AÅ Ò@ /† < Ɠ § „ & ñ ˜ Ð/ B N † < Æ Ò, ' õ AÅ Ò 360-746 (2007¸ 4 Z 4 18{ 9 ~ à Î6 £ §)

Si (111) M “ ˜ m ü; c AlN ! a( a• «ù p § T “ Ó Þ # b V R ËX ê s” X ¢ GaN U c lT c l • «8 ý ° Ë Ñ] K ¡X ì Äß Ã Å — ¤V R Ë



™ »%
¦  ^∗

' õ

AÅ Ò@ /† < Ɠ § „   & ñ ˜ Ð/ B N † < Æ Ò, ' õ AÅ Ò 360-746 (2007¸   4 Z 4 18{ 9  ~ à Î6 £ §)

Ä

»l  o† < Æl  © œ7 £ x ‚ Ã Ì  © œq \  ¦ s 6   x # Œ Si (111) l ó ø Í0 A\  GaN 8 £ x`  ¦ $ í  © œ r v “ ¦ AlN ! Q( 8 £ x ¿ º a

\    É r F  g † < Æ& h “   : £ ¤$ í `  ¦ ƒ  ½ ¨ % i  . AlN ! Q(  ¿ ºa  7 £ x † < Ê\     GaN 8 £ x _  donor bound exciton x ß ¼ 0 Au  ‚  + þ A& h Ü ¼– Ð red-shift % i Ü ¼ 9 ì ø Íu ; Ÿ ¤“ É r y Œ ™™ è % i  . Donor bound exciton x  ß

¼_  red-shift ‰ & ³ © œ“ É r d ” ô  Ç stress \  _ ô  Ç ç  H\ P \  _ ô  Ç  כ Ü ¼– Ð ó ø Íé ß –  ) a  . AlN ! Q(  80-nm ¿ ºa \ " f, photoluminescence 8 £ ¤& ñ   õ  13 K \ " f 17 meV _  ì ø Íu ; Ÿ ¤`  ¦ ° ú   H y © œô  Ç µ 1 Ï F  g x ß ¼\  ¦ % 3 % 3  . AlN

!

Q(  ¿ ºa \    É r GaN 8 £ x _  donor bound exciton  Ö ¸$ í  o \  -t \  ¦ ¨ î  % i  .

PACS numbers: 78.55.Cr, 78.66.Fd, 62.40+i

Keywords: Û ¼à ÔY UÛ ¼, ç  H\ P , z  ´o – B H (111), AlN ! Q( 8 £ x, Ä »l  o† < Æl  © œ7 £ x ‚ à Ì

I. " e  ] Ø

þ

j   H \ , Si l ó ø Í`  ¦ s 6   x ô  Ç GaN _  $ í  © œ ~ ½ ÓZ O s  ´ ú §“ É r Å

Ò3 l q`  ¦ ~ à Γ ¦ e ”  . Si l ó ø Í`  ¦ s 6   x † < ÊÜ ¼– Ð+ ‹ % 3 `  ¦ à º e ” 



 H  © œ& h “ É r $    o, @ /6   x | ¾ Ó o, Õ ªo “ ¦ a % ~“ É r \ P  x 9  „  l 

&

h

 „  • ¸$ í 1 p x s  e ”  . s  Qô  Ç ´ ú §“ É r  © œ& h \ • ¸ Ô  ¦ ½ ¨ “ ¦ Si l ó ø Ís  GaN $ í  © œ\   6   x ÷ &t  · ú §  H s Ä »  H GaN ~ à Ì} Œ • _

 ç  H\ P  (crack) Ò q t$ í M :ë  H s  . GaN ü < Si l ó ø Í s _ 

 H     © œÃ º Ô  ¦{ 9 u ü < \ P Ø Ÿ ‚ ½ Ó> à º_  s  e ” >  ¿ ºa 

œ

íõ ½ + É M : GaN_  ç  H\ P `  ¦ µ 1 ÏÒ q tr †   . ´ ú §“ É r ƒ  ½ ¨ [ þ t“ É r Si l ó ø Í\ " f ! Q(  (buffer) 8 £ x Ü ¼– Ð $ “ : r GaN \  ¦  6   x  l

 # Q§ > l  M :ë  H \  AlN [1], 3C-SiC [2], AlAs [3], Õ ªo “ ¦ HfN [4] _  ! Q( 8 £ x`  ¦  6   x # Œ “ ¦¾ ¡ §| 9 , Á ºç  H\ P  GaN \  ¦ % 3  l

 0 AK  ” ¸§ 4  “ ¦ e ”  . # Œ Q ! Q( 8 £ x[ þ t ×  æ \ " f ´ ú §“ É r ƒ  

½

¨ [ þ t“ É r Z  }“ É r “ : r • ¸\ " f î ß –& ñ ô  Ç AlN ! Q( 8 £ x`  ¦  6   x 

#

Œ “ ¦¾ ¡ §| 9 _  GaN ~ à Ì} Œ •`  ¦ % 3 % 3  . Watanabe [1]  H · û ª“ É r AlN é ß –  & ñ s  Si l ó ø Í 0 A\ " f GaN é ß –  & ñ `  ¦ $ í  © œ   H X

< ´ òõ & h “   ! Q( 8 £ xe ” `  ¦ ˜ Г ¦ % i  . Rehder [5]  H Si l  ó

ø Í 0 A\  Ä »l l  © œ7 £ x ‚ à ÌZ O  (MOVPE : metalorganic vapor phase epitaxy) Ü ¼– Ð $ í  © œô  Ç AlN _  Ó ü t o & h  ½ ¨› ¸ “ : r • ¸ ü

< V/III q \    y Œ ™† < Ê`  ¦ ˜ Г ¦ % i  . Si l ó ø Í 0 A\  AlN

!

Q( 8 £ x`  ¦ s 6   x ô  Ç GaN ~ à Ì} Œ •\  @ /ô  Ç ´ ú §“ É r ƒ  ½ ¨[ þ t s  $ í  © œ

~

½ ÓZ O  x 9  Ó ü t o & h  : £ ¤$ í \  @ /ô  Ç ƒ  ½ ¨– Ð ”  ' Ÿ ÷ &  H ì ø ̀   F  g † < Æ

&

h “   : £ ¤$ í \  @ /ô  Ç ƒ  ½ ¨  H ™ èà º\  Õ ªu “ ¦ e ”  .

∗

E-mail: [email protected]



 " f, ‘ : r ƒ  ½ ¨\ " f  H Ä »l  o† < Æl  © œ7 £ x ‚ à ÌZ O  (MOCVD : metalorganic chemical vapor deposi- ton) `  ¦ s 6   x # Œ AlN ! Q( 8 £ x ¿ ºa \    É r Si (111) l ó ø Í 0

A\  $ í  © œô  Ç GaN ~ à Ì} Œ •_  F  g † < Æ& h “   : £ ¤$ í `  ¦ ƒ  ½ ¨ % i  .

II. ÷ m Ç] M öU ê s0 n É

GaN ~ à Ì} Œ •“ É r MOCVD (Veeco  , D180GaN)  © œq \  ¦ s  6

 

x # Œ $ í  © œ ÷ &% 3  . GaN $ í  © œ`  ¦ 0 AK  (111) ~ ½ ӆ ¾ Ó Si (n+ þ A, 0.001Ω·cm) l ó ø Í`  ¦ s 6   x % i  . í ß – oÓ ü t s  \ O   H ³ ð

€

 `  ¦ 0 AK  à º™ è7 á x é ß – Si ³ ð€   % ƒo \  ¦ % i   [6]. AlN ü <

GaN 8 £ x“ É r TMGa, TMAl ü < NH

³

\  ¦ ™ èÛ ¼ Û ¼– Ð H

²

\  ¦ H

o # Q Û ¼– Ð  6   x # Œ 1070

^◦

C, 76 Torr ü < 1045

^◦

C, 200 Torr \ " f y Œ •y Œ • $ í  © œ % i  . AlN ! Q( 8 £ x`  ¦ $ í  © œ  l

 „  , Si (111) l ó ø ͓ É r H

2

ì  r 0 Al \ " f 1090

^◦

C – Ð \ P % ƒ o

 % i  . AlN ! Q( 8 £ x`  ¦ @ /| Ä Ì 35 nm, 65 nm, Õ ªo “ ¦ 80 nm – Ð $ í  © œô  Ç Ê ê 1045

^◦

C \ " f €  • 2.6 µm GaN ~ à Ì} Œ •`  ¦ $ í



© œ % i  .

AlN ¿ ºa \    É r GaN _  ç  H\ P x 9 • ¸  H Normalski ‰ & ³p 

 â

(x50) \  _ K  › ' a ¹ 1 Ï ÷ &% 3  . $ í  © œ  ) a GaN 8 £ x _    & ñ $ í

`

 ¦ › ' a ¹ 1 Ï l 0 AK  x-ray rocking curve (XRC) 8 £ ¤& ñ `  ¦ 

%

i “ ¦ F  g † < Æ& h “   : £ ¤$ í `  ¦ › ' a ¹ 1 Ï l 0 AK  13 K ∼ 300 K _ 

“

: r • ¸ # 3 0 A\ " f photoluminescence (PL) 8 £ ¤& ñ `  ¦ % i  .

-561-

Fig. 1 “ É r Normalski ‰ & ³p  â (x50) Ü ¼– Ð › ' a ¹ 1 Ï  ) a AlN

!

Q( 8 £ x ¿ ºa \     $ í  © œô  Ç GaN ~ à Ì} Œ •_  ³ ð€   ”  s  .

Fig. 1 (a) ∼ (c)  H AlN ! Q( 8 £ x ¿ ºa  35 nm, 65 nm, Õ ª o

“ ¦ 80 nm \ " f €  • 2.6 µm $ í  © œô  Ç GaN ~ à Ì} Œ •\  @ /ô  Ç ³ ð

€

 s  . — ¸Ž  H r « Ñ\ " f mirror-like ³ ð€  `  ¦ ˜ Ðs “ ¦ e ”  .

AlN ! Q( 8 £ x ¿ ºa  7 £ x † < Ê\    , GaN _  ç  H\ P x 9 • ¸  H è

 H \  ` (>  y Œ ™™ è % i  . 80-nm r « Ñ_   â Ä º,  _  Á ºç  H\ P 

\

  î  r ³ ð€  `  ¦ ˜ Ðs “ ¦ e ”  . s  ‰ & ³ © œ“ É r Si l ó ø Í0 A GaN ç

 H\ P   © œI  AlN ! Q( 8 £ x \   © œ{ © œy  % ò † ¾ Ó`  ¦ ~ à Î6 £ §`  ¦
 



· p . { 9 ì ø Í& h Ü ¼– Ð, Si l ó ø Í0 A GaN_  ç  H\ P “ É r tensile stress

\

 l “  K  µ 1 ÏÒ q t`  ¦ ô  Ç .   " f, s  Qô  Ç   õ   H AlN ! Q (

8 £ x ¿ ºa  7 £ x  €  " f GaN _  tensile stress  ¢ - a  o÷ &

%

3 l  M :ë  H“    כ Ü ¼– Ð ó ø Íé ß –  ) a  . 35 nm, 65 nm, Õ ªo “ ¦ 80 nm r « Ñ_  ç  H\ P x 9 • ¸  H y Œ •y Œ • 300 /cm, 40 /cm, Õ ªo “ ¦ 7 /cm s % 3  . 80nm AlN ! Q( 8 £ x`  ¦  6   x # Œ 1 µm $ í  © œô  Ç GaN ~ à Ì} Œ •\ " f Á ºç  H\ P ô  Ç ³ ð€  `  ¦ % 3 `  ¦ à º e ” % 3  .

AlN ! Q( 8 £ x ¿ ºa \    É r GaN 8 £ x _    & ñ $ í `  ¦ · ú ˜ ˜ Ð l

 0 AK  X-ray rocking curve (XRC) 8 £ ¤& ñ `  ¦ % i  . Fig.

2 \  (002) ì ø Íu ; Ÿ ¤ (FWHM : full width at half maximum) 8

£ ¤& ñ   õ 
 
 e ”  . AlN ! Q( 8 £ x ¿ ºa  7 £ x † < Ê\ 



 , GaN 8 £ x _    & ñ $ í s  7 £ x † < Ê`  ¦ ˜ Ðs “ ¦ e ”  . 35 nm, 65 nm, Õ ªo “ ¦ 80 nm AlN ¿ ºa \ " f_  (002) FWHM “ É r 680 arcsec, 544 arcsec, Õ ªo “ ¦ 437 arcsec – Ð y Œ ™™ è % i  .

¢

¸ô  Ç, XRC x ß ¼ y © œ• ¸\  ¦ ˜ Ѐ   AlN ! Q( 8 £ x ¿ ºa  7 £ x † < Ê

\

    (002) FWHM  â Ä º\   H 2.3 C  & ñ • ¸ x ß ¼ y © œ• ¸

† ¾

Ó © œ÷ &% 3  . 2.6 µm $ í  © œô  Ç GaN 8 £ x \ " f 437 arcsec _  (002) FWHM ° ú כ“ É r Si l ó ø Í\ " f $ í  © œô  Ç GaN 8 £ x _  ˜ Г ¦  ) a

 

õ  ×  æ \ " f  © œ{ © œy   Œ •“ É r ° ú כs  . s  ° ú כs  Si l ó ø Í\ " f “ ¦

¾

¡ §| 9  GaN 8 £ x s  $ í  © œ† < Ê`  ¦
 ? /t ë ß – ° ú  “ É r reactor \ " f



 s # Q l ó ø Í\ " f $ í  © œô  Ç GaN 8 £ x _  ° ú כ (∼300 arcsec)

\

 q K  # Œ„  y  Z  }  .

AlN ! Q( 8 £ x ¿ ºa \    É r   & ñ $ í † ¾ Ó © œs  F  g † < Æ& h “   : £ ¤$ í

\

 p u   H % ò † ¾ Ó`  ¦ › ' a ¹ 1 Ï l 0 AK  PL 8 £ ¤& ñ `  ¦ % i  . Fig.

3 “ É r  © œ“ : r \ " f 8 £ ¤& ñ  ) a AlN ! Q( 8 £ x ¿ ºa \    É r GaN 8 £ x _

 PL : £ ¤$ í `  ¦
 ? /“ ¦ e ”  . 35 nm, 65 nm, Õ ªo “ ¦ 80 nm AlN ¿ ºa \ " f_  PL x ß ¼ 0 Au   H 3.41 eV, 3.396 eV, Õ

ªo “ ¦ 3.396 eV % i Ü ¼ 9 AlN ! Q( 8 £ x ¿ ºa  7 £ x  €  

"

f x ß ¼ 0 Au  › ¸F Km ”  red-shift ÷ &% 3  . ¢ ¸ô  Ç, AlN ! Q(  8

£

x ¿ ºa  7 £ x  €  " f x ß ¼ y © œ• ¸  H & h & h  7 £ x  “ ¦ PL FWHM “ É r & h & h  y Œ ™™ è† < Ê`  ¦ ˜ Ðs “ ¦ e ”  . x ß ¼y © œ• ¸_   â Ä

º €  • 3.5 C  & ñ • ¸ † ¾ Ó © œ ÷ &% 3  . 35 nm, 65 nm, Õ ªo “ ¦ 80 nm AlN ¿ ºa \ " f_  PL FWHM “ É r y Œ •y Œ • 52.4 meV, 45 meV, Õ ªo “ ¦ 40.3 meV % i  .

Fig. 1. Photomicrographs of the 2.6-µm-thick GaN sur- face for AlN buffer thicknesses of (a) 35 nm, (b) 65 nm, and (c) 80 nm. The numbers of cracks for thicknesses of 35 nm, 65 nm, and 80 nm were 300/cm, 40/cm, and 7/cm, respectively.

Si l ó ø Í`  ¦ s 6   x # Œ $ í  © œô  Ç GaN 8 £ x _  red-shift ‰ & ³ © œ õ

 PL Û ¼& 7 ˜à Ô  (spectra) \  ¦ 7 á §  8  [ j >  ì  r$ 3  l  0 A K

 13 K “ : r • ¸\ " f 8 £ ¤& ñ % i “ ¦ Fig. 4 \ 
 
 e ”  . — ¸

Ž

 H GaN r « Ñ\ " f „  + þ A& h “   neutral donor bound exciton recombination (I

2

)  “  õ  ¿ º> h_  phonon replica 
 

z Œ ¤ . I

2

_  x ß ¼ 0 Au   H AlN ! Q( 8 £ x ¿ ºa  7 £ x \   



  © œ“ : r \ " fü < ° ú  s  ‚  + þ A& h Ü ¼– Ð red-shift ÷ &% 3  . 35 nm,

Fig. 2. (002) X-ray rocking curves of GaN layer with AlN buffer thickness.

Fig. 3. PL properties of GaN layer with AlN buffer thick- ness at RT.

65 nm, Õ ªo “ ¦ 80 nm AlN ¿ ºa \ " f_  I

²

x ß ¼0 Au   H y Œ • y

Œ

• 3.482 eV, 3.474 eV, Õ ªo “ ¦ 3.462 eV % i  . { 9 ì ø Í& h Ü ¼

–

Ð, I

²

x ß ¼  H Si l ó ø Í0 A GaN ~ à Ì} Œ •s  tensile stress \  ¦ ~ à Πl

 M :ë  H \  strain relaxation \  _ K  ' õ AÒ  o s 1 l x  ) a  . Õ ª



Q
 s    z  ´+ « >\ " f  H tensile stress  relaxation H † d \ • ¸ Ô

 ¦ ½ ¨ “ ¦ ì ø Í@ /_  ‰ & ³ © œs 
 z Œ ¤ . s    ‰ & ³ © œ“ É r  © œ{ © œô  Ç stress \  _ ô  Ç ~ à Ì} Œ •_  ç  H\ P  M :ë  H“    כ Ü ¼– Ð ó ø Íé ß –  ) a  . ü @ Â

Ò stress \    + þ A ) a GaN 8 £ x“ É r Õ ª ü @Â Ò stress  ] j  ÷ &

€

  " é ¶ A  t “ ¦ e ” ~   : £ ¤$ í Ü ¼– Ð { 9 & ñ  Òì  r ÷ &[  t  “ : r   [7].

7

£ ¤, ç  H\ P  ) a GaN ~ à Ì} Œ •“ É r stress  ¢ - a  o  ) a  © œI – Ð ÷ &“ ¦ Õ ª ç

 H\ P  ) a GaN 8 £ x _  I

²

x ß ¼  H strain relaxation  ) a GaN 8 £ x _

 I

²

x ß ¼\    H] X  >   ) a  .   " f,  © œ ´ ú §“ É r ç  H\ P `  ¦

˜

Г   35 nm AlN ! Q( 8 £ x r « Ñ_  I

²

x ß ¼  H stress  \ O   H GaN ~ à Ì} Œ •_  I

²

x ß ¼° ú כ\    H] X ô  Ç 3.48 eV \  ¦
 ? /% 3   [8]. ì ø Í@ /– Ð, 80 nm AlN ! Q( 8 £ x r « Ñ_  I

²

x ß ¼  H Si l  ó

ø Í 0 A\ " f ç  H\ P \ O s  $ í  © œô  Ç GaN ~ à Ì} Œ •_  I

²

x ß ¼° ú כ\    H ] X

ô  Ç 3.46 eV \  ¦
  · p  [9].  © œ“ : r \ " fü < ° ú  s  AlN ! Q (

8 £ x ¿ ºa  7 £ x  €  " f x ß ¼ y © œ• ¸  H & h & h  7 £ x  “ ¦ x 

Fig. 4. PL properties of GaN layer with AlN buffer thick- ness at 13K.

Fig. 5. Intensity variations of the I

2

as a function of the reciprocal temperature. Thermal activation energies of the I

₂

ranging from 25 to 27 meV were obtained from the slopes of the curves.

ß

¼_  FWHM “ É r & h & h  y Œ ™™ è† < Ê`  ¦ ˜ Ðs “ ¦ e ”  . x ß ¼ y © œ• ¸ _

  â Ä º €  • 6 C  & ñ • ¸ † ¾ Ó © œ ÷ &% 3  . 35 nm, 65 nm,Õ ªo “ ¦ 80 nm AlN ! Q( 8 £ x ¿ ºa \  @ /ô  Ç I

₂

x ß ¼_  FWHM “ É r y Œ • y

Œ

• 39 meV, 32 meV, Õ ªo “ ¦ 17 meV % i  .

Si l ó ø Í 0 A\  $ í  © œô  Ç GaN 8 £ x _  quantum efficiency _ 

“

: r • ¸ _ ” > r$ í `  ¦ ƒ  ½ ¨ l 0 AK  13 K ∼ 300 K “ : r • ¸ # 3 0 A\ 

"

f PL y © œ• ¸\  ¦ q “ § % i  . \ P & h Ü ¼– Ð Ä »• ¸  ) a / B N& ñ õ  ƒ  

› '

a$ í [ þ t`  ¦ S X ‰ z  ´y  l 0 AK  “ : r • ¸ † < Êà º– Ð — ¸Ž  H x ß ¼_  y © œ

•

¸    o\  ¦ ƒ  ½ ¨ % i  . “ : r • ¸ † < Êà º– Ð exciton transition õ 

› '

a >   ) a PL ~ ½ ÓØ  ¦ \  @ /ô  Ç { 9 ì ø Í o  ) a PL y © œ• ¸_  Arrhenius plot s  Fig. 5 \  ˜ Ð# Œ”   . Õ ªa Ë >`  ¦ ˜ Ѐ  , “ : r • ¸ 7 £ x 

€  " f µ 1 Ï F  g s  y © œ >  ™ èY >    H  כ `  ¦ · ú ˜ à º e ”  . 150 K s

 © œ_  “ : r • ¸\ " f PL y © œ• ¸ \ P & h Ü ¼– Ð  Ö ¸$ í  o H † d`  ¦ ˜ Г  



. “ : r • ¸ 150 K s  © œ\ " f ˜ Ðs   H f ” ‚  _  l Ö  ¦ l \ " f  Ö ¸

$ í

 o \  -t \  ¦ ½ ¨½ + É Ã º e ”  . 35 nm, 65 nm, Õ ªo “ ¦ 80

nm r « Ñ\ " f_  I

2

\  @ /ô  Ç  Ö ¸$ í  o \  -t   H y Œ •y Œ • 25.9

#

Œ $ í  © œô  Ç GaN 8 £ x \ " f 8 £ ¤& ñ ô  Ç  Ö ¸$ í  o \  -t ü < { 9 u  ô  Ç



.

IV. + s Ç Â ] Ø

‘

: r ƒ  ½ ¨\ " f  H MOCVD Z O Ü ¼– Ð AlN ! Q( 8 £ x › ¸] X `  ¦ :

Ÿ

x K  Si l ó ø Í0 A\  “ ¦¾ ¡ §| 9  GaN ~ à Ì} Œ •`  ¦ $ í  © œ % i  . é ß –t  AlN ! Q( 8 £ x ¿ ºa  › ¸] X ë ß –Ü ¼– Е ¸ Si (111) l ó ø Í 0 A\  7 £ x ‚ à Ì

 )

a GaN \ " f_  tensile stress \  ¦ ´ òõ & h Ü ¼– Ð y Œ ™™ èr ~  ´ à º e ”

“ ¦ ¢ ¸ô  Ç   & ñ | 9 `  ¦ † ¾ Ó © œ r ~  ´ à º e ”  . s      õ   H AlN

!

Q( 8 £ x s  Si (111) l ó ø Í 0 A\ " f GaN $ í  © œ\  ×  æ כ ¹ô  Ç % i ½ + É

`

 ¦ † < Ê`  ¦
  · p . AlN ! Q( 8 £ x ¿ ºa  80-nm { 9 M : þ j& h  _

 GaN : £ ¤$ í `  ¦ ˜ Ð% i Ü ¼ 9 80-nm AlN ! Q( 8 £ x`  ¦ s 6   x # Œ

€



• 1 µm ¿ ºa \ " f Á ºç  H\ P  GaN ~ à Ì} Œ •`  ¦ $ í  © œ % i  .

Y

c p w Š à U Ø ”  ô

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McGill and T. F. Kuech, Mater. Res. Soc. Symp.

Proc. 395, 243 (1996).

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Weber, S. Shinkai and K. Sasaki, Appl. Phys. Lett.

81, 1450 (2002).

[5] E. Rehder, M. Zhou, L. Zhang, N. R. Perkins, S. E.

Babcock and T. F. Kuech, MRS Internet J. Nitride Semicond. Res. 4S1, G3.56 (1999).

[6] G. S. Higashi, Y. J. Chabal, G. W. Trucks and K.

Laghavachari, Appl. Phys. Lett. 56, 656 (1990).

[7] C. Kisielowski, J. Kr¨ uger, S. Ruvimov, T. Suski, J.

W. Ager, E. Jones, Z. Liliental- Weber, M. Rubin, E. R. Weber, M. D. Bremser and R. F. Davis, Phys.

Rev. B 54, 17745 (1996).

[8] B. Monemar, Phys. Rev. B 10, 676 (1974).

[9] A. Strittmatter, A. Krost, M. Strassburg, V. T¨ urk and D. Bimberg, Appl. Phys. Lett. 74, 1242 (1999).

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J. Appl. Phys. 79, 2784 (1996).

The Optical Properties of a GaN Layer on Si (111) With an AlN Buffer

Deok Kyu Kim

^∗

Division of Electronics and Information Engineering, Cheongju University, Cheongju 360-746 (Received 18 April 2007)

GaN layers were grown on silicon (111) substrates with AlN buffer layers by using metalorganic vapor phase epitaxy, and the varitations in the optical properties of the GaN layer with the AlN buffer layer

⁰

s thickness were investigated. As the AlN thickness increased, the peak position of the donor-bound exciton of the GaN layer was red-shifted linearly, and the full width at half maximum (FWHM) of the donor-bound exciton peak decreased. The red-shift of the donor-bound exciton peak was attributed to cracks due to heavy stress. In 80-nm-thick AlN, a strong band-edge emission of the GaN layer on Si (111) was observed, with the full width at half maximum of the bound-exciton line being as low as 17 mev at 13 K. The activation energy of the donor-bound exciton was evaluated for GaN layers for various AlN thicknesses.

PACS numbers: 78.55.Cr, 78.66.Fd, 62.40+

Keywords: Stress, Crack, Silicon (111), AlN buffer, Metalorganic chemical vapor deposition

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