(a) A Si crystal is doped homogeneously with Na=X × 10'" phosphorous atoms per cm³ and Na=Y x1014 boron atoms per cm². Assume that at room temperature, all dopants are

ionised, the semiconductoris non-degenerate and the intrinsic carrier concentration n¡= 100/ cm. Using the law of mass action: i) Calculate the free electron carrier concentration. ii) Calculate the free hole carrier concentration. (b) Considering the semiconductor doped as in part (a) above, i) Sketch the energy band diagram, indicating the Fermi level (not to scale) ii) Sketch the energy bands when a voltage of +1V is applied across the semiconductor. Indicate the direction of electron and hole flow. iii) Show the direction of conventional current flow in your band diagram. Will it be a drift or diffusion current?