Fluctuation model for p–n heterojunction solar cells

Influence of the roughness (microrelief) of an active interface in p–n junction solar cells (SC) on the photovoltage (the open-circuit voltage Voc) has been studied. Nonuniformity of contact potential difference between p- and n-regions leads to barrier height fluctuation that are exponentially enhanced when dealing with barrier current. This results in some decrease of the Voc value. Three theoretical models of averaging open-circuit voltage were used. Experimental results on p+-AlxGa1−xAs/p+-n-GaAs heterostructure SC with various microrelief, obtained by the anisotropic chemical etching, are compared with theoretical calculations.