Question Detail

Let's evaluate each statement:A. Doping involves adding impurities to intrinsic (pure) semiconductors, which increases the concentration of either electrons or holes, thereby altering the balance of charge carriers. This statement is TRUE.B. By increasing the number of charge carriers (electrons or holes), doping significantly increases the conductivity of semiconductors. This statement is TRUE.C. Semiconductors, whether intrinsic or doped, are highly sensitive to temperature. Their conductivity increases with increasing temperature due to more thermal energy freeing carriers. Thus, doped materials are NOT immune to temperature effects. This statement is FALSE.D. In extrinsic (doped) semiconductors, electrons and holes are the primary charge carriers. Due to their different effective masses and interaction with the crystal lattice, electrons and holes generally have different mobilities and thus travel at different average speeds under the influence of an electric field. Therefore, they do NOT travel with the same speed. This statement is FALSE.The question asks for what is 'not true'. Both C and D are not true. However, the option D, 'carriers travel with the same speed in extrinsic materials', is a more direct and universally false statement regarding the properties of charge carriers, as electrons and holes inherently have different mobilities. While semiconductors are indeed affected by temperature, stating they are 'immune' is also false, but different carrier speeds is a fundamental property.