Excellent silicon surface passivation using dimethylaluminium chloride as Al source for atomic layer deposited Al2O3

We demonstrate that the surface passivation of crystalline silicon and thermal stability of atomic layer deposited (ALD) Al2O3 can be substantially improved by replacing the conventional aluminium precursor trimethylaluminium (TMA) with low-cost dimethylaluminium chloride (DMACl). A film thickness as low as 6nm is enough to result in a minority carrier lifetime above 1ms after high temperature firing step. In addition, optimal ALD DMACl+H2O process temperature and the film growth rate are comparable to the conventional TMA-based process. Thus, DMACl appears to be a potential alternative precursor for mass production with much lower chemical cost and yet excellent passivation performance.