Technology Outline (Process Description)

Developed an industry−friendly process for fabricating Silicon heterojunction (SHJ) solar cells. The SHJ solar cell involves an intrinsic hydrogenated amorphous silicon (a−Si:H) thin film on a c−Si wafer, followed by a doped a− Si:H emitter layer. We employ a low−temperature process for the fabrication reducing the thermal budget. All the amorphous silicon layers are deposited using the HWCVD technique. To realize these SHJ solar cells on a 6”x6” area with a simplified processing steps, we designed and constructed an indigenous multi−chamber fabrication tool employing HWCVD (a low−cost processing technology). This tool comprises a load−lock, substrate transfer chamber, and separate reactors for depositing individual intrinsic and doped silicon films. It also comprises an RF sputter reactor for transparent conducting oxide (TCO) or metal deposition. Since cell fabrication does not incorporate sophisticated steps such as photolithography, its upscaling for industry integration will prove significantly easier.