The paradox of compensated silicon

Compensated doping is typical of upgraded metallurgical silicon. The relatively low carrier mobility associated to high concentrations of both acceptors and donors leads to paradoxical effects on solar cell performance. While the short-circuit current is expected to decrease compared to non-compensated silicon of the same resistivity, the open-circuit voltage is predicted to increase when bulk recombination is the dominant loss mechanism. On the other hand, surface recombination is predicted to have a greater impact on compensated Si wafers and to result in a lower effective carrier lifetime. These effects are important to understand measurements of compensated Si wafers and devices.