Study on the Passivation of Si Surface by Incorporation of Nitrogen in Al2O3Thin Films Grown by Atomic Layer Deposition

To improve the efficiency of the Si solar cell, high minority carrier life time is required. Therefore, the passivation technology is important to eliminate point defects on the silicon surface, causing the loss of minority carrier recombination. PECVD or post-annealing of thermally-grown SiO2 is commonly used to form the passivation layer, but a high-temperature process and low thermal stability is a critical factor of low minority carrier lifetime. In this study, atomic layer deposition was used to grow the Al2O3 passivation layer at low temperature process. Al2O3 was selected as a passivation layer which has a low surface recombination velocity because of the fixed charge density. For the high charge density, an improved minority carrier lifetime, and a low surface recombination, nitrogen was doped in the Al2O3 thin film and the improvement of passivation was studied.