E c. i f. (c) The built-in potential between the collector and emitter is. 18 ae bicb

Transcription

1 haer 8 nergy and Dagram of T 8 a & b or he gven dong concenraons, one comues f - = -05 ev, 049 ev, and 099 ev n he emer, base and collecor, resecvely Also wh a >> d, he - deleon wdh wll le almos eclusvely n he base Lkewse, he majory of he - deleon wdh wll le n he collecor nergy and Dagram c f harge Densy c The bul-n oenal beween he collecor and emer s 8 kt a 50 V ln 006 ln 0 V 5 q a 0 d W W n n n n S q q d S d V b a n a 0m d V b 00m Therefore, W 878m 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

2 e lecrc eld lecrc eld q q S d ma n S d ma n Vcm Vcm f nergy and Dagram c f harge Densy V haracerscs and urren Gan 8 rom q 84 and q 84, Subsung / no, we oban Solvng for yelds 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

3 83 a + : mer f,n+ f, P: ase V s forward based and V s reverse based : ollecor f,n b P P MTTR AS OLLTOR The P,,P on he dagram refer o he mnory carrer ye n each regon The horzonal doed lnes refer o he equlbrum mnory concenraon e 0, n P0 The remanng doed curves corresond o he ecess mnory carrer concenraons Assumons made here: W & W are shorer han he dffuson lenghs of he holes & elecrons resecvely, resulng n a lnear decay of ecess mnory carrers n he emer and base You should also noce ha he scale for he y- as dffers for each regon c ase curren consss of njecon of holes no he emer and recombnaon wh a very small ar of he collecor curren remember ha ~ The collecor curren consss almos enrely of elecrons emed from he forwardbased juncon whch ravel across he juncon ncdenally, an easy way o remember how a T works s o assocae he names emer and collecor wh he hyscal emsson and collecon of he mnory elecrons n he base 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

4 ' 84 n n0 and ' 0' n he base regon, dn qdn 0 n qd d n mer regon, d qd 0 qd d n 0 = 0 3 cm -3, 0 = 0 cm -3, and + = O = 0 5 cm -3 D = 08 cm s -, D =8 cm s -, and D =9 cm s - a 0 qd n 0 / 0666 A cm, n, / 4, ' 0' qd 0 / 36 0 A/ cm, and 0, 05 m qd O / 87 0 A/ cm Therefore, 4 TOTAL, 666A/ cm 36 0 A/ cm 0666A/ 0 cm and TOTAL, n or shor dode aromaon, we assume n - = n =0 More accurae relaonsh s n X - = T n =0 However, snce T, we can sll say n X - = n =0 Hence, TOTAL, 0666 A/ cm n, TOTAL, ' ' 0666 A/ 0 cm n, TOTAL, ' 0666 A/ 4,, 36 0 A/ cm cm 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

5 n W L m b L 0m T n n T a To mrove he emer njecon effcency, and o reduce he back njeced carrers from - b Small means W L, ycally m c W would become a larger ercenage of W Therefore, would ncrease he sloe of ouu characerscs d A very small values of, he recombnaon curren ecessve base juncon curren n he - deleon regon becomes a less sgnfcan ar of as ncreases e A larger values of, due o he hgh level njecon n base, does no ncrease eonenally as does n he moderae level njecon regon 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

6 0 - hgh level njecon n base, A 0-4 A cessve base juncon curren V f Regon V V Acve + - Sauraon + + uoff - - Schoky mer and ollecor 86 a As you wll fnd ou n he laer ar of hs roblem he njecon of majory carrer of he semconducor no he meal s much hgher han he njecon of mnory carrer no he semconducor regon from he meal Ths would make he emer effcency n he T very small! Hence, would no be desrable o use a meal as an emer n a T b We know ha he hole dffuson curren s gven by qva / kt DP n / qva kt dff dff 0 e qa e LP d rom Secon 47 and 48, qva / kt q / kt qva / kt e AKe e e e0 ong ha we have / D L P P D kt q P, 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

7 dff e dff 0 e0 q kt / q Ke / kt n d / e / c A Schoky base-collecor juncon he collecor beng he meal would be funconal n a T The energy dagram of he base-collecor juncon would be smlar o g 4-34b would be effecve collecng he elecrons arrvng a hs juncon from he P ye base o he meal The feld a he Schoky juncon swees he elecrons no he meal collecor jus as n he P base-collecor juncon shown n g 8-b Gummel umber and Gummel Plo 87 a = / =00 b nerce of s 0-0 A/cm = qn Dn / W qn Dn cm 0 0 W c Peak concenraon qv n kt 7 e 0 qv kt 3 e 80 3 V ln8 0 6mV 83mV d n W D n sec bers-moll Model 88 a onsder ha n = n P0 e qva/kt - and = 0 e qva/kt - e, ake a look a he juncon, n / = / Smlarly, a he juncon, /n = / Mully and o ge / = 8/40/ = 0 Thus, = 0 = 0 7 cm Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

8 b The T s oerang n sauraon because boh and juncons are forward-based and he resulng mnory carrer concenraons are larger han he equlbrum values c The sored mnory charge s equal o he area under he curve n he base Aq 0 ' m ' mw coul d n n' m n' 0m ' m ' m Aq[ Dn D ] W W ma 0 9 ma DW 00 5 e 5 7 o much gan 4 D W f he P T s based a he boundary beween acve mode and sauraon mode, hen forward-based emer-base juncon V >0 and unbased collecor-base juncon V =0 So R =0 a A he gven oerang on, we can smlfy he bers-moll model as follows: qv / kt e S b Snce 0 qv S e kt V ln q S kt V V V 0 ln q S Drf-ase Transsors kt q ln S 80 a s ndeenden of changes n base arameers s deenden on base arameers You should convnce yourself ha hs s he case by referrng o 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

9 he curren equaons n he reader f a SGe base s used, c ncreases as a resul of he base bandga narrowng ouled wh a graded base ha shorens base ransor me, SGe-base Ts are a smle and aracve alernave o convenonal S-base Ts * Ths soluon gnores he case of ncreased hole barrer beween base and emer f you wsh o nclude hs effec, hen SGe s ncreased by e g/kt over S b n hs case, n SGe vares along he base regon Ths requres ha we do an negraon o fnd c0 SGe qdn c0 SGe = W g, SGe e d 0 kt W qd n, / kt g SGe = W e / kt g, SGe Dvde c0 SGe by c0 S and you ge he followng: g, SGe / kt SGe/ S = = 4 e / kt g, SGe 8 a nd where d = a o oban he frs juncon e 40 e 077m To oban he second juncon, equae a o he background concenraon e 50 7 m Therefore, he base wdh s - = 05 m Please noe ha he deleon wdhs have been gnored n hs case n general, you mus subrac he deleon regon wdhs n he base n boh he juncons from he meallurgcal base wdh b ase Gummel umber: a d e cm 30 cm Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

10 rom q 8, he base Gummel number s he number above dvded by he elecron dffusvy n he base, whch we shall assume o be around 30 cm /s The resul s 40 0 s-cm -4 mer Gummel umber: 0 d e cm 060 cm d 006 rom q 83, he emer Gummel number s he number above dvded by he hole dffusvy n he base, whch we shall assume o be around cm /s The resul s 0 4 s-cm -4 c Snce he dong level s no consan, we use he average dong denses o esmae he dffusves Average base dong densy: 0 G W cm 460 cm Average emer dong densy: 9 G cm Average elecron dffusvy n he base: kt / q cm s 99cm s D' n n Average hole dffusvy n he emer: kt / q cm s 8cm s D' GD' G D' n d Dffuson curren: dff d D dn d ln n q qd D d n d d 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

11 40 8 e /, 09m D drecon Drf curren: drf q q dff q D and D kt Therefore, k 006 V 5 b 360 V / m q 09 m oe: b should be - drecon so ha dffuson curren and drf curren wll balance q kt D c v f Krk ffec 8 ase - Orgnal ase Wdh + ollecor ollecor ffecve Deleon ase Wdh Layer, W de learly, W _ffecve = W _Orgnal + W -W de W _Orgnal and W are assumed o be known So, n order o fnd W _ffecve, we need o calculae W de 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

12 sa v A q where v sa s he sauraon velocy The lengh of he deleon regon becomes sa s de q v A V W Therefore, sa s Orgnal ffecve q v A V W W W harge onrol Model 83 The equaon descrbng he sysem s d d Snce = 0 for <0 and = 0 for 0, he equaon becomes 0 d d wh he nal condon 0 = 0 Solvng hs equaon yelds e / 0 Hence, e / 0 / 84 e A d d / oundary ondons: A 0, Hence, = - 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

13 Therefore, / e / e, 00, ns hracersc me T And, 0 ma for 0 /ns ma 9 ma e for 0, and 0mA T=s T = ns ma uoff requency 85 onsder he followng fgure: b c Sgnal Source r + v be - gmv be Load b and c are gven by v / nu medance v nu admance v / r b c be g m v be The gan s c b be g m / r j / g r j j d m / j j kt / q be d / g j m 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458

14 f >> so ha / becomes neglgble, he equaon above shows ha /, and becomes a f T d kt / q 00 Pearson ducaon, nc, Uer Saddle Rver, All rghs reserved Ths ublcaon s roeced by oyrgh and wren ermsson should be obaned from recordng, or lkewse or nformaon regardng ermssons, wre o: Rghs and Permssons Dearmen, Pearson ducaon, nc, Uer Saddle Rver, 07458