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solve no. 1
-2- Question 1 Sil'tronix Silicon Technologies has released the product notes of their range of silicon wafers. By referring to the notes: a) Analyse the range of doping concentration for P-type Czochralski silicon wafers and Float Zone silicon wafers, respectively (Hole mobility, un= 450 cm?/Vs). b) Compare results in (a). Provide explanation in terms of their production nature and their applications in electronic devices. c) The product notes show a range of silicon wafer sizes that you can choose starting from 1” to 6" wafers. Despite the sizes of the wafers, a constant wafer resistivity can be achieved. For example, a 1-inch wafer and a 6-inch wafer can both have a resistivity value of 150 Ohm cm. Discuss how this is achieved. (50 marks) (This is an open-ended question. You may make your own assumptions on certain parameters, as long as they are valid. There are more than one answer accepted for this type of question. Hence cheating, plagiarizing and utilizing online tutor are not encouraged as it may result in a significant loss of marks). Question 2 An abrupt silicon P-N junction with doping concentrations of Na = 5 x 1016 cm-and No = 2.5 x 1016 cm 3 respectively is biased at V = 0.8 V. Determine the ideal forward current assuming that the N-type region is much smaller than the minority carrier diffusion length with In = 1 um and assuming a "long” P-type region, sufficiently enough for the minority carriers to diffuse in. Use Me = 1450 cm?/Vs, un = 500 cm2/s and intrinsic concentration of 1010 cm-3 in your calculations. The minority carrier lifetime in P-type is given as 10 us and the height of the structure = width of the structure = 100 um. Discuss what happens to the forward current when the voltage is increased even further under same temperature environment. Will the saturation current also change? (50 marks)