Silicon Hetero Junction Solar Cells by Hot-Wire CVD

Qi Wang, M. R. Page, E. Iwaniczko, Y. Q. Xu, L. Roybal, R. Bauer, D. Levi, Y. F. Yan, D. Meier, T. H. Wang, H. M. Branz

Research output: Contribution to conferencePaperpeer-review

2 Scopus Citations


We are reporting high performance silicon heterojuncton (SHJ) solar cells fabricated using the hot-wire chemical vapor deposition (HWCVD) technique. On p-type c-Si float-zone wafers, we used an amorphous n/i contact to the top surface and an i/p contact to the back surface to obtain an open circuit voltage (Voc) of 0.67 V in a 1 cm2 cell with an independent confirmed efficiency of 18.2%. This is the best reported p-type SHJ solar cell, at least by HWCVD. On n-type c-Si float-zone wafers, we used an amorphous (p/i) front emitter and an a-Si:H (i/n) back contact to achieve a Voc of 0.69 V on 1 cm2 cell. We found that proper c-Si surface cleaning prior to the amorphous Si deposition and double-heterojunction is a key to the high Voc. In the heterojunction region, an abrupt interface from c-Si to a-Si:H results in a high Voc; while incorporating a transition to either microcrystalline or epitaxial Si at the c-Si interface results in a low Voc. Lifetime measurement shows that the back surface recombination velocity can be reduced to ∼15 cm/s through a-Si:H passivation. Amorphous silicon heterojunction layers on crystalline wafers thus combine low-surface recombination velocity with excellent carrier extraction. The advantages of using HWCVD in comparing with plasma-enhanced CVD are the fast deposition rate and, more important, a wide range of deposition parameters enabling formation of an effective heterojunction with high Voc. Further, the heterojuction cell processing is entirely below 200°C making it one of the few promising low-stress methods for the manufacturing of next generation ultra-thin Si wafer solar cells.

Original languageAmerican English
Number of pages4
StatePublished - 2007
EventInternational Solar Energy Society Solar World Congress 2007, ISES 2007 - Beijing, China
Duration: 18 Sep 200721 Sep 2007


ConferenceInternational Solar Energy Society Solar World Congress 2007, ISES 2007

NREL Publication Number

  • NREL/CP-520-42277


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