Transistor & semi conductor device fundamentals

Final Exam, ECE 448- Spring 2022, UIC Name:

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Final Exam, ECE 448 Transistors - Spring 2022 University of Illinois at Chicago

10:30 am to 12:30 pm on May 03, 2022

Name: UIN:

[30 points] PROBLEM # 1 Assume a hypothetical pn junction with the doping profile shown below, derive the expression for the depletion width and the electric field under equilibrium conditions (Note “a” is negative)

Final Exam, ECE 448- Spring 2022, UIC Name:

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[30 points] PROBLEM # 2 In a silicon MOS capacitor with an n-type substrate and a p + polysilicon gate (Ef = Ev), the substrate doping is uniform with Nd = 2 × 1018 cm−3. The oxide thickness is 3 nm. There is a p + channel contact biased at -1V relative to the substrate. The voltage drop across the oxide is Vox = −0.6 V. (a) Determine the state of the channel region (accumulation, flat-band, depletion, strong inversion, etc.). (b) Determine the applied gate voltage. (c) Sketch the charge density, electric field and energy band diagram for the system.

Final Exam, ECE 448- Spring 2022, UIC Name:

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[20 points] PROBLEM # 3 Calculate the base transit time in a npn transistor with NDE= 1019 cm-3, NAB = 1017 cm-3, VBE= 0.8V and a neutral basewidth W = 0.8 μm. Assume DnB= 18 cm2 s-1 and independent of position.

Final Exam, ECE 448- Spring 2022, UIC Name:

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[20 points] PROBLEM # 4 List the steps needed for fabricating an n-MOSFET device. Draw figures to illustrate your response clearly.