Fe ~ ¾W È c Ü R n-GaAs8 ý Photoreflectance — ¤V R Ë Ž ì ŏ Œ

Fe ~ ¾W È c Ü R n-GaAs8 ý Photoreflectance — ¤V R Ë Ž ì ŏ Œ

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% ò

z Œ ™@ /† < Ɠ § s õ @ /† < Æ Ó ü t o † < Æõ ,  â í ß – 712-749

' Ö <* å r )

LG z  ´à ԏ : r ƒ  ½ ¨™ è, ½ ¨p  730-350 (2004¸   5 Z 4 20{ 9  ~ à Î6 £ §)

n-GaAs ³ ð€  0 A\  Fe š ¸% i  Ê ê \ P % ƒo   ) a Ò  re  ¦ \  @ /K  PR ~ ½ ÓZ O Ü ¼– Ð › ¸  % i  . Ò  re  ¦“ É r 10 ì  rç ß – 300 \ " f 600

C  t  \ P % ƒo  ô  Ç Ò  re  ¦ õ  300

C \ " f 10\ " f 60 ì  rç ß – \ P % ƒo  ô  Ç Ò  re  ¦ – Ð ï  r q  % i  .

10 ì  rç ß – 300 \ " f 600

C  t  \ P % ƒo  ô  Ç Ò  re  ¦_  PR’    ñ\ " f, n-GaAs_   â Ä º  H 49 %“  X < q K  Fe\  ¦

³

ð€   š ¸% i r †   n-GaAs  H 66 % – Ð  8 ß ¼ . s   H Fe  ³ ð€   š ¸% i  ) a r « Ñ\ " f Fe \ P % ƒo  ´ òõ – Ð “   K

 ? / Җ Ð S X ‰í ß –(diffusion)H † d \  _ K " f Fe

 s “ : r Ü ¼– Ð ÷ &Ù ¼– Ð “  K " f ×  æ$ í % 3 ! s s'   Œ •6   x`  ¦ l  M : ë

 H Ü ¼– Ð  « Ñ  ) a  .

PACS numbers: 73

Keywords: photoreflectance, Fe, GaAs

I. " e  ] Ø

F 

g  › ¸ ì  rF  gZ O (photoreflectance; PR)“ É r ì ø ͕ ¸^ ‰_  Ó ü t

$ í

`  ¦ › ¸    H q  õ  q ] X 8 ú ¤& h “   ~ ½ ÓZ O ×  æ_  
s  9, þ

j  H \  ´ ú §s  8 £ ¤& ñ   H ~ ½ ÓZ O ×  æ_  
s   [1]. ¢ ¸ô  Ç r 

«

Ñ_  ? /Â Ò „  l  © œõ  é ß –5 Å q ) a Y Us 4 R c ” \  _ K  Ò q t$ í  ) a ì ø Í



Ö  ¦    o\  ¦ 8 £ ¤& ñ † < ÊÜ ¼– Ð+ ‹ F  g† < Æ  © œÃ º_  3  p ì  r \  › ' a > 

 )

a \ Vo   9 “ ¦ì  r K 0 p x_  Û ¼& 7 ˜à Ô! 3 `  ¦ % 3 `  ¦ à º e ” Ü ¼ 9, ì ø Í

•

¸^ ‰_  ³ ð€  õ  ? / Ò © œI , Õ ªo “ ¦  ×  æ € ª œ  Ä ºÓ ü t x 9  œ í

 

  ½ ¨› ¸ 1 p x_  ƒ  ½ ¨\  V , o  s 6   x ) a   [2]. ¢ ¸ô  Ç s  ~ ½ Ó Z O

“ É r r « Ñ_   ½ ™× ¼Ì “ s ˜ Ð  Z  }“ É r \  -t _  f  ¨ à º– Ð “  K  ³ ð

€ 

   H % ƒ\  F  g H o # Q[ þ t s  Ò q t$ í , F   ½ + Ë 1 p x H o # Q_  ¹ ¡ §f ”  e ”

`  ¦    H X < B Ä º ×  æ כ ¹  . Õ ªo “ ¦   › ¸÷ &# Qt   H “   



 H { 9   F  g_    © œ, r « Ñ_  “ : r • ¸, “  ô  Ç 6 £ x§ 4 ,  l  © œ x 9 

„ 

l  © œ 1 p x s  9 é ß –Ò  oF  g_  “ §À Ӓ    ñ\  ¦ r « Ñ? /\  { 9  r v 

€ 

, r « Ñ_  „  l  © œ“ É r y Œ ™™ è÷ &# Q F  g† < Ɠ   \  ¦    or †   .

s

M : s     o| ¾ ӓ É r F  g† < Æ “   _  p ì  r + þ AI \  ¦ t  9 s \  ¦ 8

£

¤& ñ   H  כ s  PRZ O s   [3].

GaAs  H III-V7 á ¤  o½ + ËÓ ü t ì ø ͕ ¸^ ‰– Ð" f F  g ™ è  ÷  rë ß –  m 



 “ ¦5 Å q ™ è – Ð+ ‹_  6 £ x6   x$ í _  7 £ x – Ð “  K  Å Ò3 l q~ à Γ ¦ e ” 



. ¢ ¸ô  Ç GaAs\  Ô  ¦í  HÓ ü t ' ‘ \  @ /ô  Ç r « Ñ_  : £ ¤$ í ƒ  ½ ¨



 H ´ ú §s  s À Ò# Qt “ ¦ e ”  . Õ ª Q
 Ó ü t| 9 _  : £ ¤$ í † ¾ Ó © œ`  ¦ 0 A

∗

E-mail: [email protected]

K

 ì ø ͕ ¸^ ‰ r « Ñ\  ' ‘   ) a Cr, Fe 1 p x_  „  s  " é ¶ ™ è\  @ /ô  Ç

ƒ 

½ ¨  H ŠҖ Ð   † < Ê_  ¨ î \  | 9 ×  æ ÷ &# Q M ® o   [4]. : £ ¤ y  „   s

" é ¶ ™ è ×  æ Fe“ É r „   @ /– РÒ'  0.48 ∼ 0.52 eV_    ½ + Ë

\

 -t \  ¦ ° ú “ ¦ e ”   H Ga  o \  & h Ä » Ù ¼– Ð+ ‹, U  ·“ É r % 3 

!

s s'  ï  r0 A(deep acceptor level)\  ¦ + þ A$ í ô  Ç “ ¦ · ú ˜ 94 R e ” 



 [5–7].

‘

: r ƒ  ½ ¨\ " f  H Si s  “ ¦0 l x • ¸– Ð ' ‘   ) a n-GaAs_  r « Ñ

\

 Fe\  ¦ ³ ð€   š ¸% i r †   Ê ê, \ P  % ƒo \    É r : £ ¤$ í `  ¦ › ¸ 

% i  . \ P % ƒo   H “ : r • ¸ x 9  r ç ß –`  ¦    o\    É r PR: £ ¤$ í

`

 ¦ › ¸ , ì  r$ 3  % i  .

II. T  Â ] Ø

F 

g   › ¸ ì  rF  gZ O \ " f % 3 # Qt   H ’    ñ  H # Œ Q > h   • 2 ; + þ

AI – Ð Å Ò# Qt “ ¦ y Œ • ’    ñ_  e ” > & h “ É r 3  p ì  rZ O `  ¦  6   x

# Œ % 3 `  ¦ à º e ” Ü ¼ 9 Õ ª s  : rd ” “ É r  6 £ § õ  ° ú   .

∆R

R = Re[ X

Ce ^iϑ (E − E o + iΓ) ⁻ⁿ ] (1)

#

Œl " f R“ É r ì ø Í Ö  ¦ s “ ¦ Cü < ϑ  H y Œ •y Œ • ”  ; Ÿ ¤ õ  0 A © œ`  ¦
 

? /  H  כ Ü ¼– Ð,   › ¸’    ñ_  @ /g A$ í Ü ¼– РÒ'  ½ ¨½ + É Ã º e ”  Ü

¼ 9, E o ü < Í  H y Œ •y Œ • r « Ñ_  { ç ß –   \  -t ü < ¨ î ò ø ͓    s

“ ¦, n“ É r e ” > & h  " é ¶`  ¦
  · p .

-85-

Fig. 1. PR spectra obtained from n-GaAs n-GaAs sur- face treated with Fe.

“

¦ „  l  © œ  © œI \ " f  H PR’    ñ Airy† < Êà º\ " f p ì  r u

_  Y  L \  q Y Vô  Ç . s  כ `  ¦   H  r v €    6 £ § õ  ° ú    [8].

∆R R = cos

"

 2 3

  ~ω − E cp

~Ω



+ π(d − 1) 4

# (2)

#

Œl " f d  H e ” > & h _  " é ¶ s “ ¦, s  d ” _  ’    ñ + þ AI   H Franze Keldysh oscilation(FKO)_  ”  1 l x+ þ AI \  ¦ ”   .

s

 d ” \ " f ”  ; Ÿ ¤ כ ¹™ è\  ¦ Á ºr  €   FKO_  0 Au   H  6 £ § d ” 

\

 _ K    H    ) a   [9–11].

E j = ~Ω(F j ) + E g (3)

F j = [3π[(j − 1/2)/2]]

(4) 0

A_  d ” Ü ¼– РÒ'  F ^j \    É r E j _  Õ ªA á Ô\ " f l Ö  ¦ l   H

~ Ω s  9, ] X ¼ # “ É r  ½ ™× ¼Ì “ s \  -t s  .

III. ÷ m Ç] M ö U ê s0 n É

‘

: r ƒ  ½ ¨\ " f  6   xô  Ç r « э  H horizontal Bridgman(HB) Z O

\  _ K  $ í  © œ ) a n-GaAs : Si(n = 2.26 × 10 ¹⁸ cm ⁻³ ) s 



. „  s F K5 Å q š ¸% i \    É r n-GaAs ³ ð€   : £ ¤$ í `  ¦ › ¸  l  0 AK " f Fe– Ð š ¸% i r (   . # Œl " f Fe\  ¦ ³ ð€   š ¸% i r †   ~ ½ Ó Z O

“ É r €  $  r « Ñ\  ¦ % i í ß –\  { Œ ™½ ¨# Q 5ì  r& ñ • ¸ ™  ¥[ þ t€  " f [ j' ‘  ô 

Ç Ê ê, â ìØ Ô  H » 1 Ïs “ : r à º\  ¦ s 6   x # Œ 5ì  r& ñ • ¸ ' Ÿ ç  H  . Õ ª

Fig. 2. Relationship between F j and E j .

Ê

ê\  10 ppm & ñ • ¸_  Fe 6   xÓ  o`  ¦ [ j' ‘   ) a n-GaAs_  wafer

³

ð€  \  f  ¨‚ à Ìr (   . f  ¨‚ à ̝ ) a 6   xÓ  o`  ¦ r « Ñ ³ ð€   „  ^ ‰\  “ ¦ À

Ò ì  r Ÿ ír v l  0 AK " f spin dry\  ¦ % i Ü ¼ 9, s M : spin dry 5 Å q • ¸  H €  • 300 rpm & ñ • ¸s  .

PR 8 £ ¤& ñ “ É r   › ¸ F  g " é ¶ Ü ¼– РÒ'    © œs  6328 ˚ A ”   He-Ne laser\  ¦  6   x % i  . Probe c ” “ É r 250 W ½ + ɖ Ð
 p Ï þ

›á Ô\  ¦  6   x % i Ü ¼ 9 s \  ¦ œ í& h  o  0.27 m“   ì  r “ ¦€ Œ • l

(Spex 270M)\  E $ ™Ý ¼\  ¦ : Ÿ x # Œ | 9 5 Å q r v “ ¦, ì  rF  g l \  ¦ :

Ÿ

x K  é ß –Ò  o o  ) a y n C`  ¦ Si Ÿ íž Ð s š ¸× ¼– Ð  Ž Ø  ¦ # Œ s \  ¦ 7

£

x; Ÿ ¤ l \  ¦ : Ÿ x # Œ 7 £ x; Ÿ ¤ r †    6 £ §, lock-in 7 £ x; Ÿ ¤ l \  ¦  5 g ( Ž

É Ó' \  ½ ©   o  ) a   › ¸ ì ø Í Ö  ¦`  ¦ l 2 Ÿ ¤ % i  .

IV. ÷ m Ç] M ö + s ÇÊ Ý õ m Í À X Ø8 ý

Fig. 1“ É r 1 mW_    › ¸c ”  [ jl ü < 800 Hz_  Å Ò à º\  ¦ s

6   x # Œ n-GaAs\  Fe\  ¦ ³ ð€   š ¸% i r v l  „  õ  Ê ê_  r 

«

Ñ\  @ /ô  Ç 300 K\ " f 8 £ ¤& ñ ô  Ç PRÛ ¼& 7 ˜à Ô! 3 s  . Õ ªa Ë >\ 

"

f ˜ Ѝ  H  ü < ° ú  s  n-GaAs_  Å Òx ß ¼ Fe– Ð ³ ð€   š ¸% i 

`

 ¦ r (  `  ¦ M : 14.8 meV & ñ • ¸ $  \  -t  A á ¤ Ü ¼– Ð s 1 l x ÷ &% 3 

“

¦, ”  ; Ÿ ¤ s  €  • 80 % y Œ ™™ è÷ &% 3   H X <, Õ ª s Ä »– Ѝ  H Fe % ƒo 

\

 _ K " f r « Ñ ³ ð€  _    & ñ $ í s  $  ÷ &% 3 l  M :ë  H s  .

Fig. 2  H d ”  (2)\  ¦ s 6   x # Œ E ^j ü < F j \  ¦ ½ ¨ # Œ Õ ªA  á

Ô\  ¦ Õ ª 2 ;  כ s  . s  Õ ªA á Ô_  l Ö  ¦ l  [ O 1 l x: £ ¤$ í \  - t

(~Ω) ÷ & 9, ] X ¼ # s  E o  ÷ &  H X < s  ° ú כ`  ¦ ½ ¨ô  Ç   õ ,

Fig. 3. (a) PR spectra at 300 K from n-GaAs after furnace annealing at 200 ∼ 600 ^◦ C at furnace for 10 min. (b) PR spectra at 300 K from n-GaAs surface treated Fe after annealing 200 ∼ 600 ^◦ C for 10 min.

Fig. 4. (a) PR spectra from n-GaAs after furnace annealing for 10 ∼ 60 min at 300 ^◦ C. (b) PR spectra from n-GaAs surface treated with Fe after furnace annealing for 10 ∼ 60 min at 300 ^◦ C. (c) Relationship between annealing time electric filed and intensity.

n-GaAs \ " f_  E o ü < E o + ∆ o _  \  -t   H y Œ •y Œ • 1.431 eV ü

< 1.7771 eVs % 3 “ ¦, Fe\  ¦ ³ ð€   š ¸% i ô  Ç n-GaAs\ " f  H y Œ • y

Œ • 1.4371 eVü < 1.7763 eVs % 3  . s ü < ° ú  s  Fe\  ¦ ³ ð€  

š

¸% i ô  Ç n-GaAs E o  €  • 6 meV & ñ • ¸ ß ¼> 
 z Œ ¤  H X

<, s   H { 9  Òì  r s t ë ß – Feš ¸% i Ü ¼– Ð “  K  r « Ñ_  H o # Q

 ˜ Ð © œ÷ &% 3 l  M :ë  H s  .

Fig. 3(a), (b)  H y Œ •y Œ • n-GaAsü < Fe\  ¦ ³ ð€   š ¸% i ô  Ç n- GaAs\  ¦ “ : r • ¸Z > (200 ∼ 600 ^◦ C) – Ð 10 ì  rç ß – \ P % ƒo  ô  Ç Ê ê _  PR ’    ñs  . Õ ªa Ë >\ " f ˜ Ѝ  H  ü < ° ú  s  PR’    ñ_  ”  

;

Ÿ

¤ s  \ P % ƒo  “ : r • ¸ 300 ^◦ C  | ¨ c M : ”  ; Ÿ ¤ s  þ j@ / ÷ &  H X

<, s   H r « Ñ\  ' ‘   ) a Ô  ¦í  HÓ ü t[ þ t s  \ P % ƒo \  _ K " f ³ ð

€ 

 H o # Q 0 l x • ¸ 7 £ x  # Œ  ½ ™× ¼ … ô as  & t Ù ¼– Ð “  K " f

PR’    ñ_  ”  ; Ÿ ¤ s  þ j@ /  ) a  . Õ ªo “ ¦ s  \ P % ƒo  “ : r • ¸\ 

"

f ? / Ò\ " f ³ ð€  Ü ¼– Ð S X ‰í ß – ÷ &  H H o # Q & t l  M :ë  H s

  [12,13]. ì ø ̀  \  600 ^◦ C  | ¨ c M : t   H ”  ; Ÿ ¤ s  > 5 Å q y

Œ ™™ è   H X <, s   H ³ ð€   H o # Q_  y Œ ™™ è– Ð “  ô  Ç  ½ ™× ¼ … ô as 



Œ • t Ù ¼– Ð “  K " f PR’    ñ_  ”  ; Ÿ ¤ s  y Œ ™™ èô  Ç  [12–14].

Õ

ªo “ ¦ PR ’    ñ_  ”  ; Ÿ ¤_  y Œ ™™ è  H Fe % ƒo „  _  n- GaAs \  q K  €  • 17 % & ñ • ¸ 7 £ x  % i  . s   H Fe 

\ P

% ƒo  ´ òõ – Ð “  K  ? /Â Ò S X ‰í ß –(diffusion)\  _ K  Fe ⁺³  s

“ : r Ü ¼– Ð ÷ &# Q ×  æ$ í % 3 ! s s'   Œ •6   x`  ¦ l  M :ë  H s  .

Fig. 4(a), (b), (c)  H n-GaAs ü < Fe\  ¦ ³ ð€   š ¸% i  ô  Ç n- GaAs`  ¦ 300 ^◦ C \ " f \ P % ƒo  r ç ß –(10 ∼ 60 min)\     8

£

¤& ñ ô  Ç PR’    ñs  . Fig. 4(a)_  n-GaAs\ " f  H PR ’  

Fig. 5. Relationship surface and annealing times.

ñ ”  ; Ÿ ¤ s  \ P % ƒo  r ç ß –s  10 min\ " f 7 £ x    Õ ª s  Ê

ê– Ð y Œ ™™ èô  Ç . 7 £ ¤, \ P % ƒo  r ç ß –s  10 min\ " f_  PR ’    

ñ ”  ; Ÿ ¤_  7 £ x   H \ P % ƒo  ´ òõ \  _ K " f ³ ð€  \  Ass  Â Ò 7

á

¤ # Œ ³ ð€  \  + þ A$ í  ) a Ga oxide  & h  – Ð K o ÷ &# Q ³ ð€  

\

 Gas   r  7 £ x ÷ &l  M :ë  H s  9, Õ ª s Ê ê_  \ P % ƒo  r ç ß –

\

" f ”  ; Ÿ ¤_  y Œ ™™ è  H \ P % ƒo  ´ òõ \  _ K  ? / Ò\  ” > r F  

~ 

 Ass  ³ ð€  Ü ¼– Ð S X ‰í ß –÷ &“ ¦, s – Ð “  K " f ³ ð€  \ " f As_  Â

Ò7 á ¤ì  r`  ¦ ˜ Ð © œ Ù ¼– Ð “  K " f y Œ ™™ è  ) a   [15]. ì ø ̀  \  Fig.

4(b) \ " f ‘ : r  ü < ° ú  s  Fe\  ¦ ³ ð€   š ¸% i ô  Ç n-GaAs  H \ P % ƒ o

 r ç ß –s  7 £ x † < Ê\     PR ’    ñ ”  ; Ÿ ¤ s  > 5 Å q 7 £ x  

%

i   H X <, s   H \ P % ƒo  r ç ß –s  7 £ x † < Ê\    " f Fe r « Ñ

³

ð€    A – Ð { 9  Òì  r S X ‰í ß –÷ &€  " f, Ô  ¦í  HÓ ü t_   Ö ¸$ í  o– Ð “   K

 H o # Q_  7 £ x \  l “   ) a  .

Fig. 4(a) ü < 4(b)\ " f PR’    ñ_  [ jl \  ¦ \ P % ƒo  r ç ß –

\

   
 ? /€  , Fig. 4(c)ü < ° ú   .

Fig. 5 \ " f  H 300 ^◦ C \ " f \ P % ƒo  r ç ß –Z > \    É r n- GaAs ü < Fe\  ¦ ³ ð€   š ¸% i r †   n-GaAs_  ³ ð€   „  l  © œ_ 

 

 o\  ¦
 ? /% 3  . s  Õ ªA á Ô\  ¦ ¶ ú ˜( R˜ Ѐ  , n-GaAs_   â Ä

º\  \ P % ƒo  r ç ß –s  10 min{ 9  M :  H ³ ð€   „  l  © œs  7 £ x 

  Õ ª s Ê ê_  r ç ß –\   H y Œ ™™ èô  Ç . s   H \ P % ƒo  r ç ß – s

 10 min{ 9  M :  H H o # Q[ þ t_  7 £ x – Ð “  K " f „  l  © œs  7

£

x  “ ¦, Õ ª s Ê ê_  r ç ß –\  @ /K " f  H H o # Q[ þ t s  y Œ ™™ è

Ù ¼– Ð “  K " f „  l  © œ_  y Œ ™™ è   H X < s   H n-GaAs_  „   + þ

A& h “   \ P % ƒo  : £ ¤$ í s  . ì ø ̀  \  Fe\  ¦ ³ ð€   š ¸% i r †   n- GaAs  H „  l  © œs  > 5 Å q& h Ü ¼– Ð 7 £ x ô  Ç . s   H Fe  \ P % ƒ o

 ´ òõ \  _ K " f r « Ñ\  H o # Q 7 £ x ÷ &l  M :ë  H s  .

V. + s Ç Â ] Ø

n-GaAs ü < s  r « Ñ\  Fe\  ¦ ³ ð€   š ¸% i ô  Ç r †   Ê ê_  : £ ¤

$ í

`  ¦ › ¸  l  0 A # Œ s  ¿ ºr « Ñ\  ¦ > á ¤° ú  “ É r › ¸|  \ " f

“

: r • ¸, r ç ß –Z > – Ð \ P % ƒo \  ¦ ' Ÿ  l  „  õ  Ê ê_  : £ ¤$ í    o\  ¦ 8

£

¤& ñ , › ¸ ô  Ç   õ   6 £ § õ  ° ú  “ É r   õ \  ¦ % 3 % 3  .

n-GaAs ü < Fe\  ¦ ³ ð€   š ¸% i r †   n-GaAs\  ¦ 200 ∼ 600

◦ C  t  \ P % ƒo \  ¦ ô  Ç Ê ê, PR ’    ñ_  ”  ; Ÿ ¤ s  y Œ ™™ è   H q  Ö

 ¦ s    É r  , n-GaAs_   â Ä º  H 49 %“  X < q K  Fe\  ¦ ³ ð

€ 

 š ¸% i r †   n-GaAs  H 66 % – Ð €  • 17 %  8 ß ¼ . s   H Fe  ³ ð€   š ¸% i  ) a r « Ñ\ " f Fe \ P % ƒo  ´ òõ – Ð K  ? / Â

Җ Ð S X ‰í ß –(diffusion)H † d \  _ K " f Fe ⁺³  s “ : r Ü ¼– Ð ÷ &Ù ¼

–

Ð “  K " f ×  æ$ í % 3 ! s s'   Œ •6   x`  ¦ ô  Ç . s – Ð “  K  H o # Q

n-GaAs ˜ Ð   8 y Œ ™™ è >  ÷ &Ù ¼– Ð PR’    ñ_  ”  ; Ÿ ¤_  y Œ ™™ è

  H q Ö  ¦ s  & ”   . Fe\  ¦ ³ ð€   š ¸% i r †   n-GaAs\  ¦ 300

◦ C \ " f 10 ∼ 60 min \ P % ƒo \  ¦ % i `  ¦ M :, n-GaAs  H PR

’

   ñ ”  ; Ÿ ¤ õ  „  l  © œs  7 £ x    y Œ ™™ è   H n-GaAs_ 

„ 

+ þ A& h “   \ P % ƒo  ´ òõ 
 
  H X < q K  Fe\  ¦ ³ ð€   š ¸

%

i r †   n-GaAs  H > 5 Å q # Œ 7 £ x ô  Ç . s   H \ P % ƒo \  _  K

 Fe\  ¦ ³ ð€   š ¸% i r †   n-GaAs_  r « Ñ ³ ð€   : £ ¤$ í s  a % ~



t   H s Ä » M :ë  H Ü ¼– Ð Æ Ò& ñ  ) a  . ¢ ¸ô  Ç ¿ º r « Ñ\  @ /ô  Ç ³ ð

€ 

 „  l  © œ° ú כ`  ¦ ½ ¨ô  Ç   õ , n-GaAs  H 10 min \ " f 7 £ x  



 y Œ ™™ è   H „  + þ A& h “   : £ ¤$ í “  X < q K  Fe\  ¦ ³ ð€   š ¸% i  r

†   n-GaAs  H > 5 Å q 7 £ x  % i  . s   H ' ‘   ) a Fe  \ P 

%

ƒo – Ð “  K   Ö ¸$ í  o ÷ &# Q, r « Ñ\  H o # Q 7 £ x ÷ &% 3 l  M

:ë  H s  .

Y c

p w Š à U Ø ”  ô

[1] A. Badakhshan, J. Vac. Sci. Technol. 11, 169 (1993).

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A Photoreflectance Study of Iron-Contaminated n-GaAs

Jae-In Yu, K. H. Kim, D. Y. Lee and I. H. Bae ^∗

Department of Physics, College of Science, Yeungnam University, Gyeongsan 712-749 Young-Hee Mun

LG Siltron R&D Center, Gumi 730-350 (Received 20 May 2004)

We investigated the variation of the photoreflectance (PR) signals for n-GaAs surface treated with Fe and annealed. The samples were annealed by using the isochronal (200 ∼ 600

C, 10 min) and the isothermal(300

C, 10 ∼ 60 min) methods. The PR signals measured from the isochronally annealed samples showed intensity reductions of 49 % for n-GaAs and 66 % for Fe- treated n-GaAs We assume that the large decrease in intensity for the Fe- contaminated sample was caused by a decrease in the carrier density due to the increasing number of Fe

neutral acceptors at higher annealing temperature. The PR signals measured from isothermally annealed n-GaAs samples, decreased with increasing annealing time, and the signals for n-GaAs surface treated with Fe increased continuously with increasing annealing time. It can be assumed that the increasing PR intensity with annealing time for Fe-contaminated samples is due to a diffusion of Fe atoms from the surface.

PACS numbers: 73

Keywords: photoreflectance, Fe, GaAs

∗

E-mail: [email protected]