Fabrication of Si heterojunction solar cells using P-doped Si nanocrystals embedded in SiN^sub x^ films as emitters

• Published in: Nanoscale research letters 2013-11, Vol.8 (1), p.1
• Main Authors: Wu, Ping-jung, Wang, Yu-cian, Chen, I-chen
• Format: Article
• Language: English
• Subjects: Nanocrystals
• ISSN: 1931-7573; 1556-276X
• DOI: 10.1186/1556-276X-8-457

Si heterojunction solar cells were fabricated on p-type single-crystal Si (sc-Si) substrates using phosphorus-doped Si nanocrystals (Si-NCs) embedded in SiN^sub x^ (Si-NCs/SiN^sub x^) films as emitters. The Si-NCs were formed by post-annealing of silicon-rich silicon nitride films deposited by electron cyclotron resonance chemical vapor deposition. We investigate the influence of the N/Si ratio in the Si-NCs/SiN^sub x^ films on their electrical and optical properties, as well as the photovoltaic properties of the fabricated heterojunction devices. Increasing the nitrogen content enhances the optical gap E^sub 04^ while deteriorating the electrical conductivity of the Si-NCs/SiN^sub x^ film, leading to an increased short-circuit current density and a decreased fill factor of the heterojunction device. These trends could be interpreted by a bi-phase model which describes the Si-NCs/SiN^sub x^ film as a mixture of a high-transparency SiN^sub x^ phase and a low-resistivity Si-NC phase. A preliminary efficiency of 8.6% is achieved for the Si-NCs/sc-Si heterojunction solar cell.