5NIFORM !G 4HIN &ILM 'ROWTH ON AN 3B TERMINATED 3I 3URFACE

%42) *OURNAL VOLUME  NUMBER  *ULY  

5NIFORM !G 4HIN &ILM 'ROWTH ON AN 3B TERMINATED 3I 3URFACE

+ANG (O 0ARK *EONG 3OOK (A AND %L (ANG ,EE

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))) !G '2/74( /. #,%!. 3I

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6 35--!29

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!"342!#4

7E REPORT ON THE ROOM TEMPERATURE GROWTH OF HIGHLY UNIFORM AND ULTRATHIN !G

`LMS ON 3B TERMINATED 3I SURFACES AS EVIDENCED FROM A SCANNING TUNNELING MI CROSCOPY 34- STUDY IN AN 5(6 SYSTEM

7ITH PREDEPOSITION OF ONE MONOLAYER -, OF 3B UNIFORM GROWTH OF !G ISLANDS WAS OB SERVED AT ROOM TEMPERATURE 4HE 3B LAYER SUPPRESSES THE SURFACE DI_USION OF !G ATOMS ON 3I SURFACE AND INCREASES THE !G ISLAND DEN SITY AND THEN THE INCREASED ISLAND DENSITY IS BELIEVED TO CAUSE COALESCENCE OF !G ISLANDS BEFORE THE BEGINNING OF MULTILAYER GROWTH IN HIGHER COVERAGES RESULTING IN THE GROWTH OF ATOMICALLY aAT AND UNIFORM ISLANDS ON THE 3B SURFACTANT LAYER

 +ANG (O 0ARK ET AL %42) *OURNAL VOLUME  NUMBER  *ULY 

) ).42/$5#4)/.

4HE GROWTH OF METALS ON SEMICONDUC TORS HAS BEEN A LONG STANDING ISSUE IN CUR RENT RESEARCH ON SEMICONDUCTOR DEVICES

4HE OHMIC AND 3CHOTTKY BARRIER CONTACTS ON SILICON HAVE BEEN IMPORTANT APPLICATIONS OF THIS BRANCH OF SEMICONDUCTOR TECHNOL OGY !G GROWTH ON 3I HAS BEEN AN ES PECIALLY INTERESTING SUBJECT IN THE AREA OF METAL GROWTH ON SEMICONDUCTORS DUE TO ITS ABRUPT INTERFACE AND ELECTRONIC POTENTIAL

;= ;= (OWEVER IT HAS BEEN IMPOSSIBLE TO ACHIEVE EPITAXIAL LAYER BY LAYER GROWTH OF !G ON 3I AT ROOM TEMPERATURE

!G `LMS GROWN ON 3I AT ROOM TEM PERATURE HAVE BEEN SHOWN TO FOLLOW THE 3TRANSKI +RASTANOV MODE OF GROWTH LAYER PLUS ISLAND GROWTH ;= ;= 5P TO THE LEVEL OF A MONOLAYER !G ATOMS LOCATE THEMSELVES ON SUBUNITS OF THE r CELL DUE TO THE STRONG INTERACTION BETWEEN !G ATOMS AND THE 3I DANGLING BONDS ON THE r UNIT CELL !BOVE A MONOLAYER COVERAGE  DIMENSIONAL $

!G ISLANDS CAN BE FOUND ON THE INTERME DIATE !G LAYER ;= )T IS ONLY AT LOW TEM PERATURES THAT THE GROWTH MODE OF !G ON 3I RESTRICTS ITSELF TO $ GROWTH ;=

3INCE ULTRATHIN METALLIC `LMS WITH ATOMICALLY aAT SURFACES ARE IMPORTANT MODEL SYSTEMS IN THE STUDY OF $ PHENOM ENA THE OBSERVATION OF THE $ LAYER LIKE GROWTH OF !G ON 3I AT LOW TEMPERA TURE WAS A REMARKABLE DISCOVERY 2ECENTLY THE EPITAXIAL GROWTH OF HETERO INTERFACE SYSTEMS SUCH AS 'E3I HAS BEEN DEMON STRATED ;= ;= 4HE SMOOTH LAYER BY LAYER GROWTH OF 'E ON 3I HAS BEEN

ACHIEVED THROUGH THE USE OF !S AND 3B AS SURFACTANTS AND THE ROLE OF SURFACTANTS IN HETEROEPITAXY HAS EMERGED AS AN ISSUE OF FUNDAMENTAL INTEREST 4HE ROLE OF SURFAC TANTS IN LAYER BY LAYER GROWTH HAS ALSO BEEN STUDIED IN CONNECTION WITH THE HOMOEPI TAXY OF !G ;= ;= SINCE IN THE ABSENCE OF A SURFACTANT MULTI LAYER GROWTH PREVAILS AT ROOM TEMPERATURE

4HE IDEAL SURFACTANT MUST SEGREGATE ON THE SURFACE DURING GROWTH LEAVING THE SUB STRATE AND GROWING `LM UNPERTURBED AND RESTRICTING ISLANDING ! GREAT DEAL OF RE SEARCH INTO HOW THIS HAPPENS HAS BEEN DONE

;= ;= !LTHOUGH THE KINETIC E_ECT OF SUR FACTANTS IN METAL ON METAL GROWTH SYSTEMS IS STILL CONTROVERSIAL ;= ;= THREE MOD ELS HAVE BEEN SUGGESTED 4HE `RST IS THAT SURFACTANT SUPPRESSES SURFACE DI_USION OF METAL ATOMS ON THE METAL SUBSTRATE ;=

WHICH INCREASES ISLAND DENSITY ;= $UE TO THE INCREASED ISLAND DENSITY ISLANDS CO ALESCE INTO LARGER ONES BEFORE MULTILAYER GROWTH OCCURS 4HE SECOND MODEL SUG GESTS THAT SURFACTANT LOWERS INTERLAYER DIF FUSION BARRIERS WHICH CAN A_ECT E_ECTIVELY THE DOWNWARD MASS TRANSPORT SINCE THE UP WARD INTERLAYER DI_USION BARRIER IS LARGER THAN THE DOWNWARD ONE ;= SO ADATOMS ON ISLANDS CAN EASILY HOP DOWN THE DE SCENDING STEPS OF THE ISLAND )N THIS CASE THE  DIMENSIONAL $ ISLAND SIZE IS EN LARGED WHICH IS FAVORABLE FOR LAYER BY LAYER GROWTH 4HE THIRD SUGGESTION IS THAT 3B LOWERS THE MOBILITY ALONG STEP EDGES INDUC ING DENDRITIC ISLAND SHAPES WHICH FURTHER ENHANCES INTERLAYER TRANSPORT ;=

%42) *OURNAL VOLUME  NUMBER  *ULY  +ANG (O 0ARK ET AL 

(OWEVER FEW APPLICATION OF SURFACTANT TO THE LAYER BY LAYER GROWTH OF METALS ON SEMICONDUCTORS HAVE BEEN REPORTED ;=

;= )N ONE STUDY CHANGES IN THE GROWTH MODE CAUSED BY THE USE OF THE SURFACTANT 3B IN !G GROWTH ON 3I AT ELEVATED TEMPERATURE  + WERE MEASURED USING LOW ENERGY ELECTRON MICROSCOPY ,%%-

;= 6ERY DENSE NUCLEATION OF !G ISLANDS ON THE 3B TERMINATED 3I SURFACE AT EL EVATED TEMPERATURE  + WAS OBSERVED WHILE THE LARGE AND WIDELY SPACED $ !G ISLANDS ;= WERE OBSERVED IN THE GROWTH OF !G ON CLEAN 3I AT THIS TEMPERA TURE !LTHOUGH 3B DOES NOT COMPLETELY SUPPRESS $ ISLAND FORMATION ALMOST COM PLETELY CLOSE PACKED !G `LM WAS GROWN US ING 3B AS A SURFACTANT

)N ORDER TO GROW A UNIFORM AND SMOOTH

!G `LM ON 3I AT ROOM TEMPERATURE WE CHOSE 3B AS A SURFACTANT IN THIS STUDY !T

`RST WE OBTAINED THE STRUCTURES OF 3B OVER LAYER ON 3I  !G `LMS WERE GROWN UPON THIS 3B TERMINATED SURFACE 3MALL SIZED !G ISLANDS WERE FORMED AT THE INITIAL STAGE OF

!G GROWTH WITHOUT THE WETTING LAYER OF

!G !S THE !G COVERAGE INCREASED aAT

!G ISLANDS FORMED UNIFORMLY ACROSS THE 3B TERMINATED SURFACE AND COALESCED INTO LARGE DENDRITIC ISLANDS 4HE KINETIC ORIGIN OF THE aAT AND UNIFORM GROWTH OF !G `LM ON 3B TERMINATED 3I IS BELIEVED TO BE THE SUPPRESSION OF THE DI_USION OF !G ATOMS OWING TO THE 3B SURFACTANT WHICH WILL BE DISCUSSED IN SESSION )6 %VEN THOUGH 3B DOES NOT COMPLETELY SUPPRESS ISLANDING EF FECTS IN THE INITIAL STAGE OF !G GROWTH IN THE

!G3B3I SYSTEM THIS WORK CLEARLY SHOWED THAT THE USE OF AN 3B SURFACTANT EN COURAGES UNIFORM GROWTH OF !G `LMS ON AN 3I SUBSTRATE 4HIS OBSERVATION IS TECHNOLOG ICALLY VERY IMPORTANT SINCE IT MEANS THAT ATOMICALLY SMOOTH AND UNIFORM ULTRATHIN METAL `LMS CAN BE GROWN ON SEMICONDUC TORS AT ROOM TEMPERATURE

)) %80%2)-%.4

7E OBTAINED A CLEAN AND DEFECT FREE 3I r SURFACE BY REPEATED CYCLES OF aASHING ! 3I SAMPLE WAS KEPT IN A VAC UUM AT  ^b# FOR SEVERAL HOURS IN ORDER TO REMOVE THE THICK SILICON OXIDE LAYER AND IT WAS THEN HEATED UP TO  ^b# BY RE SISTIVE HEATING FOLLOWED BY SUBSEQUENT AN NEALING !S SHOWN IN &IG  THE r STRUC TURE OF 3I WAS CLEARLY OBSERVED 3INCE THE FAULTED HALVES OF r UNIT CELLS HAVE LARGER CHARGE DENSITIES IN THEIR `LLED STATES ADATOMS IN THE FAULTED HALVES ARE SEEN TO PROTRUDE MORE THAN THOSE IN THE UNFAULTED HALVES !N OPTICAL PYROMETER WAS USED TO MEASURE THE TEMPERATURE OF THE 3I SUB STRATE 3B WAS EVAPORATED FROM A WATER COOLED +NUDSEN CELL )N ORDER TO OBTAIN AN 3B MONOLAYER ON 3I   -, OF IT WAS DEPOSITED ON A 3I r SUBSTRATE AT A SUBSTRATE TEMPERATURE OF  ^b# 4HIS IS BELOW THE DESORPTION TEMPERATURE FOR THE

`RST MONOLAYER OF 3B BUT ABOVE THE DES ORPTION TEMPERATURE FOR THE SE COND LAYER OF 3B 4HE 3B OVERLAYER STRUCTURES WERE MONITORED WITH 5(6 ,%%$ AND 34-

 +ANG (O 0ARK ET AL %42) *OURNAL VOLUME  NUMBER  *ULY 

&IG  r STRUCTURE OF CLEAN 3I SURFACE 3CAN AREA !r^b ! 6^b 3p 6 )_T N!

!G WAS EVAPORATED FROM A HOT TUNG STEN `LAMENT UNDER EPITAXIAL GROWTH CONDI TIONS i -,MIN  4HE THICKNESSES OF 3B AND !G `LMS WERE MEASURED USING THE QUARTZ CRYSTAL OSCILLATOR ! MONOLAYER

-, OF !G WAS DE`NED AS ONE ATOM PER

r SURFACE UNIT CELL OF THE BULK !G

SUBSTRATE LATTICE r^ ATOMS PER CM^  AND FOR THE GROWTH ON THE CLEAN 3I THE DE`NITION OF MONOLAYER ON 3I WAS ALSO CONSIDERED r^ ATOMS PER CM^ 

))) !G '2/74( /. #,%!.

3I

/N THE CLEAN 3I r SURFACE WE DE POSITED !G EPITAXIALLY AT ROOM TEMPERA TURE !T THE SUBMONOLAYER LEVEL OF COVER AGES WE OBSERVED SMALL ISLANDS WHICH PRE SERVED THE r UNIT CELL PATTERN AS SHOWN

&IG  0ARTLY PACKED TRIANGULAR ISLANDS AND THEIR

COALESC ENCE IN  -, !G `LMS GROWN ON 3I r SURFACE AT ROOM TEMPERATURE 3CAN AREA !r^b ! 6^b 3p 6 )_T N!

IN &IG  4HIS RESULT IS SIMILAR TO THAT OB TAINED IN !G DEPOSITION AT SUBSTRATE TEM PERATURES OF i ^b# ;= 4HE DANGLING BONDS OF REST ATOMS AND ADATOMS ON THE

r UNIT CELL ARE THE MOST FAVORABLE SITES FOR AN ADSORBED !G ATOM IN THE INITIAL STAGE OF !G DEPOSITION AND AMONG THEM THE DANGLING BONDS IN THE FAULTED HALVES OF r UNITS WERE MORE REACTIVE TO THE !G ATOMS 4HE BONDING PROBABILITY ON THE FAULTED HALVES OF THE WHOLE !G ISLANDS WAS ESTIMATED TO BE  AT  -, WHICH IS ESTIMATED AS  MONOLAYER REFERENCED TO 3I SURFACE !S !G ISLANDS GROW THE SIZE AND SHAPE OF ISLANDS CHANGE FROM CIR CULAR TYPES TO PARTIALLY PACKED TRIANGULAR ONES WHICH IS ATTRIBUTABLE TO THE CHARAC TERISTICS OF THE SUBUNITS OF r STRUCTURE

4HE HEIGHT OF THE !G LAYER ADSORBED ON THE 3I ADATOMS WAS ESTIMATED TO RANGE FROM 

TO !^b

%42) *OURNAL VOLUME  NUMBER  *ULY  +ANG (O 0ARK ET AL 

!BRUPT CHANGES IN GROWTH PATTERN ABOVE THE DANGLING BOND SATURATION COV ERAGE CAN BE CLEARLY OBSERVED IN &IG 

&LAT ISLANDS WITH RELATIVELY LARGE AREAS OF

i !^b



AND WITH VARIOUS HEIGHTS FROM  TO ! APPEAR UPON THE `RST INTER ^b MEDIATE !G LAYER WITH DEPOSITION OF A 

-,  MONOLAYER REFERENCED TO 3I

SURFACE !G `LM &IG A  !T  -,

 MONOLAYER REFERENCED TO 3I SUR FACE OF !G `LM THE HEIGHT OF aAT !G IS LANDS INCREASED RANGING FROM  TO  !^b AND THEN THE !G ISLANDS COALESCED 4HE ISLAND HEIGHTS WERE ESTIMATED FROM THE Z DIRECTIONAL 0:4 BIAS VOLTAGES IN THE CON STANT CURRENT MODE AND THEIR HISTOGRAM

4HESE aAT ISLANDS HAVE AN INTERESTING STRUC TURAL BEHAVIOR WHICH IS VERY DI_ERENT FROM THAT OF THE INTERMEDIATE !G LAYER 4HE HEIGHT OF THE `RST !G LAYER RANGED FROM 

TO  ! BUT THE STEP HEIGHTS OF THE SECOND^b AND SUBSEQUENT !G LAYER RANGED FROM  TO

! 4HESE STEP HEIGHTS OF THE aAT ISLANDS^b ARE COMPARABLE TO THE  ! STEP HEIGHT^b OF AN !G SURFACE 4HIS SUGGESTS THAT THE SURFACE NORMAL FACETS OF !G ISLANDS BE IN THE DIRECTION OF  

4HIS FEATURE OF ISLAND FORMATION DIF FERED STRIKINGLY FROM EPITAXIAL GROWTH 5P TO THE DANGLING BOND SATURATION COVERAGE UNIFORM LAYER GROWTH WAS ESTABLISHED DUE TO THE STRONG INTERACTION BETWEEN ADSORBED

!G ATOMS AND SUBSTRATE 3I ATOMS (OW EVER ABOVE THE DANG LING BOND SATURATION COVERAGE THE INTERACTION BETWEEN ADSORBED

!G ATOMS COMES TO PLAY AN IMPORTANT ROLE IN `LM GROWTH DUE TO SATURATION OF THE 3I

&IG  ,ARGE SIZE aAT $ ISLANDS ON THE INTERME

DIATE !G LAYER AND THEIR COALESCENCE A 

-, `LM GROWN ON 3I r SURFACE AT ROOM TEMPERATURE 3CAN AREA !r^b ! 6^b 3

6 )T N! B  -, `LM !r^b !^b 63 6 )T N!

DANGLING BONDS 3INCE THE ACTIVATION EN ERGY FOR SURFACE DI_USION OF !G ADATOMS ON THE INTERMEDIATE LAYER SEEMS TO BE LESS THAN OR EQUAL TO THE THERMAL ENERGY !G ADATOMS CAN EASILY DI_USE RESULTING IN THE FORMATION OF LARGE METALLIC ISLANDS AT ROOM TEMPERA

(a)

(b)

[211]

[121]

[112]

 +ANG (O 0ARK ET AL %42) *OURNAL VOLUME  NUMBER  *ULY 

TURE (ENCE THE AVERAGE SIZE OF ISLAND BE CAME LARGER ABOVE THE DANGLING BOND SATU RATION COVERAGE 4HE FEATURES OF MULTILAYER GROWTH SHOWN IN &IG B ARE ATTRIBUTABLE TO THIS KINETIC MECHANISM 4HE ORIENTATION OF THICK !G ISLANDS SEEMS TO MATCH CLOSELY WITH 3I SUBSTRATE SINCE THE STEP EDGES OF THICK !G ISLANDS ARE COMPOSED OF THE STRAIGHT LINES AND THE NORMAL DIRECTION OF STEP EDGES INDICATED BY ARROWS IN &IG B IS ONE OF SIX DIRECTIONS ;= ;= ;=

;= ;= AND ;= IN 3I CRYSTAL ORI ENTATION

)N CASE OF LOW TEMPERATURE + !G GROWTH ON 3I r INTERLAYER EXCHANGE INCREASED DUE TO THE SMALL ISLAND SIZE AND THE ROUGHNESS OF ISLAND EDGES ;= (OWEVER IN THE PRESENT SYSTEM ISLAND SIZES ARE LARGER AND THE EDGES ARE SMOOTHER THAN THOSE OB SERVED IN LOW TEMPERATURE GROWTH

)6 !G '2/74( /.

3B 4%2-).!4%$ 3I

4HE DEPENDENCE OF 3B OVERLAYER STRUC TURES ON THE 3B COVERAGE AND TEMPERA TURE OF THE 3I r SUBSTRATE HAS BEEN STUDIED EXTENSIVELY ;= ;= 4HESE STUD IES SHOW THAT THE 3B TERMINATED 3I

SURFACE INVOLVES COMPLEX RECONSTRUCTIONS

)N ORDER TO OBTAIN AN 3B MONOLAYER ON 3I  3B WAS DEPOSITED ON A 3I

r SUBSTRATE AT A SUBSTRATE TEMPERATURE OF  ^b# !T A SUBSTRATE TEMPERATURE OF

 ^b# A MONOLAYER OF 3B IS REPORTED TO HAVE THREE ORIENTATIONAL DOMAINS OF r

STRUCTURES AND A DISORDERED r STRUC TURE ;= ;= 4HE INTERACTION OF !G ATOMS WITH 3I ATOMS IS DEPRESSED DUE TO THE PAS SIVATION OF 3I DANGLING BONDS WITH 3B IN THE GROWTH ON 3B TERMINATED SURFACE AND THEREFORE THE AGGLOMERATION OF !G ATOMS OCCURS AT THE SUBMONOLAYER COVERAGE WITH OUT THE WETTING LAYER OF !G

)N THE 34- IMAGES TAKEN FROM 

-, !G `LM GROWN ON A r 3B LAYER CLOSELY PACKED ROUND ISLANDS WERE OBSERVED AS SHOWN IN &IG A  4HE AVERAGE DIAME TER OF ISLANDS IS SMALL AND THE SURFACE IS COMPACTLY COVERED 4HE HEIGHT OF THESE ROUND ISLANDS IS ESTIMATED TO RANGE FROM

 TO  -, HEIGHT OF !G  WHERE THE MONOLAYER STEP HEIGHT IS  ! 3INCE !G^b ISLANDS THINNER THAN  -, ARE UNSTABLE ON 3B TERMINATED 3I SURFACE SMALL ISLANDS OF IRREGULAR HEIGHTS WERE FORMED INITIALLY

4HE VERTICAL SCALE OF THE 34- IMAGE WAS CALIBRATED BASED ON THE BILAYER STEP HEIGHT OF 3I  4HE DENSITY OF SMALL aAT IS LANDS INCREASES WITH INCREASING `LM THICK NESS !T  -, THE SURFACE IS NEARLY `LLED WITH aAT ISLANDS AS SHOWN IN &IG B  4HE FORMATION OF ISLANDS WITH aAT SURFACES CON TINUES UP TO  -, AS SHOWN IN &IG C 

&ROM THE ANALYSIS OF ISLAND HEIGHTS IT IS SUG GESTED THAT THE SMALL ROUND SHAPED ISLANDS OBSERVED IN THE !G `LM OF  -, TEND TO COALESCE INTO aAT !G ISLANDS AT HIGHER COV ERAGES )N FACT AT  -, THESE aAT ISLANDS COALESCED RESULTING IN THE FORMATION OF DEN DRITIC ISLANDS

4HE HEIGHTS OF SUCH ISLANDS ARE MUCH LARGER THAN THE STEP HEIGHT OF !G 

%42) *OURNAL VOLUME  NUMBER  *ULY  +ANG (O 0ARK ET AL 

&IG  34- IMAGES AND LINE PRO`LES ALONG THE WHITE LINE A  -, !G `LM GROWN ON AN 3B TERMINATED

3I SURFACE AT ROOM TEMPERATURE SCAN AREA !r^b ! 6^b 3p 6 )_T N! B  -, !G `LM SCAN AREA !r<sup>b</sup> ! 6<sup>b</sup> 3p )<sub>T</sub> N! C  -, !G `LM SCAN AREA !r^b ! 6^b 3p6 )_T N!

!T  -, ISLANDS WITH HEIGHTS BETWEEN

 AND  ! CORRESPONDING TO  OR  -,S^b OF !G  ARE DOMINANT ALTHOUGH A FEW SHORTER ISLANDS CAN ALSO BE FOUND )N AD DITION THE NUCLEATION OF SMALL ISLANDS ON THE aAT ISLANDS IS OCCASSIONALLY OBSERVED AS SHOWN IN &IG B  &IG C SHOWS THAT FOR A !G `LM OF  -, aAT ISLANDS COALESCED INTO LARGE ISLANDS &URTHERMORE AT  -, A LARGE NUMBER OF aAT !G NUCLEI ARE FORMED ON THE COALESCED aAT ISLANDS AS SHOWN IN

&IG C  4HE STEP HEIGHT OF SMALL ISLANDS NUCLEATED ON aAT ISLANDS IS ALSO ESTIMATED TO BE A MONOLAYER STEP HEIGHT OF !G 

4HE HEIGHT aUCTUATION OF !G ISLANDS IS ESTIMATED TO BE LESS THAN  -, AT 

-, !G `LMS !LTHOUGH THE 3B TERMINATED 3I SURFACE IS NOT COMPLETELY COVERED WITH !G ISLANDS AND THE CRYSTAL ORIENTA TIONS OF !G ISLANDS ALSO DO NOT MATCH WELL

WITH 3I SUBSTRATE EVEN AT  -, ;=

THE TREND TOWARD THE GROWTH OF ATOMICALLY aAT AND UNIFORM !G `LMS WHEN THE SURFAC TANT 3B IS PRESENT IS CLEARLY SHOWN IN THIS WORK

4HE ISLAND DENSITIES OF EACH `LM WITH AND WITHOUT 3B AT ROOM TEMPERATURE AS WELL AS THOSE AT LOW TEMPERATURE ;= ARE SHOWN IN &IG  4HESE INDICATE THAT IN OUR STUDY THE ISLAND DENSITY INCREASED WHEN SURFACTANT WAS USED COMPARED TO THE SAM PLE WITHOUT SURFACTANT 4HIS RESULT SUG GESTS THAT THE SURFACE DI_USION BARRIER OF

!G ATOMS ON AN 3B BU_ER LAYER BE HIGHER THAN THAT ON THE INTERMEDIATE !G MONO LAYER ON CLEAN 3I  SINCE ISLAND DENSITY DEPENDS ON THE SURFACE DI_USION BARRIER OF THE SUBSTRATE 4HE INCREASED ISLAND DEN SITY CAUSES THE HEIGHT OF !G ISLANDS TO BE LIMITED TO  OR  -, BEFORE COALESCENCE OF

600± 10A

14± 1A

600± 10A

17± 1A

530± 10A

21± 1A

(c) (b)

(a)

 +ANG (O 0ARK ET AL %42) *OURNAL VOLUME  NUMBER  *ULY 

&IG 4HE ISLAND DENSITIES OF !G `LMS ON A 3I

SURFACE WITH AND WITHOUT 3B SURFACTANT AT ROOM TEMPERATURE AND AT LOW TEMPERATURE  +

;=

&IG  4HE AVERAGE ISLAND SIZES OF !G `LMS ON A

3I SURFACE WITH AND WITHOUT 3B SURFAC TANT AT ROOM TEMPERATURE AND THOSE OF !G `LM GROWN ON 3I AT LOW TEMPERATURE  + WITHOUT SURFACTANT ;=

THE !G ISLANDS 4HE SMALL !G ISLANDS EVEN TUALLY COALESCE INTO LARGER ONES BEFORE HIGH

$ ISLANDS BEGIN TO GROW

4HE AVERAGE ISLAND RADIUS OBTAINED FROM

!G GROWN ON 3I WITHOUT SURFACTANT AND IN THE LOW TEMPERATURE GROWTH OF

!G3I ;= ARE SHOWN IN &IG  4HE MULTILAYER GROWTH OF !G `LM IN !GCLEAN 3I SYSTEM IS PROBABLY BECAUSE OF THE LOW ISLAND DENSITY )N THE ,%%- STUDY OF

!G GROWTH ON 3B3I BY VAN DER 'ON ET AL ;= A SIMILAR DENSE NUCLEATION EF FECT OF !G ISLANDS WAS OBSERVED WHEN 3B WAS USED AS A SURFACTANT (OWEVER SINCE

!G WAS GROWN AT ELEVATED TEMPERATURE IN THEIR WORK THE ISLAND SIZE WAS MUCH LARGER THAN IN OUR WORK

)N THE GROWTH OF 'E ON 3B TERMINATED 3I PRECOVERED 3B ATOMS DI_USE TO THE SUR FACE VIA AN EXCHANGE MECHANISM 4HIS PRO CESS PLAYS AN IMPORTANT ROLE IN THE LAYER BY LAYER EPITAXIAL GROWTH ;= ;= ;=

(OWEVER NO CLEAR EVIDENCE OF 3B SEGREGA TION AND ITS ROLE IN !G `LM GROWTH ARE FOUND IN THIS WORK 4HE NUCLEATION OF NEW MONOLAYER HEIGHT !G ISLANDS ON THE ALREADY FORMED aAT ISLANDS IN THE  -, HIGH !G

`LM MAY BE CONSIDERED AS AN INDIRECT EVI DENCE OF A SMALL AMOUNT OF 3B SEGREGATION

6 35--!29

7E HAVE OBSERVED THE ATOMICALLY aAT AND UNIFORM GROWTH OF !G ON A 3I

SUBSTRATE TREATED WITH AN 3B SURFACTANT

34- IMAGES SHOWED THAT A ROUGH LAYER WITH ROUND ISLANDS WAS FORMED HAVING A

i MONOLAYER HEIGHT IN THE  -, `LM AND AFTERWARDS ATOMICALLY aAT !G ISLANDS GREW UNIFORMLY ON THE 3B TERMINATED SUR FACE 4HE 34- ANALYSIS OF ISLAND DENSITY

without surfactant with surfactant

low temperature (90 K)[11]

Thickness (ML) 3.0 2.5 2.0 1.5

0.5 1.0 3.5 4.0 4.5 5.0

0.0 7

6

5

4

3

2

1

0 Island density (1012 cm-2)

without surfactant with surfactant

low temperature (90 K)[11]

Thickness (ML) 3.0 2.5 2.0 1.5

0.5 1.0 3.5 4.0 4.5 5.0

0.0 70

60

50

40

30

20

10

0

Average island radius (A)

%42) *OURNAL VOLUME  NUMBER  *ULY  +ANG (O 0ARK ET AL 

AND SIZE IN !G GROWTHS ON CLEAN 3I AND ON 3B TERMINATED 3I SURFACE SUGGESTS THAT THE INCREMENT IN ISLAND DENSITY BE CAUSED BY AN INCREASE OF SURFACE DI_USION BARRIER FOR !G ATOMS ON THE 3B TERMINATED 3I SURFACE 4HIS KINETIC E_ECT OF 3B SEEMS TO PLAY A CRUCIAL ROLE IN THE GROWTH OF aAT AND UNIFORM !G `LM ON 3I ON AN ATOMIC LEVEL AT ROOM TEMPERATURE

6) !#+./7,%$'-%.43

4HIS WORK HAS BEEN SUPPORTED BY THE -INISTRY OF )NFORMATION AND #OMMUNICA TIONS +OREA

2%&%2%.#%3

;= ' ,E,AY - -ANNEVILLE AND 2 +ERN

<#OHESIVE ENERGY OF THE TWO DIMENSIONAL 3I pr !G AND 3I P

 p 2^b !G PHASES OF THE SILVER DEPOSIT SILICON SUB STRATE SYSTEM 3URF 3CI VOL  PP  



;= * ! 6ENABLES * $ERRIEN AND ! 0 *ANSSEN

<$IRECT OBSERVATION OF THE NUCLEATION AND GROWTH MODES OF !G3I  3URF 3CI VOL

 PP   

;= - 3AITOH & 3HOJI + /URA AND 4 (ANAWA

<)NITIAL GROWTH PROCESS AND SURFACE STRUCTURE OF !G ON 3I STUDIED BY LOW ENERGY ION SCATTERING SPECTROSCOPY )33 AND ,%%$ !%3 3URF 3CI VOL  PP   

;= + /URA 4 4AMINAGA AND 4 (ANAWA <%LEC TRONIC PROPERTIES AND ATOMIC ARRANGEMENT OF THE !G3I INTERFACE 3OLID 3TATE #OMM

VOL  PP   

;= & (OUZAY ' - 'UICHAR ! #ROS & 3ALVAN 2 0INCHAUX AND * $ERRIEN <!NGLE RESOLVED PHOTOEMISSION MEASUREMENTS ON !G 3I r

 INTERFACES 3URF 3CI VOL  , , 

;= 4 9OKOTSUKA 3 +ONO 3 3UZUKI AND 4 3AGAWA <3TUDY OF !G3I SUBMONOLAYER INTERFACE 3URF 3CI VOL  PP   

;= % * VAN ,OENEN - )WAMI 2 - 4ROMP AND * & VAN DER 6EEN <4HE ADSORPTION OF !G ON THE 3I r SURFACE AT ROOM TEMPERA TURE STUDIED BY MEDIUM ENERGY ION SCATTERING ,%%$ AND !%3 3URF 3CI VOL  PP  



;= 3T 4OSCH AND ( .EDDERMEYER <)NITIAL STAGE OF !G CONDENSATION ON 3I r 0HYS

2EV ,ETT VOL  PP   *ULY  

 <.UCLEATION AND GROWTH OF #U AND !G ON 3I r * -ICROSCOPY VOL  PP 

 .OVEMBER 

;= - *ALOCHOWSKI AND % "AUER <2ESISTANCE OS CILLATIONS AND CROSSOVER ON ULTRATHIN GOLD `LMS 0HYS 2EV " VOL  NO  PP  

-AY  

;= 2 3CHAD 3 (EUN 4 (EIDENBLUT AND - (EN ZLER <-ETALLIC AND NONMETALLIC CONDUCTIVITY OF THIN EPITAXIAL SILVER `LMS 0HYS 2EV " VOL

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