THE INFLUENCE OF DRIFT FIELDS IN THIN SILICON SOLAR-CELLS

The influence of electric ''drift'' fields in the base of silicon sola r cells on device performance is investigated. The drift fields are th e result of a nonuniform dopant density in the base material. Numerica l modelling is carried out for a range of representative cell structur es and two different models for the dependence of the minority carrier lifetime on the dopant density. The cell design variables, in particu lar the dopant densities and the thicknesses of the device regions, ar e optimized with respect to the cell efficiency. Comparison of optimiz ed cells incorporating a drift field with those not having a drift fie ld, shows that a drift field can offer only small efficiency advantage s for particular cell structures and recombination parameters, and onl y if large variations in dopant concentration can be achieved.