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Unformatted text preview: I313 331 Midterm #1 Page is W
Eli331 Devices and Circuits i Instructor: Tai~Chang Chen Midterm #1
10:30 — 11:20pm 10/24/2008 Friday Name: SDWCRQ q Student Number:
W Notes: 1. This exam is closed book, closed notes, closed homework and homework solutions. You are
permitted one 8.5” x 11” doublesided sheet of summary notes. 2. Try to ﬁt your work onto the same sheet as the problem itself. If you need to include
additional sheets, place these immediately behind the sheet that the problem is on. 3. Partial credit will be based upon how well you describe what you are doing.
4. Answers with no units, when applicable, will receive zero credit. 5. Good luck! Problem 1: Intrinsic carrier concentration calculation (25 points) In a Borondoped silicon layer with impurity concentration of 1016 /cm3, ﬁnd the hole and
electron concentrations at 25°C and 125°C. Ito _
Npﬁ‘lb cmg; 4w. batM Tamra. 25°C£2629tq and. {:L‘iQC. name). ER 331 Midterm #1 Page /5 Problem 2: Diffusion current analysis (2/0 points) Holes are being steadily injected into a region of n—type silicon (connected to other devices, the
details of which are not important for this question). In the steadily state, the excess—hole
concentration proﬁle shown below is established in. the n—type silicon region. Here “excess”
means over and above the concentration Pm. H'ND = 1.0 x 1016 cm'3, ni : 1010 cm's, up = 450
cmles, and W: 5 pm. Find the current density that will ﬂow in the x direction. Pn(x) Z 1000Pn0 _. hi _ lb  D4 '3 .
n region ho n i 0 {9 i C. M 15;;
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JP‘”%DPW 9‘” DP WM 2 otolggxatts‘ozuh BB 331 Midterm #1 Page is {m ”‘1‘ . Problem 3: Depletion layer analysis (2'36 points) A junction in which p and n are doped equally with 1016 cm'3.
Assume ni = 1.010 cm'3 . With no external voltage applied. The crosssection area is 100 um‘z. Find (a) the built—in voltage; (’0) the width of depletion region in pm; (0) the junction capacitance
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We; 0 745 VIC—4' 00K (0 Problem 4. Diode Circuit Analysis: (25 points) Assuming that the diodes in the circuits are ideal, determine the diode states (ON or OFF)
and ﬁnd the value of voltages (V). 2.0%“ 20K 7 lDKD. [26W _ D " "1 0.4—5
Zbl4 =45" l m,” .,__ lfoihts Possible“! Your Score
Problem} 25 Problem” 1 25
Problem 3 25 Problem 4 455,25? m L Exam Soore 190 ...
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 Spring '08
 Taicheng

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