Construction of Rotating Compensator Ellipsometer Using a MgF 2 Monoplate Retarder and its Application to the Study of GaAs

Construction of Rotating Compensator Ellipsometer Using a MgF ₂ Monoplate Retarder and its Application to the Study of GaAs

Junho Choi · Nilesh S. Barange · Mangesh S. Diware

· Tae Jung Kim ^∗ · Jae Chan Park · Young Dong Kim ^†

Nano-Optical Property Laboratory and Department of Physics, Kyung Hee University, Seoul 130-701, Korea (Received 24 January 2014 : revised 6 March 2014 : accepted 7 March 2014)

We constructed a rotating compensator type ellipsometer (RCE) and applied it to the study of the optical properties of GaAs. In this work, a MgF

2

monoplate retarder was incorporated into the RCE system to avoid the disadvantages of biplates and Berek plates and a photomultiplier tube (PMT) detector was used to effectively detect the signal of light. To demonstrate the high-precision capability of our home made RCE, we present the dielectric function and the critical point (CP) analysis results for GaAs, and we compare the data with those measured by using conventional ellipsometers. This work show that our home made RCE can resolve several CPs near the E

2

CP at room-temperature, which connot be done using conventional ellipsometers.

PACS numbers: 78.20.Ci, 78.55.Cr

Keywords: Ellipsometry, GaAs, RCE, Monoplate

MgF ₂ Monoplate | ºX N ËM õ u §  “ Ó Þ” X ¢ > H ¹ Å| ºX N ËM ] k ù  Ì ¦ R  Å° Ë ÑÄ Z ØV ÄM 8 ý < gX c l õ m Í GaAs Ž ì ŏ Œ; c 6 ” X ¢ “ Ö «“ Ó Þ

L

|+ Ö <‡ Ú · Nilesh S. Barange · Mangesh S. Diware ·  ™ »? ^ ï B ^∗ · ƒ ‘ š< ¾ 6 Ò ·  ™ »* å  ò 6 B ^†

 â

 B@ /† < Ɠ § Ó ü t o † < Æõ  x 9 
” ¸ F  gÓ ü t$ í ƒ  ½ ¨z  ´, " fÖ  ¦ 130-701

(2014¸   1 Z 4 24{ 9  ~ à Î6 £ §, 2014¸   3 Z 4 6{ 9  à º& ñ ‘ : r ~ à Î6 £ §, 2014¸   3 Z 4 7{ 9  > F  S X ‰& ñ )

‘ :

r ƒ  ½ ¨\ " f  H  r„  ˜ Ð& ñ l + þ A  " é ¶¼ # F  gì  r$ 3 l  (Rotating Compensator Ellipsometer, RCE) \  ¦ ] j



Œ

• “ ¦ ] j Œ •  ) a RCE \  ¦ GaAs _  F  g: £ ¤$ í ƒ  ½ ¨\  & h 6   x % i  . Biplate (4 Ÿ ¤8 £ x ½ ¨› ¸) ü < Berek plate ˜ Ð& ñ l

_  é ß –& h [ þ t`  ¦ x  l  0 A # Œ MgF

2

monoplate ( é ß –8 £ x ½ ¨› ¸) ˜ Ð& ñ l   6   x ÷ &% 3 “ ¦, ´ òõ & h Ü ¼– Ð y n C_ 

’

   ñ\  ¦  Ž Ø  ¦ l  0 A # Œ F  g„   7 £ x C  › ' a (photomultiplier tube)  Ž Ø  ¦ l   6   x ÷ &% 3  . “ ¦& ñ x 9  8 £ ¤& ñ & ñ x 9

• ¸\  ¦ S X ‰ “   l  0 AK " f GaAs _  Ä »„  Ö  ¦ † < Êà º\  ¦ 8 £ ¤& ñ “ ¦, „  s & h [ þ t`  ¦ ì  r$ 3  % i Ü ¼ 9, l ” > r _   " é ¶

¼

# F  gì  r$ 3 l \  ¦ : Ÿ x K  % 3 # Q · p   õ ü < q “ § % i  . Õ ª   õ  l ” > r _   " é ¶¼ # F  gì  r$ 3 l [ þ t – Ѝ  H ì  r o  Ô  ¦  0

p

x ô  Ç E

2

„  s & h  % ò % i  Â Ò   H _  „  s & h [ þ t`  ¦  © œ“ : r \ " f ì  r$ 3 ½ + É Ã º e ” % 3  .

PACS numbers: 78.20.Ci, 78.55.Cr

Keywords:  " é ¶¼ # F  gì  r$ 3 Z O , GaAs, RCE, Monoplate

∗

E-mail: [email protected],

^†

E-mail: [email protected]

371

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License

(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any

medium, provided the original work is properly cited.

I. " e  ] Ø



" é ¶¼ # F  gì  r$ 3 Z O  (Spectroscopic Ellipsometry) “ É r Ó ü t| 9  _

 F  g : £ ¤$ í x 9  ~ à Ì} Œ •_  ¿ ºa  1 p x`  ¦   & ñ   H X < e ” # Q B Ä º Ä » 6

 

x ô  Ç ~ ½ ÓZ O Ü ¼– Ð+ ‹,  r„   Ž F  g  + þ A  " é ¶¼ # F  gì  r$ 3 l  (Rotat- ing Analyzer Ellipsometer, RAE) ü <  r„  ¼ # F  g l + þ A  " é ¶

¼

# F  gì  r$ 3 l  (Rotating Polarizer Ellipsometer, RPE)  Õ

ª 1 l x î ß – V , o  s 6   x ÷ &# Q M ® o   [1,2]. t ë ß – 8 £ ¤& ñ 5 Å q • ¸ x 9 

&

ñ S X ‰ • ¸\  ¦ Z  } s l  0 A # Œ RAE, RPE \ " f  r„  ˜ Ð& ñ l  + þ

A  " é ¶¼ # F  gì  r$ 3 l  (Rotating Compensator Ellipsome- ter, RCE) – Ð 8 £ ¤& ñ l Õ ü t s  µ 1 ϲ ú ˜÷ &# Q M ® o   [3,4]. RCE \ 

"

f  H RAE, RPE ü < ² ú ˜o  ¼ # F  g l  (Polarizer) ü <  Ž F  g   (Analyzer) \  ¦ “ ¦& ñ “ ¦ ˜ Ð& ñ l  (Compensator)  “ ¦5 Å q Ü

¼– Ð  r„  † < ÊÜ ¼– Ð+ ‹ r « Ñ\  ì ø Í   ) a y n C_  0 A © œ`  ¦ ˜ Ð& ñ K Å Ò

#

Q þ j7 á x& h Ü ¼– Ð  Ž Ø  ¦ ÷ &  H y n C_  [ jl \  Æ Ò& h “   Å Ò à º_ 

&

ñ ˜ Ð\  ¦ ] j/ B N K ï  r  . s X O >  r « Ñ\  › ' a ô  Ç Æ Ò& h “   Ó ü t o 

&

h

 & ñ ˜ Ð\  ¦ % 3 `  ¦ à º e ”   H  © œ& h Ü ¼– Ð “  K , RAE ü < RPE \ 

"

f 4 Ÿ ¤ ™ è ì ø Í > à ºq  ˜ ρ = ˜ r p /˜ r s = tan Ψe ^i∆ – РÒ'  % 3 > 

÷

&  H sin ∆ _   Ҡ ñ\  ¦ ó ø ÍZ > ½ + É Ã º \ O % 3 ~   ë  H ] j\  ¦ K   ½ + É Ã º e ”

>   ) a   (˜r p , ˜ r s   H y Œ •y Œ • { 9  €  \  @ /ô  Ç y n C_  p $ í ì  r, s

$ í

ì  r _  4 Ÿ ¤ ™ è ì ø Í > à º\  ¦ _ p ô  Ç ). s   H  " é ¶¼ # F  gì  r$ 3 

\

" f % 3 >  ÷ &  H   à º (Ψ, ∆) _  8 £ ¤& ñ # 3 0 A\  ¦ 0 ≤ Ψ ≤ 90 ^◦ , 0 ≤ ∆ ≤ 360 ^◦ – Ð S X ‰  © œr ( ” Ü ¼– Ð+ ‹ r « Ñ\ " f ì ø Í   ) a y n Cs 

| 9  à º e ”   H 0 p x ô  Ç — ¸Ž  H ¼ # F  g  © œI \  @ /ô  Ç & ñ ˜ Ð\  ¦ · ú ˜



? /  H  כ s  0 p x K f ” `  ¦ _ p ô  Ç .

l

” > r _   " é ¶¼ # F  gì  r$ 3 l \  ˜ Ð& ñ l – Ð+ ‹ V , o   6   x ÷ &“ ¦ e ”

  H biplate (4 Ÿ ¤8 £ x ½ ¨› ¸) ˜ Ð& ñ l ü < Berek plate ˜ Ð& ñ l   H y

Œ

•y Œ • 8 £ ¤& ñ   õ \  % ò † ¾ Ó`  ¦ p u   H “ ¦Ä »ô  Ç ë  H ] j& h [ þ t`  ¦  t

“ ¦ e ”  . Ä º‚   biplate   H ¿ º > h_  plate  ”   fast axis _

 à ºf ”  & ñ § > = © œI  ¢ - a# 4  t  · ú § 
 plate  s _  / B N l  8

£

x Ü ¼– Ð “  K , biplate _  t ƒ  y Œ • † < Êà º δ(E)  “ ¦Å Ò à º _

 כ ¹1 l x`  ¦ ˜ Ðs >  ÷ &# Q 8 £ ¤& ñ   õ \   H % ò † ¾ Ó`  ¦ p u >   ) a



 [5], [6]. ¢ ¸ô  Ç Berek plate _   â Ä º\   H biplate  ”   ë

 H ] j& h “ É r \ O t ë ß –, ”  ' Ÿ    H y n C_   ⠖ Ð\  ¦  Ë ¨  H ë  H ] j& h  (beam displacement) `  ¦ t “ ¦ e ”   [7]. s  Qô  Ç ë  H ] j& h  [

þ

t – Ð “   # Œ monoplate (é ß –8 £ x ½ ¨› ¸) ˜ Ð& ñ l  biplate ü <

Berek plate _  @ /î ß –Ü ¼– Ð+ ‹ # Œ t “ ¦ e ”   [8].

‘

: r ƒ  ½ ¨\ " f  H MgF 2 monoplate ü < F  g„   7 £ x C  › ' a (photomultiplier tube, PMT)  Ž Ø  ¦ l \  ¦  6   x   H  { 9  _

 RCE \  ¦ ] j Œ • % i  . { 9  y Œ •“ É r 69.76 ^◦ – Ð “ ¦& ñ ÷ &# Q e ”  Ü

¼ 9, 8 £ ¤& ñ ì  rF  g% ò % i “ É r 1.5 - 6.0 eV s  . ¢ ¸ô  Ç ‘ : r ƒ  ½ ¨

\

" f ] j Œ •  ) a RCE _  8 £ ¤& ñ 0 p x§ 4 s  Ä ºÃ º† < Ê`  ¦ ˜ Ðs l  0 A 

#

Œ, GaAs _  8 £ ¤& ñ x 9  ì  r$ 3   õ \  ¦ l ” > r _   " é ¶¼ # F  gì  r$ 3  l

\  ¦ : Ÿ x K  % 3 # Q · p   õ ü < q “ § % i  .

Fig. 1. (a) A brief schematic of the single rotating com- pensator ellipsometer in the PSC _r (ω _c )A configuration.

(b) The design of the monoplate compensator. The rota- tion axis, surface normal, propagation of light and c-axis of the monoplate compensator are represented by ˆ ω, ˆ n,

~ k and ˆ c, respectively.

II.  Ì ¦ R  Å° Ë ÑÄ Z ØV ÄM  O  ß Ã Å õ m Í T Â ] Ø

Figure 1(a) \ " f  H PSC r (ω c )A ½ ¨$ í `  ¦ ”   RCE _  ç ß –

| Ä

Ìô  Ç ½ ¨$ í • ¸\  ¦ ˜ Ð# ŒÅ ғ ¦ e ”  . ‘ : r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE

\

 ¦ ½ ¨$ í “ ¦ e ”   H F  g † < Æ& h   Ҿ ¡ §[ þ t`  ¦ í  H " f@ /– Ð
\ P   

€

 , 75 W ] j 7 HÏ þ ›á Ô, ì  rF  g l , MgF ² rochon ¼ # F  g l , r « Ñ Û

¼_ …s t , MgF ² monoplate ˜ Ð& ñ l , MgF ² rochon  Ž F  g



, PMT  Ž Ø  ¦ l – Ð ½ ¨$ í ÷ &# Q e ”  . Fig. 1(b)\ " f  H  6   x

 )

a MgF 2 monoplate _  n  “  õ  { 9     H y n Cõ _  s  © œ

&

h “   & ñ § > = © œI \  ¦ ˜ Ð# ŒÅ ғ ¦ e ”  . Monoplate _  ¿ ºa   H 500 µm s “ ¦ c-axis   H plate ³ ð€   Z O ‚  \  @ / # Œ €  • 9 ^◦ (θ _c ) & ñ • ¸ l Ö  ¦ # Q4 R e ”  . 620 nm   © œ_  y n Cs  ‘ : r ƒ  ½ ¨\ 



6   x ) a monoplate \  ¦ : Ÿ x õ ô  Ç  & ñ ½ + É M :, > í ß –  ) a beam displacement  o   H €  • 1.3 µm – Ð Á ºr  | ¨ c ë ß –
p u _   Œ •“ É r

° ú

כ`  ¦ ° ú   H  . > í ß –\ " f 620 nm   © œ_  y n C\  @ /ô  Ç MgF 2

_

 Ï ã J] X Ö  ¦“ É r n o = 1.37718, n e = 1.38897 s   6   x ÷ &% 3   [9]. Monoplate _  beam displacement  o  > í ß –  õ   H ë

 H‰  ³ [8] \ " f q 5 p w ô  Ç › ¸|  \  Berek plate  ˜ Ðs   H >  í

ß –  õ  22.9 µm \  q K  F  g  © œy   Œ •   H  כ `  ¦ · ú ˜ à º e ” “ ¦,

s

  H monoplate   " é ¶¼ # F  gì  r$ 3 l \   6   x ÷ &  H ˜ Ð& ñ l 

–

Ð  © œ & h ½ + Ë    H  כ `  ¦ _ p ô  Ç . Monoplate \  ¦  r„   r

&  Šҍ  H  r„  — ¸'   H 58 Hz _  l > & h “    r„   Å Ò à º

–

Ð  r„  ô  Ç . Fig. 1(b)_  s  © œ& h “    â Ä ºü < ² ú ˜o , “ ¦5 Å q Ü ¼

–

Ð  r„     H monoplate ü < { 9     H y n Cõ _  & ñ § > = © œI 

#

QF M
>   ) a  €   ˆ ω, ˆ n, ~ k  { 9 u  t  · ú §>  ÷ &“ ¦ s   H 8 £ ¤

&

ñ   õ \   H š ¸À Ó\  ¦ µ 1 ÏÒ q tr †   .   " f 8 £ ¤& ñ „   ˜ Ð& ñ l  _

 F  g † < Æ& h  & ñ § > =õ & ñ s  B Ä º ×  æ כ ¹  . þ j7 á x& h Ü ¼– Ð PMT

 Ž

Ø  ¦ l \  _ K  8 £ ¤& ñ  ) a y n C_  ’    ñ  H PMT  r– Ð\  Ÿ í† < ʝ ) a

$

Å Ò  : Ÿ x õ  € 9 ' ü < & ñ À Ó  r– Ð\  ¦  u >  ÷ &“ ¦, ’    ñ @ /

”

¸s Ý ¼ q Ö  ¦ s  þ j& h  o  ) a „  · ú š ’    ñ– Ð  7 >   ) a  . s  M

: ] j 7 H Ï þ ›á Ô\ " f µ 1 ÏÒ q t   H y n C_  [ jl    © œ\     ² ú ˜



  Ž Ø  ¦ ÷ &  H „  · ú š ’    ñ• ¸ y n C_    © œ\      Ø Ô>   ) a



.   " f y n C_  ’    ñ\  ¦ 7 £ x; Ÿ ¤ l  0 AK  PMT \  K Å Ò



 H “ ¦„  · ú š`  ¦  1 l x › ¸] X  (regulation mode) # Œ,  Ž Ø  ¦ ÷ &  H

“

§À ӄ  · ú š’    ñ[ þ t _  f ” À ӄ  · ú šs  þ j@ /ô  Ç { 9 & ñ >  Ä »t ÷ &

•

¸2 Ÿ ¤ † < ÊÜ ¼– Ð+ ‹ ” ¸s Ý ¼ Y U6 \ š`  ¦ þ j™ è or †   . PMT  r– Ð

\

" f „  · ú š ’    ñ– Ð   ¨ 8 Š ) a F  g„  À Ó ’    ñ  H  ± ú ˜– ÐÕ ª-n t  _ O

   ¨ 8 Š l  (Analog-Digital Converter, ADC) \  ¦ : Ÿ x K  n  t

_ O  ’    ñ– Ð  Ÿ ÷ ¶  . ADC – Ð { 9 § 4  ) a y n C_  [ jl  ’    ñ  H

˜

Ð& ñ l   r„     H Å Ò à º ω _  † < Êà º + þ AI \  ¦ ° ú >   ) a  .

PSCA-RCE + þ A_   â Ä º, y n C_  [ jl \  › ' a ô  Ç r Û ¼% 7 › „  ² ú ˜

†

< Êà º (system transfer function)  H d ”  (1) õ  ° ú  s  ³ ð‰ & ³ ) a



.

I = I 0

2



(|˜ r _p ⁰ | ² + |˜ r _s ⁰⁰ | ² ) + cos ² δ

2 {(|˜ r ⁰ _p | ² − |˜ r ⁰⁰ _s | ² )cos 2A + 2Re[˜ r _p ⁰ r ˜ ⁰⁰ _s ] sin 2A}

− 2Im[˜ r ⁰ _p r ˜ _s ⁰⁰ ]sin δsin(2C − 2A) + sin ² δ

2 {(|˜ r _p ⁰ | ² − |˜ r ⁰⁰ _s | ² )cos(4C − 2A) + 2Re[˜ r _p ⁰ r ˜ ⁰⁰ _s ] sin(4C − 2A)}



(1)

=dc + a 2 cos(2ωt) + b 2 sin(2ωt) + a 4 cos(4ωt)

+ b 4 sin(4ωt) (2)

=dcα 2 cos(2ωt) + β ₂ sin(2ωt) + α ₄ cos(4ωt)

+ β ₄ sin(4ωt)  (3)

d ”

 (1) \ " f ˜r p ⁰ = ˜ r _p cos P , ˜ r _s ⁰⁰ = ˜ r _s sin P s  9 C   H r « Ñ_ 

³

ð€   Z O ‚  \  @ /ô  Ç ˜ Ð& ñ l _  fast-axis _  y Œ •• ¸ (C = ωt)

\

 ¦ _ p  “ ¦ P, A   H y Œ •y Œ • ¼ # F  g l ü <  Ž F  g  _  y Œ •`  ¦ _  p

ô  Ç . d ”  (1) `  ¦  8¹ ¡ ¤ ç ß –é ß –ô  Ç + þ AI – Ð & ñ o  >  ÷ &€  , d ”

 (2), (3) _  + þ AI – Ð & ñ o   ) a  . # Œl " f α 2 = a ₂ /dc, β 2 = b 2 /dc, α 4 = a 4 /dc, β 4 = b 4 /dc – Ð & ñ _   ) a  . { 9 § 4 

Fig. 2. Dependence of the derivatives of the normalized Fourier coefficients on retardance angle for tan Ψ = 1 and

∆ ranging from 0 to 90 ^◦ in steps of 10 ^◦ . (a) Derivatives with respect to Ψ, and (b) derivatives with respect to ∆.

 )

a y n C_  [ jl  ’    ñ  H d ”  (2), (3) õ  ° ú  s  ˜ Ð& ñ l   r„  

  H 5 Å q • ¸ ω \    É r É Òo \  † < Êà º + þ AI \  ¦ ˜ Г   .   

"

f { 9 § 4  ) a ’    ñ  H É Òo \    ¨ 8 Š`  ¦  u >  ÷ &“ ¦, s \  ¦ : Ÿ x K

 r « Ñ\  › ' a ô  Ç Ó ü t o & h “   & ñ ˜ Ð\  ¦ ] j/ B N K Šҍ  H É Òo \  >  Ã

º α 2 , β 2 , α 4 , β 4 \  ¦ % 3 >   ) a  . % 3 # Q · p É Òo \  > à º[ þ t“ É r r

« Ñ\  › ' a ô  Ç ì ø Í > à º“   ˜ r p , ˜ r s \  @ /ô  Ç & ñ ˜ Ð\  ¦ { Œ ™“ ¦ e ” 

“

¦, s \  ¦ : Ÿ x K  r « Ñ_  4 Ÿ ¤ ™ èì ø Í > à ºq  ˜ ρ = ˜ r _p /˜ r _s \  ¦ % 3 > 

 )

a  . ‘ : r ƒ  ½ ¨\ " f  H RCE \  ¦ : Ÿ x K  8 £ ¤& ñ  ) a É Òo \  > à º

\

 ¦ q ‚  + þ A þ j™ è 5 p xZ O  (nonlinear least-square method)

`

 ¦  6   x # Œ (Ψ, ∆) \  ¦ % 3 # Q · p Ê ê, d ”  (4) _  › ' a > d ” `  ¦ : Ÿ x K

 $ í Ä »„  Ö  ¦ † < Êà º (pseudodielectric function) \  ¦ > í ß – ô

 Ç .

hi =h 1 i + ih 2 i = sin ² φ

"

1 + tan ² φ  1 − ˜ ρ 1 + ˜ ρ

 ² # (4)

#

Œl " f φ   H r « Ñ\  { 9  ÷ &  H y n C_  { 9  y Œ •`  ¦ _ p ô  Ç .

d ”

 (1) “ É r ‘ : r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE _  : £ ¤$ í `  ¦ ¸ ú ˜ ˜ Ð# Œ Å

ғ ¦ e ”  . Ä º‚   δ = 180 ^◦ { 9  M : 2ω $ í ì  r s    f ” `  ¦ S X ‰

“

 ½ + É Ã º e ” “ ¦, δ(E)  y n C_    © œ\  _ ” > r   H † < Êà ºs l  M

:ë  H \  RCE _  l ‘ : r ½ ¨$ í „  \  t ƒ  y Œ • † < Êà º δ(E) \  ¦ · ú ˜



? /  H 1 l qw n & h “   õ & ñ `  ¦  5 g  ô  Ç . t ë ß –, ‘ : r  7 Hë  H

\

" f  H δ(E) \  ¦ % 3 # Q? /  H õ & ñ “ É r Ò q t| Ä Ì % i  .

Fig. 3. The pseudodielectric function spectra hi for an oxidized GaAs measured by home-made RCE from 1.5 to 6.0 eV at the angle of incidence 69.76 ^◦ .

Figure 2 \ " f  H ˜ Ð& ñ l _  t ƒ  y Œ •s  180 ^◦ { 9   â Ä º 8 £ ¤& ñ

 

õ – Ð % 3 >  ÷ &  H y Œ • É Òo \  > à º[ þ t _  Ψ ü < ∆ \  @ /ô  Ç    y

Œ

™• ¸ 0 s  ÷ &  H  כ `  ¦ S X ‰ “  ½ + É Ã º e ”  . t ë ß –, ¿ º > h_ 

>

à º\  @ /ô  Ç   y Œ ™• ¸ 0 s  ÷ & 8 • ¸
 Qt  ¿ º α ⁴ , β 4

\

 ¦ : Ÿ x K  ì  r$ 3 \  € 9 כ ¹ô  Ç (Ψ, ∆) \  ¦ % 3 # Q? /  H  כ s  0 p x 



.

III. + s ÇÊ Ý õ m Í ‚ º8 ý

‘

: r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE _  8 £ ¤& ñ & ñ x 9 • ¸_  Ä ºÃ º† < Ê`  ¦ 7

£ x" î l  0 A # Œ, ³ ð€   í ß – o8 £ x s  ” > r F    H GaAs _  Ä »

„

 Ö  ¦ † < Êà º\  ¦ 8 £ ¤& ñ “ ¦ „  s & h [ þ t`  ¦ ì  r$ 3  % i  . Fig. 3  H

‘

: r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE \  _ K  8 £ ¤& ñ  ) a í ß – o8 £ x s  ” > r F

   H GaAs _  Ä »„  Ö  ¦ † < Êà º\  ¦ ˜ Ð# Œï  r  . ×  æ^ o ?÷ &# Q e ” 



 H „  s & h [ þ t`  ¦ ì  r" î >  S X ‰ “   l  0 A # Œ 8 £ ¤& ñ  ) a Ä »„   Ö

 ¦ † < Êà º\  ¦ s > p ì  r ô  Ç Ê ê, s    õ \  ¦ ³ ðï  r K $ 3   ½ ™× ¼Ì “ s

³

ð‰ & ³`  ¦ : Ÿ x K  x h A`  ¦ ”  ' Ÿ  % i   [10]. Fig. 4  H ‘ : r ƒ  ½ ¨

\

" f ] j Œ •  ) a RCE ü < l ” > r _   " é ¶¼ # F  gì  r$ 3 l  (VASE, J.

A. Woollam Co., Inc.) \  _ K " f 8 £ ¤& ñ  ) a GaAs _  Ä »„   Ö

 ¦ † < Êà º s > p ì  r   õ  x 9  x h A  õ \  ¦ \  -t  % ò % i  4.25 - 5.35 eV \ " f ˜ Ð# ŒÅ ғ ¦ e ”  . q “ §\   6   x ô  Ç l ” > r  © œq 



 H RAE  { 9 Ü ¼– Ð  1 l x Ü ¼– Ð ˜ Ð& ñ l 0 p x`  ¦ à º' Ÿ    H Berek plate ü < PMT  Ž Ø  ¦ l \  ¦  6   x ô  Ç . 8 £ ¤& ñ › ¸| “ É r \  -t  ç

ß –   0.00902 eV, 200 Revs/Measurement – Ð 1 l x{ 9 ô  Ç › ¸

|

 \  8 £ ¤& ñ % i Ü ¼ 9, 8 £ ¤& ñ  ) a Ä »„  Ö  ¦ † < Êà º\  ¦ s > p ì  r ô

 Ç Ê ê\  1 l x{ 9 ô  Ç 11-points linear filtering algorithm `  ¦ & h  6

 

x % i   [11]. ì  r$ 3   õ \  ¦ : Ÿ x K  ì  r o ô  Ç y Œ • „  s & h [ þ t \ 

@

/ô  Ç " î " î “ É r ˜ Г ¦  ) a GaAs _   ½ ™× ¼> í ß –  õ \  ¦ ‚ à Л ¸ % i 



 [12].

Fig. 4. Open circles: data for d ² h 1 i/dE ² . Solid and dashed lines: best fits to the data for d ² h 1 i/dE ² and d ² h 2 i/dE ² . (a) The results for home-made RCE and (b) the results for conventional ellipsometer.

0

A   õ \  ¦ : Ÿ x K  ‘ : r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE  l ” > r _   

"

é

¶¼ # F  gì  r$ 3 l \  q K   Å Ò 8 A# Qè ß – & ñ x 9 • ¸\  ¦ t “ ¦ e ” 



  H  כ `  ¦ 7 £ x" î ½ + É Ã º e ” % 3  . ] j Œ •  ) a RCE \  _ K  8 £ ¤& ñ

 )

a Ä »„  Ö  ¦ † < Êà º  H ” ¸s Ý ¼ Y U6 \ šs  ± ú   8 ú x 4 > h_  „  s & h  E 0 0 , E 0 0 + ∆ 0 0 , E 2 (X), E 2 (Σ) `  ¦ ì  r$ 3 K  è ­ q à º e ” % 3 t ë ß –, l

” > r _   " é ¶¼ # F  gì  r$ 3 l – Ð 8 £ ¤& ñ  ) a Ä »„  Ö  ¦ † < Êà º  H 4.55 - 4.95 eV % ò % i \ " f_  ” ¸s Ý ¼ Y U6 \ šs  Z  }   š ¸f ”  3> h_  „   s

& h  E ₀ ⁰ , E 0 0 + ∆ 0 0 , E 2 (Σ) ë ß –`  ¦ ì  r$ 3 K  è ­ q à º e ” % 3  . ¢ ¸ ô

 Ç l ” > r \  ˜ Г ¦  ) a GaAs _   © œ“ : r _  › ¸| \ " f 4.25 - 5.35 eV ? /\  š ¸f ”  2> h_  „  s & h ë ß –`  ¦ ˜ Г ¦ô  Ç   õ ü < q “ § 

€

  [13], ‘ : r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE \  ¦ : Ÿ x K  ×  æ^ o ?÷ &# Q e ”   H



8 ´ ú §“ É r „  s & h [ þ t`  ¦ ì  r o ½ + É Ã º e ” % 3  . s % ƒ! 3  ‘ : r ƒ  ½ ¨

\

" f ] j Œ •  ) a RCE  l ” > r _    É r  " é ¶¼ # F  gì  r$ 3 l \  q  K

 ± ú “ É r ” ¸s Ý ¼ Y U6 \ š`  ¦ ˜ Ðs   H s Ä »  H ì  rF  g l _  Z  }“ É r ì  r K

0 p x, monoplate _   6   x, PMT \ " f  Ž Ø  ¦ ) a ’    ñ @ / ” ¸ s

Ý ¼ q Ö  ¦ þ j& h  o, RCE r Û ¼% 7 ›\   6   x ) a F  g  Ҿ ¡ §[ þ t _  & ñ

§ >

=  © œI  1 p x # Œ Q t  כ ¹“  [ þ t s  e ”  .    : r& h Ü ¼– Ð ‘ : r ƒ  

½

¨\ " f ] j Œ •  ) a RCE  l ” > r _   " é ¶¼ # F  gì  r$ 3 l [ þ t \  q  K

 Ä ºÃ ºô  Ç & ñ x 9 • ¸\  ¦ f ” `  ¦ GaAs _  Ä »„  Ö  ¦ † < Êà º ƒ  ½ ¨

\

 ¦ : Ÿ x K " f ˜ Ð% i  .

IV. + s Ç Â ] Ø

‘

: r ƒ  ½ ¨\ " f  H PMT  Ž Ø  ¦ l ü < l ” > r \  ˜ Ð& ñ l – Ð V , o  s

6   x ÷ &~   biplate ü < Berek plate _  ë  H ] j& h [ þ t`  ¦ x  l  0

A # Œ MgF 2 monoplate \  ¦  6   x ô  Ç “ ¦& ñ x 9  RCE \  ¦ ] j



Œ

• % i  . > í ß –  õ \  ¦ : Ÿ x K , ‘ : r ƒ  ½ ¨\ " f ] j Œ •  ) a RCE

 8 £ ¤& ñ K ? /  H É Òo \  > à º[ þ t s   " é ¶¼ # F  gì  r$ 3    à º[ þ t“   (Ψ, ∆) \  ˜ Ðs   H   y Œ ™• ¸  r„  ˜ Ð& ñ l _  t ƒ  y Œ •\  _ ” > r

  H : £ ¤$ í `  ¦ ˜ Ð% i  . ] j Œ •  ) a RCE \  _ K  8 £ ¤& ñ  ) a GaAs Ä

»„  Ö  ¦ † < Êà º_  s > p ì  r ì  r$ 3   õ \  ¦ l ” > r \  ˜ Г ¦  ) a    õ

 x 9  l ” > r _   " é ¶¼ # F  gì  r$ 3 l \  _ K  8 £ ¤& ñ  ) a   õ ü <_  q

“ §\  ¦ : Ÿ x K " f & ñ x 9 • ¸_  Ä ºÃ º† < Ê`  ¦ 7 £ x" î % i  . : £ ¤ y  4.0 - 5.5 eV % ò % i \ " f_  ± ú “ É r ” ¸s Ý ¼ Y U6 \ š– Ð “  K  l ” > r _   

"

é

¶¼ # F  gì  r$ 3 l [ þ t – Ѝ  H ƒ  ½ ¨ Ô  ¦ 0 p xÙ þ ¡~    © œ“ : r \ " f_  ×  æ

^ o

?÷ &# Q e ”   H „  s & h [ þ t \  @ / # Œ  H ƒ  ½ ¨ 0 p x$ í `  ¦ ˜ Ð# Œ Å

Ò% 3  .

P

c p 8 ý ò k >

s

  7 Hë  H“ É r 2013¸  • ¸ & ñ Â Ò (p A ‚ ½ ӛ ¸õ † < Æ Ò)_  F " é ¶ Ü ¼

–

Ð ô  Dz D Gƒ  ½ ¨F é ß –_  t " é ¶`  ¦ ~ à Î  à º' Ÿ  ) a ƒ  ½ ¨e ”  (2013- 016297).

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