# Midterm1AF07 - E15 306 F07A MIDTERM EXAM#1 Braun CLOSED...

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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~ ' 7 . /8 "I" 4;. : wag/Z13”) : 2%V/»/%%J ' ' ' :. mew ’ (3 points) D) The maximum electric ﬁeld. a, -245- 2mm 529” . W X" -6 m cm / [Va/g 5, ¥§xm w i S 2 l. E i Q. Q, i l E x V, . 2 ll i i l i 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». . , .~ - 2 -l —l . . 1" ‘ N 11% (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 -3 — J! (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 0% 9V) t W ; W:Q,7F7mﬂ W/ V): ~03" W — 4207””? ' p/V/ I] :L 0 J #ﬂ/ﬂLl/ZEJ {(4 ill/(5 I). z I; + ,, /au— (1470,?» ~ 1/;< _p,;Lv + v, lm ' 5m- 57m Sp/Ve )5? Mt W.5*9-?V-= ;‘ ‘4 V} : 5,5”)‘3 l/ _ _ Vx : «2,753 \/ 50 0 ~ VD, , LH/ i h 5 55/5 ﬂﬂé’fﬁ’f Witt; gar/75 / (WW? 11/7- 5 ya»? P/JFJ?‘ Wrz: IF WW" I}, wax ///p7//£;/5. M 4207 £1/2/ipﬁ 7W” 4’” ”MA/E xy F191? EMW/zé ﬂff‘ﬂm/ﬂ ”4 P I _ cﬂécqéﬂﬂ ; 57;] ‘5' 77/5 1/ WV 64 V55 77”,; ﬂ/Vﬂff 2/6 W” ”iii/7?» [KI/57W ”517 W l i l t 1 l l ...
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