Improvement of Rear Surface Passivation Quality in p-Type Silicon Heterojunction Solar Cells Using Boron-Doped Microcrystalline Silicon Oxide

Boron-doped microcrystalline silicon oxide (µc-SiO x :H) films for application as a back surface field (BSF) in p-type silicon heterojunction (SHJ) solar cells have been characterized. We found that the µc-SiO x :H(p) film at the optimized condition shows high conductivity and good passivation effect with a low surface recombination velocity of around 10 2 cm/s. However, too much oxygen atoms in the films increase the defect and the passivation quality degrades. Thus, the control of oxygen content in the films is very important to obtain a high passivation quality. With applying the µc-SiO x :H(p) as a BSF layer leads to improved p-type SHJ solar cells performance, which shows the enchantment of EQE spectra in long wavelengths between 800 and 1200 nm. The highest efficiency of the p-type SHJ solar cell we obtain is 18.5% (active area = 0.88 cm 2 ) with a V oc = 659 mV, J sc = 34.7 mA/cm 2 , and FF= 80.9%.