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**Unformatted text preview: **E15 306 F07A MIDTERM EXAM #1 Braun
CLOSED BOOK + 1/2 Cheat Sheet State any assumptions and show all work. Part 1 (16 Pornts)
Part 2 (20 Pomts) (1 point) Print Your Name: 504 6/ 775”; Part 2 (12 Points)
" Total (50 Points) No unauthorized help given or received. I will not discuss this exam
with another human being until after 1 1:00 am today. (1 point) Signature: ééfﬂﬁ For today’s exam, assume for Silicon at room temperature an intrinsic carrier concentration, n, = 1010 cm'3.
1. Semiconductor Fundamentals and PN Junction Diode Consider a PN junction formed between an n-type region of Silicon doped with a donor concentration of
1x1018 cm'3 and a p—type region of Silicon doped with an acceptor concentration of 1x1019 cm‘3.
Please determine the values of the following quantities at room temperature with VT: 0.025 V. (3 points) A) The total depletion-layer width at zero bias. 00 pm?‘ c‘ 29/1/52". 201.7,! 5.3900 F/cw) _ 26: .I. .4 " /
W” 'V/ 7 (44: We)? W 175"" Cover “7791/ = 0.037540" 5 555311149 (3 points) B) The depletion—layer width on the P side of the junction at zero bias. / H W10 3 723,14”:
:- _____..’——~ 1' 3 m
XF l + W, [7- m”:»r3 3' 3? 51
11/0 /ﬂ [51'7" (3 points) C) The built—in potential, ¢i~
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4;. : wag/Z13”) : 2%V/»/%%J
' ' ' :. mew ’ (3 points) D) The maximum electric ﬁeld. a, -245- 2mm 529” . W
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i, . (2 points) E) Select the number of the region with the highest electron concentration: IE: I. The quasi—neutral region on the P-side. . :9”
II. The space charge region on the P-side. )] ale [Igor-e n [.4 ﬁe @1326?” re 1 / r HQ. The space charge region on the N—side wk» (45’ 7 5%? ﬂg/é/ng—a WWII-v . E.
4149”- Q The quasi<neutral region on the N—side. “:2. 2' wk .— f :-
Expain. “,0 3T1: ; /0 a" ._ [ﬂay 5/»; V 1917.; 4’5 l
m’br’ T l -3 \ ‘ Q
V1,, : M :: /D cm In r7mm Q (2 points) F) Using the numbering in part E, list the number(s) of any region(s) inside the depletion region; 31' 2.2: 2. Carrier concentrations and currents in semiconductors F07A A piece of3 Silicon has a uniform donor concentration of 1018 cm'3 and a uniform acceptor concentration of
2111017 cm'3 An applied electric ﬁeld of +10 kV/cm exists in the piece of Silicon. Please determine values and
units for the following quantities at room temperature with VT— — 0.025 V. Use the mobility approximations from
p. 55 of Jaeger & Blalock. , I33?!) : 92 + W 2 -1 4
(3 points) A) Electron concentration. I9 )7 ”3 g" " NT tigt CH1 V S
,1 .3 ‘ J.3><§0‘7 ,cm-3
31 m m > >2».
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(3 pomts) B) Hole concentration. vb l J» 1 s.
N" [0200” '3 + m cm-3
p; _._._ 3/256"! 6.3XSG',
"’ — 8’): 1036“;2
I: a, _ /.2 20/3!" 3
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(2 points) C) Electron mobility ’VT : M fM— "' l0 0" ’P 2):) I" ’
A2170 ”’79-: m1
_—___________,_____.
M— 7,2 * 1.2111999)?” 3/24” 1/ 5
If/ I- 3X/0’m
(2 points) D) Electron diffusivity mg m?" _ ./ -:2me 60/“
arm/“V” ’ 2"” (3 points) E) Election d1ift current density h: V ..._———-
ﬂ”=;/v ,5 =Ww"Z)/~Wé—§/W 239/1955,- ; Wm. (3 points) F) Electron diffusion current /density t
4/ f 1” “ﬂ 7% 1,. 1/”,jé/w, c¢rrlrr [pi/(€14 74M 240 17 i _ (4 points) G) Indicate the direction of each component of current at x = 0 pm by placing arrowheads on the linesbelow: .f/IrlM/L jpdlﬂ; &
E ,
- (Ir/fl - (Inf! . , J" ' .]p 1
l 3. Diode Logic Gate FO7A (12 points) Please analyze the circuit shown to the right using the constant voltage drop model with V0,, = 0.7 V.
Determine the Q—points for each diode and the voltage in the center of the circuit, VX, + 10.0V Hy/yfk‘fjlz—f.’ A Mr
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W ; W:Q,7F7mﬂ W/ V): ~03" W — 4207””? ' p/V/ I] :L 0 J
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