Chatr 6. -jucto dod: -V charactrstcs Tocs: stady stat rsos of th jucto dod udr ald d.c. voltag. ucto udr bas qualtatv dscusso dal dod quato Dvatos from th dal dod Charg-cotrol aroach Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-1
Carrr flow qulbrum Elctro dffuso currt s rcsly balacd by lctro drft currt. drft dffuto hol dffuso currt s also balacd by hol drft currt. drft dffuto Thus, o t currt across th jucto. Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-
Carrr flow udr forward bas drft drft dffuto dffuto from - to - sd s th ottal hll larly dcrass wth th forward bas, th umbr of majorty carrrs whch hav suffct rgy to surmout th ottal barrr otally gos u wth V. t s ctd that forward currt.., majorty carrr dffuso currt otally crass wth V. Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-3
Carrr flow udr rvrs bas Th majorty carrr dffuso across th jucto s glgbl. Th morty carrr drft s stll allowd to flow th rvrs currt.., morty carrr drft currt across th jucto from - to -sd. Th rvrs currt s ctd to b trmly small magtud, du to th low coctrato of th morty carrrs. s V gatvly crass, th rvrs currt s also ctd to saturat, oc th majorty carrr dffuso currts ar rduc to a glgbl lvl at a small bas. Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-4
Ch 6-1 Th dal dod quato Nt currt = dff drft t qulbrum V =, t currt = st dff V drft V drft saturats ad dos ot chag wth V Why? Bcaus th drft currt s lmtd NOT by HOW FST carrrs ar swt across th dlto layr, but rathr HOW OFTEN. thk a watrfall! dff vars otally wth V Why? Bcaus th umbr of carrrs whch hav suffct rgy to surmout th ottal barrr otally gos u wth V. Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-5
Ch 6-1 Th dal dod quato dff = V /V rf whr ad V rf ar costats. t ay ald voltag, V, sc drft = at ay voltag. V V V V V rf rf V rf drft 1 V V rf 1 Prdctd quato for dal dods Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-6
jucto udr varous bas codtos V = V > V < E E E Majorty hol dffuso currt Morty hol drft currt Majorty lctro dffuso currt Morty lctro drft currt Majorty hol dffuso currt Morty hol drft currt Majorty lctro dffuso currt Morty lctro drft currt Majorty hol dffuso currt Morty hol drft currt Majorty lctro dffuso currt Morty lctro drft currt Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-7
dal dod quato: quattatv soluto ssumtos whch must hold Th dod s bg oratd udr stady stat codtos o-dgratly dod st jucto modls th dog rofl Th dod s o-dmsoal Low-lvl jcto rvals th quas-utral rgos Thr ar o rocsss othr tha drft, dffuso, ad thrmal rcombato-grato takg lac sd th dod, scfcally, G L = Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-8
dal dod quato: quattatv soluto W wat to obta a currt quato of dod agast V. Thrfor th total currt ca b obtad from th total currt dsty. qμ E Not that th total currt dsty s costat throughout th dod udr th stady stat, but th ad vary wth osto. qd d d Th ad should b rssd as a fucto of by usg th followg quatos, qμ E qd Th ad ca b valuatd by usg th cotuty quato. d d Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-9
Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-1 dal dod quato: quattatv soluto Quas-utral rgo cosdrato for lctros -ty L G D t for hols -ty L G D t Lt s cosdr th ad th quas-utral rgos, bcaus th cotuty quato ca b smlfd to th morty carrr dffuso quato ths rgo ot that E ad th low lvl jcto assumto. dffusoquato Morty carrr
dal dod quato: quattatv soluto Quas-utral rgo cosdrato Udr th assumto of th stady stat wth G L =, lrady w kow th gralsoluto / L D Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-11 D - Sc E ad d /d = d /d = th quas-utral rgo, ot that = + Δ ad = + Δ qμ qμ E E B qd qd / L d d d d qd qd / L B d d d d L / -
dal dod quato: quattatv soluto Dlto rgo cosdrato th dlto rgo, E so, th cotuty quato must b usd udr our assumtos stady stat ad oly thrmal R-G rocss. t 1 q t thrmal RG t othrs lght tc. 1 q t thrmal RG t 1 q t thrmal RG t othrs lght tc. 1 q t thrmal RG ddtoally, w ca assum that thrmal R-G rocss s glgbl throughout th dlto rgo. Thus, ad at Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-1
Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-13 dal dod quato: quattatv soluto Dlto rgo cosdrato ad at Ths rvals th costacy of th carrr currts throughout th dlto rgo cludg th dgs. Summg two quatos,
dal dod quato: quattatv soluto Boudary codtos f th ohmc cotacts ar far ough from th dgs of th dlto rgo, th boudary codtos at th ohmc cotacts wll b [Bad dagram sd a forward-basd dod] Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-14
Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-15 dal dod quato: quattatv soluto Boudary codtos N E F l P E F l To stablsh th boudary codtos at th dgs of th dlto rgo, cosdr th dfto of th quas-frm lvls. E F F E Thus, F F
dal dod quato: quattatv soluto Boudary codtos F F E F E F qv [F ad F varato sd a forward-basd dod] ssumg F, ad throughout F qv F E F F EF th dlto rgo, F F E E qv F F Thrfor, Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-16 qv / Ths quato s rfrrd to as th law of th jucto.
Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-17 qv / dal dod quato: quattatv soluto Boudary codtos t th -dg of th dlto rgo, qv N / qv N / qv N N / 1 / qv N Smlarly at th -dg, or Th, 1 / qv D N
D Pla for th quattatv soluto 1 Solv th morty carrr dffuso quatos mloyg boudary codtos - D / L / L B B / L / L qv / 1 qv / 1 N N D Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-18
Pla for th quattatv soluto Comut th morty carrr currt dsts th quasutral rgos usg qd qd d d d d - 3 Evaluat th quas-utral rgo solutos for ad at th dgs of th dlto rgo ad th sum th two dg currt dsts. 4 Fally, multly th rsult by th cross-sctoal ara of th dod. Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-19
oucmts Nt lctur:. 47 ~ 59 Prof. Yo-S M Elctroc Matrals: Smcoductor Physcs & Dvcs Chat. 5 - Lc 11-