If the densities of free minority and majority carriers have a reverse dependence on the Auger recombination enhancement factor, g, and minority-carrier diffusivity has a direct dependence on g, then the minority-carrier transport equations in non-uniformly doped Si regions in the dark can be solved analytically for the case, where lifetime is only determined by Auger recombination, and two new analytical expressions for saturation current density of emitter, J 0em, can be derived, one in p-type Si and the other in n-type Si, by imposing boundary conditions including band-gap narrowing (BGN). The new expressions include the integral of emitter doping profile. We calculate curves of majority-carrier mobility versus doping by taking into account BGN and find that majority- and minority-carrier diffusivity of same carrier species can be assigned the same direct dependence on g. The integral of doping profile can be consequently expressed as a function of sheet resistance and the new expressions for J 0em can be calculated without necessarily knowing the emitter doping profile. The assumption on diffusivities holds at room temperature for dopings higher than 6 ×1017 cm-3 in both p- and n-type Si. The new J 0em-expressions are used to characterize actual reported n + and p + metal-coated and n + passivated emitters with respect to surface doping, diffusion depth, sheet resistance, and surface recombination velocity.
|Titolo:||Exact analytical expressions for Auger saturation current in diffused Si emitters|
|Data di pubblicazione:||2019|
|Appare nelle tipologie:||1.1 Articolo in rivista|