Passivation mechanism of the high-performance titanium oxide carrier-selective contacts on crystalline silicon studied by spectroscopic ellipsometry

Variable-angle spectroscopic ellipsometry analysis is performed to study the impact of post-deposition annealing on the passivation performance of the heterocontacts consisting of titanium oxide and silicon oxide on crystalline silicon (c-Si) prepared by atomic layer deposition (ALD) for the development of high-performance ALD-TiOx/SiOy/c-Si heterocontacts. The highest lifetime of 1.8 ms is obtained for the TiOx/SiOy/c-Si heterocontacts grown at 175 degrees C after annealing at 275 degrees C for 3 min. With increasing annealing temperature, the TiOx layers of the TiOx/SiOy/c-Si heterocontacts become dominant. Furthermore, the amplitude of dielectric functions of the ALD-TiOx layer decreases as annealing temperature increases, which suggests that enhanced diffusion of Ti into SiOy interlayers at higher annealing temperature. The sufficient diffusion of Ti atoms into SiOy interlayers is caused by annealing at 275 degrees C for 3 min, yielding high-quality interface passivation.

Automated summary

Variable-angle spectroscopic ellipsometry analysis was used to study the impact of post-deposition annealing on the passivation performance of TiOx/SiOy/c-Si heterocontacts. It was found that annealing at specific temperatures can enhance interface passivation and prolong the lifetime.