Answer Happy

ASSIGNMENT No. 10 Q1. a. Detail the assumptions made in deriving the current-voltage output characteristics for an ideal bipolar junction transistor. b. A common emitter n* -p-n transistor is operated at a collector current of 1mA, base current 20μA and collector base leakage current of InA. If the recombination time for electrons and holes in the base is 0.2μs, estimate i. ii. 111. iv. Emitter current gain, he Leakage current, ICEO Transit time of electrons across base, te Excess base charge, 9B Q2. a. Diffusion and ion implantation are two key processes used to introduce controlled amounts of dopants into semiconductors. i. ii. Describe the doping processes of diffusion and ion implantation Why is silicon used as an effective mask against impurities during the fabricating or manufacturing of IC's when the raw material is silicon? b. Boron is adopant for converting pure silicon to an extrinsic semiconductor. For boron atoms to diffuse into silicon, the temperature is maintained at 1000°C, the concentration of boron at the surface of silicon is maintained at 10¹⁰ cm³ and time for the diffusion process is 1 hour. The total number of dopant atoms per unit area (Q(t)) in a diffused semiconductor is given by the expression Q(t)=1.13C √Dt, where C, is the surface concentration of dopants, D is the diffusivity of the dopants in silicon and t is the time of diffusion. Given that the diffusion coefficient of boron 2x10¹ cm²s", find i. ii. the diffusion length of boron in silicon total number of dopant atoms per unit area in silicon