low deposition rate. Initially, a high-deposition-rate prototype ALD reactor based on the spatially-separated ALD principle has been developed, with Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e deposition rates up to 1.2 nm/s. Later, the spatial ALD technique has been transferred to an actual in-line process development tool (PDT) for commercial high-throughput ALD of Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e, resulting in a deposition rate of 30 nm/min. The passivation quality and uniformity of the spatially-separated ALD Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e films are evaluated on p- and n-type Si, applying quasi-steady-state photo-conductance, carrier density imaging and infrared lifetime mapping. In all cases, a spatial ALD Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e layer of only 10 nm reached an excellent passivation quality and uniformity, comparable to reference wafers passivated by equivalent temporal plasma-assisted or thermal ALD Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e. Effective surface recombination velocities as low as 1.1 or 2.9 cm/s were obtained after annealing at 350°C or firing, respectively. Using spatial ALD Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e passivated local Al back surface field p-type Si solar cells, the sufficient passivation of this high-throughput Al \u3csub\u3e2\u3c/sub\u3eO \u3csub\u3e3\u3c/sub\u3e layer is evaluated: an average gain in open circuit voltage as compared to SiO \u3csub\u3ex\u3c/sub\u3e rear passivated i-PERC cells is obtained.\u3c/p\u3