Transition from minority to ambipolar transport in crystalline silicon at high temperatures

The ambipolar diffusion constant in n- and p-type crystalline silicon as a function of the temperature is determined by contactless transient photoconductivity measurements. At room temperature the ambipolar diffusion constant is given by the minority carrier diffusion constant, whereas for temperatures above 430 K significant deviations art observed. This is ascribed to a transition from minority carrier to ambipolar transport. A model is presented to determine the intrinsic carrier density as a function of the temperature from the ambipolar diffusion constant. This experimentally determined intrinsic carrier density is in agreement with the results of Hall-and conductivity measurements and also with a semiempirical model. (C) 1997 Elsevier Science Ltd.