Influence of the dopant compensation on the silicon electronic properties and on the performances of solar grade silicon solar cells
This study aims at understanding the influence of the dopant compensation on the performances of solar cells based on solar-grade silicon purified via metallurgical routes. We first detailed the physics of compensated semiconductors. The compensation effects were then studied at the wafer level. We found a sharp unpredicted reduction in carrier mobility at high compensation level. Conversely, the dopant compensation was shown to be very beneficial to the carrier lifetime. We specified the recombination properties of dopants. We then focused on the compensation effects at the solar cell level. We obtained conversion efficiencies of 16% on highly doped and compensated solar cells, revealing the photovoltaic potential of solar-grade silicon. Since numerous association reactions occur between dopants and defects, we built an algorithm in order to simulate the association kinetics of such reactions. Eventually, we presented two innovative characterisation techniques that allow the concentrations of dopants and light elements to be measured.