Investigation of P-type Hydrogenated Nanocrystalline Silicon Grown by VHF-PECVD as Emitter in Silicon Heterojunction Solar Cells

Abstract

P-type hydrogenated nanocrystalline silicon (ncSi: H(p)) films as emitter layers in silicon heterojunction solar (SHJ) cells by VHF-PECVD (65 and 100 MHz) and standard RF-PECVD (13.56 MHz) were investigated. We demonstrate that the use of VHF-PECVD is advantageous in fast nucleation in a very thin layer (< 15 nm), which in turn results in improved TCO/p contact. In addition, the deposition of nc-Si: H (p) layer by VHF-PECVD can improve the surface passivation properties as evidenced by QSSPC lifetime measurement for the solar cell precursor (i. e., pi/ c-Si/ in). These results suggest that VHF plasma generates more atomic hydrogen flux, which brings beneficial aspects both in terms of nc-Si: H growth and post-hydrogenation. Compared to our standard a-Si: H(p) emitter, the use of nc-Si: H(p) prepared by 65 MHz PECVD improved the efficiency from 19.59% to 20.50%.