METHOD FOR PRODUCING PHOTOVOLTAIC-GRADE CRYSTALLINE SILICON BY ADDITION OF DOPING IMPURITIES AND PHOTOVOLTAIC CELL

摘要

Production of photovoltaic grade crystalline silicon is achieved by crystallization of a molten silicon feedstock, the sum of the initial donor doping element and acceptor doping element concentrations whereof is greater than 0.1 ppma, and both the acceptor and donor doping element concentrations whereof are less than 25 ppma. At least a predefined quantity of a doping material having a segregation coefficient of less than 0.1 is added to the feedstock. This addition enables a crystallized silicon to be produced the difference between the donor and acceptor doping profiles whereof is comprised between 0.1 and 5 ppma over at least 50% of the solidified silicon. A silicon presenting a concentration of at least one of the dopants is greater than or equal to 5 ppma and a difference less than or equal to 5 ppma between these two types of dopant is integrated in a photovoltaic cell.