高性能硅基MOS电光相位调制器_英文_

* Proj ect supp ort ed by th e N ation al N at ural Science Foundat ion of Ch ina ( N os. 60536030, 60502005) and t he N at ional High Technol ogy R e sear ch and D evel opment Pr ogram of C hin a ( N o. 2005A A 311030) C orrespondi ng aut hor. E mail: bj huang@ semi. ac. cn R ecei ved 18 A pril 2006, revised manuscr ipt r eceived 22 A ugust 2006 2006 Ch inese In stit ut e of Electr onics
Abstract: W e pr opo se and analy ze a no vel Si base d electro o ptic modulat or w ith an impr o ved me tal ox ide sem i co nducto r ( M OS) ca pa cito r conf ig ur ation integr ated into silicon o n insula tor ( SO I ) . T hr ee g ate o xide laye rs em bedde d in the silico n w ave guide co nstitute a tr iple M O S capacitor structur e, w hich boo sts the modulat io n ef ficiency compar ed with a single M O S capacitor . T he simulation results demo nstr ate that the V L pr oduct is 2 4V cm. The rise time and fa ll time of the pro posed device are calculated t o be 80 and 40ps fr om the tr ansie nt r esponse cur ve, re spectiv ely, indicating a bandwidth o f 8GH z. T he phase shift ef ficiency and ba ndw idth can be enhanced by rib w idth sca ling . Key words: carr ie r accumulation; pla sma disper sion eff ect; electr o o ptic phase mo dula tor ; meta l o xide semicon duct or ; opto ele ctro nic integr ated circuit EEACC: 1250 CLC number: T N36 Document code: A Article ID: 0253 4177( 2006) 12 2089 05
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Introduction
With the dramatic dow n scaling in t he f eat ur e size of int egr at ed cir cuits( IC) , mo re and m ore t ran sist ors can be int egrat ed int o one silico n w afer. T his also improves the per for mance of t he t ran sist ors, but it has a negat ive impact on t he resist ance of met al int erconnect s, w hose delay increases [ 1] w it h t he scaling . Met al int er connects seem t o be the bot t leneck f or t he sy st em perfo rmance o f t he nex t generat ion o f Si int egrat ed cir cuit s. Fo rt unate l y, optical int er connects can ov ercome t he lim ita t ions of convent ional interconnect ion technolog y w it h t heir high speed and low pow er co nsum p [ 2] t ion . Opt oelect ronic int eg rated circuit s ( OEIC ) , w hich int eg rate opt ical elem ent s and advanced elec t ro nics to gether on a sing le silico n substr at e, hav e receiv ed much at t ent ion because of t heir po t ent ial advantages. Several OEIC co mpo nents, such as Si passiv e and activ e element s, including w aveguides [ 3] , co u plers[ 4] , AWGs[ 5] , light em itt ers[ 6] , modula
H uang Beiju , Chen H ongda, L iu Jinbin, Gu Ming, and L iu H aijun
( St at e K ey L abor at ory of I nt egr ate d Op t oe lec tr oni cs , Inst it ut e of Se mic ond uct or s, Chi nese A cade my of S cie nces , Bei j i ng 100083, Chi na)
t ors[ 7~ 14] , and pho to det ecto rs[ 15] , hav e been ex ten sively st udied. Opt ical modulat ors are used to en co de sig nal dat a int o lig ht w aves t o realize opt ical comm unicat io n links in OEIC. F or t heir significant ro le in silico n phot onics, many Si based t hermo op t ic[ 7] and elect ro opt ic[ 8~ 14] modulat ors have been t heo ret ically and exper im ent ally dem onst rated. T he ref ract ive index of a t her mo opt ic m odulat or chan ges w it h t he variat ion of t em perature via t he t her mo o pt ic eff ect . Alt hough t he t her mo opt ic ef fect is remarkable in Si, it is r at her slo w and can pro vide m odulatio n fr equencies o f only 700kH z[ 7] . T he plasma dispersio n ef fect is ex plo it ed t o r ealize higher m odulat io n frequencies t o meet t he require ment of f ast opt ical comm unicat ion syst ems. Dif ferent config urat ions of mo dulato rs based on t he plasm a dispersion ef fect hav e been pro [ 8, 9] posed, including pin diodes , t hree t erminal bipo [ 10] lar m ode field ef f ect t ransist or s( BMF ET ) , met [ 11~ 13] al o xide semico nduct or ( M OS) capacit ors , and + + [ 14] f our term inal p pnn st ruct ur es . F or pin and BMF ET str uct ures, bot h t he ref ract ive index and absorpt ion change t hr oug h carrier inject io n w it h a
第 27 卷 第 12 期 2006 年 12 月
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Vo l. 27 N o. 12 Dec. , 2006
A High Performance Silicon Electro Optic Phase Modulator * with a Triple MOS Capacitor
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posit iv e bias or posit ive current. T hese dev ices ex hibit a low er frequency( several M H z) and a hig her DC po wer compar ed w it h M OS and fo ur t er minal p+ pnn+ st ruct ures, w hose r ef ract ive index es vary w it h car rier accumulat io n o r deplet ion. M OS capac it or modulat ors have dem onst rated experiment ally a m odulatio n frequency of 1GH z[ 11] . Even hig her bandw idt h perf orm ance ( 10GH z ) has been a chieved t hr oug h improv em ent s in mat erial qualit y, device desig n, and driv er circuit ry [ 12] . T he main draw back of the M OS capacit or st ruct ure is t he w eak dependence of silico n s ref ract ive index on e l ectr on hole pair concentr at ion because o f t he small int eract ion reg ion bet w een t he car rier accumulat io n and optical w aveguide mo de [ 8] , w it h t he result t hat the V L is 8V cm. A shunt capacit or config ura t ion has been proposed t o enhance t he light co n f inem ent eff ect in the w av eg uide and enlarge t he ar ea of index chang e r eg io n, resulting in a V of 4V and an act ive region lengt h o f 8mm [ 13] . In t his paper, w e present and simulate a silico n modulat or based o n a tr iple MOS capacito r t o fur t her im pro ve t he ov erlap betw een t he carrier accu m ulat ion regio n and opt ical mo de. T hrough caref ul analysis and soft w are simulat io n, t he device show s a hig her mo dulation eff iciency and a short er act iv e region.