Adapted parameterization of incomplete ionization in aluminum-doped silicon and impact on numerical device simulation

The amount of incomplete ionization of aluminum-doped silicon is measured at room temperature by comparing electrochemical capacitance-voltage measurements with micro Raman spectroscopy. It is shown that commonly used parameterizations significantly underestimate the effect of incomplete ionization in Al doped Si. Based on the experimental data, we propose new parameter values for the parameterization of incomplete ionization given in Altermatt et al., J. Appl. Phys. 100, 113715 (2006). Using these new values, the saturation current density J0,pþ of the Al-alloyed region of a standard silicon solar cell is determined by means of numerical device modeling. It is shown that the parameterization influences J0,pþ significantly. Additionally, the weakening effect of incomplete ionization on band gap narrowing (BGN) should be taken into account in modeling that aims to predict device behavior after changes made to the Al-alloyed region.