Drastic reduction in the surface recombination velocity of crystalline silicon passivated with catalytic chemical vapor deposited SiN_x films by introducing phosphorous catalytic-doped layer

We improve the passivation property of n-type crystalline silicon (c-Si) surface passivated with a catalytic chemical vapor deposited (Cat-CVD) Si nitride (SiN_x) film by inserting a phosphorous (P)-doped layer formed by exposing c-Si surface to P radicals generated by the catalytic cracking of PH_3 molecules (Cat-doping). An extremely low surface recombination velocity (SRV) of 2 cm/s can be achieved for 2.5 Ω cm n-type (100) floating-zone Si wafers passivated with SiN_x/P Cat-doped layers, both prepared in Cat-CVD systems. Compared with the case of only SiN_x passivated layers, SRV decreases from 5 cm/s to 2 cm/s. The decrease in SRV is the result of field effect created by activated P atoms (donors) in a shallow P Cat-doped layer. Annealing process plays an important role in improving the passivation quality of SiN_x films. The outstanding results obtained imply that SiN_x/P Cat-doped layers can be used as promising passivation layers in high-efficiency n-type c-Si solar cells