SOLUTION: IME 2009 Microelectronics 2 | My Assignment Tutor

YSGOL CYFRIFIADUREG A PHEIRIANNEG ELECTRONIGSCHOOL OF COMPUTER SCIENCE AND ELECTRONIC ENGINEERINGArholiadau Diwedd Semester 2End of Semester 2 Examinations2019/2020IME 2009Microelectronics 2Amser a ganiateir: 1½ awrTime allowed: 1½ hoursCyfarwyddiadau / Instructions:Answer all questionsTotal marks 100Trowch y dudalen drosodd pan ddywedir wrthych / Please turn over when instructed2IME 2009 Microelectronics 2Physical constants:Electronic charge, e = 1.6×10-19 CPermittivity of free space, ε0 = 8.85×10-12 F m-1Boltzmann’s constant, k = 1.38×10-23 J K-1 = 8.62×10-5 eV K-11. The three important sources of electrical current in semiconductor devices are (i) drift (ii)diffusion (iii) generation-recombination. Explain the origin of each source of current andprovide examples of where such currents may be encountered in electronic devices. [18]2. After illumination, the excess minority hole concentration, ∆p, in n-type silicon change withtime following the relationWith h is the minority carrier life time and GL is the hole generation rate due to light. Calculatehow long after switching on the light, ∆p reaches 50% of its final value. You may assume thath = 100 μs. [10]3. a) Draw a diagram showing the experimental set-up used in the Haynes-Shockley experiment.Explain how the experiment works and what it measures [10]b) A bar of n-type silicon is investigated using Haynes-Shockley and the Hall effectexperiments. The Haynes-Shockley experiment gives a value of 0.19 m2V-1s-1 carrier mobility,while the Hall effect gives a value of 0.39 m2V-1s-1 for the carrier mobility. Explain thisdifference. [8]4. Explain what type of p-n junction represented in Figure 4.1? With the aid of suitable diagrams,show the charge distributions and voltage drop in a semiconductor when such a p-n junction isformed. [10]Figure 4.1[ exp( )]hL htp G =  1- –35. The total voltage (Vt) across the depletion region for a one sided diode (p+n) is given by:?? =? ??2 ? ???2?Where Nd is the donor concentration in the n-type side of the diode, dn is the depletion length inthe n-type side of the diode, and ε is the permittivity of the semiconductor. If the dopingdensities on the p+ and n sides of the junction are 5 x 1024 m-3 and 2 x 1020 m-3 respectively,estimate the voltage (V) at which punch through will occur. You may assume that the built inpotential is 0.6 V, the total width of the n-type side is 5 µm and the relative permittivity of thesemiconductor is 11.8. [10]6. Explain with the aid of suitable diagrams the four operating modes of a pnp bipolar junctiontransistor (BJT) [16]7. Using appropriate diagrams, explain the processes known as accumulation, depletion, andinversion that can occur at the surface of p-type semiconductor. [18]