DEULFDWLRQ RI 6XVSHQGHG S*D1 0LFURVWUXF WXUHV

7KH SURFHVV GLVFXVVHG LQ WKLV VHFWLRQ H[SORLWV WKH GRSDQW VHOHFWLYLW\ RI SKRWRHOHFWURFKHPLFDO 3(& HWFKLQJ WR XQGHUFXW S*D1 OD\HUV JURZQ RQ VDFULnFLDO Q*D1 OD\HUV 7R IDEUL FDWH FRPSOH[ PLFURVWUXFWXUHV LQ S*D1 KRZHYHU WKLV XQGHUFXWWLQJ PXVW EH SUHFLVHO\

FRQWUROOHG DQG RSWLPL]HG )RU RQH HWFKLQJ PXVW EH SUHYHQWHG LQ UHJLRQV RI WKH QW\SH XQGHUOD\HU GHVLJQHG WR SURYLGH PHFKDQLFDO DQFKRULQJ IRU WKH SW\SH PHPEUDQH DERYH )XUWKHUPRUH IRU VWUXFWXUHV ZLWK D ODUJH XQGHUFXW VSDQ WKH ODWHUDO HWFK UDWH PXVW EH KLJK WR DFKLHYH D SUDFWLFDO WRWDO HWFK WLPH

)LJ D VKRZV WKH VDOLHQW IHDWXUHV RI WKH HWFK VHWXS XVHG IRU FRQWUROOHG XQ GHUFXWWLQJ RI S*D1 ,Q WKHVH H[SHULPHQWV SRQQ ELOD\HU VDPSOHV ZHUH LPPHUVHG LQ HLWKHU 0 .2+ RU +32 S+ DQG H[SRVHG IURP WKH IURQW VLGH E\ D ;HQRQ DUF ODPS ZLWK P: FP LQ WKH 89 QP 3ULRU WR WKH 3(& HWFK RSDTXH PHWDO PDVNV ZHUH SDWWHUQHG RQWR VHOHFWHG UHJLRQV RI WKH VDPSOH VXUIDFH 7\SLFDOO\ WKHVH PDVNV ZHUH WKHQ DQQHDOHG z ^p& IRU PLQXWHV LQ $U WR SURPRWH DGKHVLRQ DQG WKHUHE\ SUHYHQW VXEVHTXHQW SHHOLQJ LQ WKH FRUURVLYH FKHPLFDO EDWK

$V GHSLFWHG LQ WKH )LJ WKH QW\SH VDFULnFLDO OD\HU GRHV QRW HWFK LQ WKH DUHDV LPPHGLDWHO\ EHORZ WKH PDVNV DOORZLQJ WKHVH UHJLRQV WR IRUP PHFKDQLFDO DQFKRUV IRU WKH OD\HU VXVSHQGHG DERYH +RZHYHU PDVNHG UHJLRQV QHDU WKH RXWHUPRVW SHULSKHU\

RI WKH RYHUOD\HU ZHUH VHHQ WR XQGHUFXW VORZO\ DV D UHVXOW RI VWUD\ 89 UDGLDWLRQ WKDW LV UHoHFWHG EDFN WKURXJK WKH VDSSKLUH VXEVWUDWH GLUHFWO\ LQWR WKH Q*D1 OD\HU 7R VXSSUHVV WKLV UHoHFWLRQ VDPSOHV ZHUH QRW HWFKHG RQ D KROGHU LQ VROXWLRQ EXW ZHUH LQVWHDG VXVSHQGHG LQ VROXWLRQ E\ D 1L ZLUH HSR[LHG RQ WKH *D1 VXUIDFH QHDU DQ HGJH 7KLV VWUD\ UDGLDWLRQ FRXOG EH HmHFWLYHO\ HOLPLQDWHG E\ XVLQJ D EDFNVLGH SROLVKHG VXEVWUDWH ZLWK D WKLQ DQWLUHoHFWLRQ FRDWLQJ

7KH 1L ZLUH DOVR VHUYHG DV WKH HOHFWULFDO FRQWDFW WR WKH *D1 HOHFWURGH RI WKH HOHFWURFKHPLFDO FHOO ,W ZDV PDLQWDLQHG DW D SRVLWLYH 9 ELDV ZLWK UHVSHFW WR D 3W FDWKRGH LQ VROXWLRQ 7KH DSSOLFDWLRQ RI WKLV ELDV ZDV VHHQ WR GUDPDWLFDOO\ DFFHOHUDWH WKH XQGHUFXWWLQJ RI WKH XQPDVNHG S*D1 DUHDV ZLWK ODWHUDO HWFK UDWHV LQ H[FHVV RI

p-GaN MEMS Fabrication using PEC Etching

Pt Cathode

Aqueous KOH (pH ~14) UV (Xenon Arc Lamp)

n-GaN

E_C

E_V E_F

GaN Electrolyte

n-GaN

p-GaN

Sapphire p-GaN Opaque Mask Sample Bias

(~ +0.5 V)

Holes drawn to surface

Holes repelled from surface

(a)

(b)

)LJXUH D 6FKHPDWLF RI WKH 3(& HWFK VHWXS XVHG WR XQGHUFXW S*D1 OD\HUV E 6FKHPDWLF EDQG GLDJUDP IRU ERWK GRSLQJ W\SHV ZKHQ LPPHUVHG LQ WKH HOHFWURO\WH 1RWH WKDW EDQG EHQGLQJ DWWUDFWV SKRWRJHQHUDWHG KROHV WR WKH VXUIDFH LQ Q*D1 EXW UHSHOV WKHP LQ S*D1

xPPLQ EHLQJ REVHUYHG IRU FHUWDLQ JHRPHWULHV 7KH RULJLQV RI WKLV PDUNHG LQFUHDVH LQ HWFK UDWH DUH QRW IXOO\ XQGHUVWRRG DW WKLV WLPH +RZHYHU REVHUYDWLRQV RI WKH XQGHUFXWWLQJ G\QDPLFV VXJJHVW WKDW WKH VDPSOH ELDV JLYHV ULVH WR GULIW FXUUHQWV RI WKH HOHFWURO\WH ZLWKLQ WKH QDUURZ HWFKHG FKDQQHOV XQGHU WKH S*D1 nOP 7KHVH FXUUHQWV ZRXOG GHOLYHU FKHPLFDOO\ DFWLYH 2+^b UDGLFDOV WR WKH HWFK IURQW PXFK PRUH HpFLHQWO\

WKDQ GLmXVLRQ DORQH

(YHQ ZLWK GULIW FXUUHQWV LQ WKH HOHFWURO\WH WKH KLJK ODWHUDO HWFK UDWHV DFKLHYHG DUH VXUSULVLQJ JLYHQ WKH ODUJH RSWLFDO WKLFNQHVV RI WKH S*D1 OD\HUV LQ RXU H[SHULPHQWV 8VLQJ YDOXHV IRU WKH RSWLFDO DWWHQXDWLRQ FRQVWDQW my >@ RI XQGRSHG *D1 DQG WKH LQWHQVLW\ VSHFWUXP RI WKH ;HQRQ DUF ODPS ZH FDOFXODWH WKDW RQO\ RI WKH WRWDO RSWLFDO DEVRUSWLRQ ZLOO RFFXU LQ WKH Q*D1 EHORZ D xP SOD\HU 7KH UHVXOWLQJ KROH JHQHUDWLRQ UDWH LQ WKH QOD\HU LV PRVW OLNHO\ QRW HQRXJK WR VXVWDLQ WKH HWFK UDWHV REVHUYHG ,QVWHDG ZH EHOLHYH WKDW KROHV DUH LQMHFWHG IURP WKH SOD\HU DERYH DV WKH UHVXOW RI D OLJKWLQGXFHG IRUZDUG ELDVLQJ RI WKH SQ MXQFWLRQ /LNH KROHV WKDW DUH GL UHFWO\ SKRWRJHQHUDWHG LQ WKH QOD\HU WKHVH LQMHFWHG KROHV DUH VXEMHFW WR UHFRPELQDWLRQ WKHUH URXJKO\ VSHDNLQJ WKRVH ZLWKLQ D GLmXVLRQ OHQJWK/_S RI WKH HOHFWURO\WH LQWHUIDFH ZLOO UHDFK WKH VXUIDFH WR SDUWLFLSDWH LQ 3(& HWFKLQJ

:KHQ D ELOD\HU VDPSOH LV H[SRVHG WR 89 UDGLDWLRQ IURP WKH IURQWVLGH HK SDLUV DUH FUHDWHG SUHGRPLQDQWO\ LQ WKH WRS SOD\HU 0LQRULW\ FDUULHU HOHFWURQV ZKLFK UHDFK WKH HGJH RI WKH GHSOHWLRQ UHJLRQ DUH VZHSW DZD\ E\ WKH EXLOWLQ nHOGV DW WKH MXQFWLRQ JLYLQJ ULVH WR D SKRWRHOHFWURQ FXUUHQW -SH IURP WKH SOD\HU LQWR WKH QOD\HU ,Q WKH VWHDG\VWDWH WKH SRWHQWLDO GURS DFURVV WKH MXQFWLRQ LV UHGXFHG WR FRPSHQVDWH IRU WKLV FXUUHQW ,Q WKLV IRUZDUG ELDVHG FRQnJXUDWLRQ D KROH GLmXVLRQ FXUUHQW -GK oRZV RYHU WKH SRWHQWLDO EDUULHU IURP WKH SOD\HU LQWR WKH QOD\HU ZKLOH DQ HOHFWURQ GLmXVLRQ FXUUHQW-GH oRZV LQ WKH RSSRVLWH VHQVH :LWKRXW DQ\ oRZ RI FKDUJH EHWZHHQ WKH HOHF WURO\WH DQG WKH VDPSOH >@ WKHVH FXUUHQWV PXVW FDQFHO WKH SKRWRJHQHUDWHG HOHFWURQ FXUUHQW -SH -GK -GH ,JQRULQJ VXUIDFH UHFRPELQDWLRQ RQ WKH IURQWVLGH RI WKH SOD\HU >@ DV ZHOO DV UHFRPELQDWLRQ LQ WKH GHSOHWLRQ UHJLRQ WKH KROH FXUUHQW LQMHFWHG LQWR WKH QW\SH OD\HU IROORZV IURP WKH VWDQGDUG WKHRU\ RI D SQ MXQFWLRQ VRODU

FHOO >@

-GK )^r m/Q

m/Qb

sr xSPS

x_SPSx_QPQ

KH^c[^S^/^QbH^bmc[^SbWDQK^r^c[_/_Q^S^sr^H^bmc[S_m/_Q H^c[^S^/^Q^sL

ZKHUH S DQG Q DUH WKH PDMRULW\ FDUULHU FRQFHQWUDWLRQV LQ HDFK OD\HU xSP DQG xQP

DUH WKH PLQRULW\ FDUULHU PRELOLWLHV/_QLV WKH HOHFWURQ PLQRULW\ FDUULHU GLmXVLRQ OHQJWK c[S LV WKH SOD\HU WKLFNQHVV DQG) LV WKH LQFLGHQW SKRWRQ oX[ ,Q WKH UHJLPH m /Q [S -GK GHFD\V ZLWK WKH SOD\HU WKLFNQHVV OLNH H[S bc[S /Q ZKLOH WKH OLJKW LQWHQVLW\ GHFD\V PXFK PRUH VKDUSO\ OLNH H[S bmc[S )RU WKLV UHDVRQ GLmXVLRQ EHFRPHV WKH SULPDU\ VRXUFH RI KROHV LQ WKH QOD\HU 7KLV DUJXPHQW LV VWUHQJWKHQHG E\ UHFHQW UHSRUWV RI ODUJH YDOXHV IRU /Q DIWHU H[WHQGHG SHULRGV RI PLQRULW\ FDUULHU LQMHFWLRQ LQ S*D1 >@ 8VLQJ /Q xP >@ xSP xQP FP 9 V >@

DQG LQWHJUDWLQJ RYHU WKH VSHFWUXP RI WKH OLJKW VRXUFH LW LV FDOFXODWHG WKDW WKH KROH GLmXVLRQ FXUUHQW GHQVLW\ GRPLQDWHV WKH KROH SKRWRJHQHUDWLRQ UDWH SHU XQLW DUHD LQ WKH QOD\HU E\ D IDFWRU RI IRU D xP SW\SH RYHUOD\HU

)LJ VKRZV DQ DVVRUWPHQW RI FRQYHQWLRQDO 0(06 GHYLFH JHRPHWULHV WKDW ZHUH IDEULFDWHG LQ S*D1 ZLWK WKH 3(& SURFHVV GHVFULEHG DERYH 7KH LQWHQW RI WKHVH GHYLFHV ZDV PDLQO\ WR H[SORUH DQG UHnQH WKH HWFK SURFHVV ,Q DOO WKUHH FDVHV WKH IROORZLQJ JHQHUDO UHFLSH ZDV XVHG

'HSRVLW PHWDO ,Q WKLV VWHS PHWDO LV VSXWWHU GHSRVLWHG RQ VHOHFWHG DU HDV RI WKH *D1 VXUIDFH 7KHVH PHWDO DUHDV ZLOO ODWHU VHUYH DV RSDTXH PDVNV IRU WKH 3(& SURFHVV WKHUHIRUH WKH\ GHOLQHDWH WKH UHJLRQV RI WKH GHYLFH ZKLFK ZLOO UHPDLQ DQFKRUHG WR WKH VDSSKLUH VXEVWUDWH 7KH FKRLFH RI PHWDO PXVW EH FRPSDWLEOH ZLWK WKH 3(& FKHPLVWU\ 1L $X 3W DQG 7L DUH DOO UREXVW LQ .2+

$V PHQWLRQHG HDUOLHU WKH PDVNV DUH W\SLFDOO\ DQQHDOHG DW ORZ WHPSHUDWXUH WR SURPRWH DGKHVLRQ WR WKH *D1 VXUIDFH

&$,%( HWFK ,Q WKH nUVW SDUW RI WKLV SURFHVV FRQYHQWLRQDO OLWKRJUDSK\ LV XVHG WR SDWWHUQ D OD\HU RI SKRWRUHVLVW WR FRYHU RQO\ WKRVH UHJLRQV RI WKH SOD\HU

Voltage Tunable

Dalam dokumen Development of micro-electromechanical systems in GaN (Halaman 107-111)