In-Line High-Rate Deposition of Aluminum Onto RISE Solar Cells by Electron Beam Technology

This paper presents results on the contact formation to Rear Interdigitated Single Evaporation Emitter Wrap Through (RISE EWT) solar cells by electron beam high-rate evaporation of aluminum. In stationary depositions water cooled copper crucible and ceramic crucibles were used. The ceramic crucibles were found to be best suitable when regarding the electron beam power and the upper limit of the solar cell temperature of 400 °C. Using an in-line high-rate deposition equipment 20 ?m-thick aluminum layers were deposited at dynamic deposition rates of 3.6 ?m×m/min from ceramic crucibles onto RISE EWT solar cells. The cell temperature during deposition was measured and analyzed using 2-dimensional finite-element (FEM) simulations. The processed RISE EWT solar cells present efficiencies of up to 18.4 %, which equals the cell efficiencies of reference solar cells that are contacted at lower deposition rates at lab scale