Effects of Heat Treatment in Air on Cu 2 ZnSnS 4 Thin Films Fabricated by Using Spray Pyrolysis Deposition

Effects of Heat Treatment in Air on Cu ₂ ZnSnS ₄ Thin Films Fabricated by Using Spray Pyrolysis Deposition

Chan Kim · Ilsu Rhee

Department of Physics, Kyungpook National University, Daegu 702-701, Korea

Sungwook Hong ^∗

Division of Science Education, Daegu University, Gyeongsan 712-714, Korea (Received 11 December 2014 : revised 27 January 2015 : accepted 5 February 2015)

Cu

2

ZnSnS

4

(CZTS) thin films were fabricated by using spray pyrolysis deposition. CZTS ink was prepared from CuCl

2

, ZnCl

2

, SnCl

2

, and thiourea (CH

4

N

2

S) powders that were dispersed in a mixed solution of 2-methoxyethanol and ethanolamine by using a sonochemical method. The films were fabricated by heat-treating the specimen in air and uniformly spraying CZTS ink on the glass. Heat treatment was performed at several different temperatures (300, 400, 500

^◦

C) and different durations (1, 2, 3 min). The best crystallinity and crystal size of the CZTS thin films were obtained at a temperature of 500

^◦

C for a 1-min treatment, according to X-ray diffraction measurement results. These results agree well with the data provided by the images of scanning electron microscopy. Furthermore, Hall-effect measurements on the sample confirmed that it was a p-type semiconductor and that its carrier concentration was 28.98 × 10

¹⁷

cm

⁻³

.

PACS numbers: 72.40.+w, 73.50.Pz

Keywords: CZTS, Spray pyrolysis, Heat treatment in Air, Thin film, Solar cell

­

Ž³ Ž7 _T  ° ‚ Ç Ä Z ØA 0 U ê s0 n É® Žz º < gX c l” X ¢ Cu 2 ZnSnS ₄ U c lT c l8 ý Œ Ÿ «M  ú n Þ ° ‚ Ç% iP  „ ÇÊ Ý



™ »¾ 6 Ò · T  G ž B¬ £

 â

· ¡ ¤ @ /† < Ɠ §  ƒ  õ † < Æ@ /† < Æ Ó ü t o † < Æõ , @ /½ ¨ 702-701

ý

— ¡) ç ] 8 ; ^∗

@

/½ ¨@ /† < Ɠ §  # 3 @ /† < Æ õ † < Ɠ §¹ ¢ ¤ † < Æ Ò,  â í ß – 712-714

(2014¸   12 Z 4 11{ 9  ~ à Î6 £ §, 2015¸   1 Z 4 27{ 9  à º& ñ ‘ : r ~ à Î6 £ §, 2015¸   2 Z 4 5{ 9  > F  S X ‰& ñ )

Cu

2

ZnSnS

4

(CZTS) ~ à Ì} Œ •`  ¦ Û ¼á ÔY Us  \ P ì  r K   ïh A~ ½ ÓZ O Ü ¼– Ð ] j Œ • % i  . Û ¼á ÔY Us   ïh A`  ¦ 0 A ô

 Ç CZTS 6   xÓ  o“ É r 2-methoxyethanol õ  ethanolamine_  ™ D ¥ ½ + Ë 6   xÓ  o\  % i  o½ ¨o  (CuCl

²

), % i  o ƒ   (ZnCl

2

), % i  oÅ Ò$ 3  (SnCl

2

), Thiourea (CH

4

N

2

S) ì  r ´ ú ˜`  ¦ V , “ É r Ê ê œ í6 £ §  – Ð ì  r í ß –r &  ] j› ¸ % i  .

s

 CZTS6   xÓ  o`  ¦ Ä »o  l ó ø Í\  “ ¦Ø Ô>  ì  r  ô  Ç Ê ê / B N l  ×  æ \ " f 300, 400, 500

^◦

C _  “ : r • ¸\ " f y Œ •y Œ • 1, 2, 3ì  r ç ß – \ P % ƒo  # Œ CZTS ~ à Ì} Œ •`  ¦ + þ A$ í % i  . X-‚    r] X  ì  r$ 3    õ  500

^◦

C _  “ : r • ¸\ " f 1ì  r ç ß – \ P % ƒ o

ô  Ç ~ à Ì} Œ •_    & ñ $ í õ    & ñ w n _  ß ¼l   © œ Ä ºÃ º % i Ü ¼ 9, s   H Å Ò ‰ & ³p  â Ü ¼– Ð S X ‰ “  ô  Ç   & ñ · ú ˜Ì q t s

_  ß ¼l    õ ü < ¸ ú ˜ { 9 u  % i  . ¢ ¸ô  Ç s  ~ à Ì} Œ •“ É r f . Ë ´ òõ  8 £ ¤& ñ Ü ¼– Ð 28.98 × 10

¹⁷

cm

⁻³

_  „    î  r ì ø Í



 0 l x • ¸\  ¦ t   H p-+ þ A ì ø ͕ ¸^ ‰e ” `  ¦ S X ‰ “   % i  .

129

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medium, provided the original work is properly cited.

I. " e  ] Ø

Cu 2 ZnSnS 4 (CZTS) ~ à Ì} Œ •“ É r “ ¦´ òÖ  ¦ _  Cu(In,Ga)Se ² (CIGS) ~ à Ì} Œ • I € ª œ„  t \   6   x ÷ &“ ¦ e ”   H “ ¦ " é ¶ ™ è“   “  

´

o u (In) õ  ° ú ˜µ ¢ § (Ga)`  ¦  ƒ   (Zn)õ  Å Ò$ 3  (Sn)Ü ¼– Ð @ /

^

‰ô  Ç ~ à Ì} Œ •s  . Znü < Sn“ É r t ½ ¨ © œ\  Õ ª B  © œ| ¾ Ós  Û  æ  Ò

l  M :ë  H \  ~ à Ì} Œ • I € ª œ„  t _  F  gf  ¨ à º8 £ x F « і Ð þ j   H \ 

´ ú

§“ É r Å Ò3 l q`  ¦ ~ à Γ ¦ e ”   [1–3]. CIGS l ì ø Í_  I € ª œ„  t 



 H \  -t    ¨ 8 Š ´ òÖ  ¦ s  20.8% t  • ¸² ú ˜ô  Ç ì ø ̀  \  CZTS l

ì ø Í I € ª œ„  t _  \  -t    ¨ 8 Š ´ òÖ  ¦“ É r Cu 2 ZnSn(S,Se) ₄ (CZTSSe)\  ¦ F  gf  ¨ à º8 £ x Ü ¼– Ð  6   x % i `  ¦ M : þ j@ / 12.6%  t


 è ß –  כ Ü ¼– Ð ˜ Г ¦÷ &% 3   [4, 5]. CZTS l ì ø Í_  I 

€

ª œ„  t   H CIGS l ì ø Í_  I € ª œ„  t ˜ Ð  ƒ  ½ ¨l ç ß –s   ú ªt  ë

ß – þ j@ / \  -t    ¨ 8 Š ´ òÖ  ¦ _  7 £ x  B Ä º  Ø Ô>  s À Ò# Q t

“ ¦ e ”  . : £ ¤ y , CZTS F  gf  ¨ à º8 £ x“ É r F  g † < Æ& h “   \  -t   ½ ™

×

¼Ì “ ss  1.5 eV– Ð I € ª œ„  t – Ð" f_  þ j& h \   î  r \  -t 



½ ™× ¼Ì “ s`  ¦ ”   f ” ] X  …  ;s + þ A ì ø ͕ ¸^ ‰s  9, F  gf  ¨ à º > à º

10 ⁴ cm ⁻¹ s  © œÜ ¼– Ð Z  } l  M :ë  H \  I € ª œ„  t _  F  gf  ¨ à º8 £ x Ü ¼

–

Ð+ ‹ Ø  æì  r ô  Ç : £ ¤$ í `  ¦ t “ ¦ e ”   [1,2]. ¢ ¸ô  Ç $ _  " é ¶

™

è\  ¦ F « і Ð s 6   x l  M :ë  H \  I € ª œ„  t  ] j› ¸ é ß –\  ¦ y Œ ™

™

èr ~  ´ à º e ”   H  © œ& h `  ¦ t “ ¦ e ”  .

Û

¼á ÔY Us  \ P ì  r K  ~ ½ ÓZ O `  ¦ s 6   x ô  Ç / B N& ñ “ É r “ ¦q 6   x _  ”   /

B

N  © œq \  ¦ s 6   x t  · ú §l  M :ë  H \  I € ª œ„  t _  ] j› ¸ é ß –

\

 ¦ ± ú Ø  ¦ à º e ”    H & h õ  / B G€   + þ AI _  l ó ø Í`  ¦ Ÿ í† < Êô  Ç — ¸

Ž

 H + þ AI _  l ó ø Í\  & h 6   x s  0 p x    H  © œ& h `  ¦ t “ ¦ e ” 



 [6–8].   " f  1 l x _  ü @Â Ò, | Ó ü t _  t Ô  æ x 9  ü @# 4 ,

– Ð1 p x _  „  1 p x y f ›õ  l Ñ ü æ 1 p x  € ª œô  Ç + þ AI \  ¦ ° ú   H ] j¾ ¡ § _  ü

@ Ò\  I € ª œ„  t \  ¦  ҂ à ̽ + É Ã º e ”   H / B N& ñ ~ ½ ÓZ O s  . Û ¼á Ô Y

Us  / B N& ñ \ " f  H I € ª œ„  t _  F  gf  ¨ à º8 £ x`  ¦ ½ ¨$ í   H Ó ü t| 9 

`

 ¦ €  $  6   xÓ  o  © œI – Ð ] j› ¸ô  Ç . Õ ª Ê ê s  6   xÓ  o`  ¦ Ä »o  l  ó

ø Í\  “ ¦Ø Ô>  ì  r   “ ¦ \ P % ƒo \  ¦ K " f F  gf  ¨ à º8 £ x Ó ü t| 9 `  ¦

 

& ñ  or †   .

‘

: r ƒ  ½ ¨\ " f  H % i ™ è o½ + ËÓ ü t“   CuCl 2 , ZnCl 2 , SnCl 2 ì  r

´ ú

˜õ  thiourea (CH 4 N ₂ S)\  ¦ s 6   x K  CZTS 6   xÓ  o`  ¦ ] j› ¸ 

“

¦, s  6   xÓ  o`  ¦ Ä »o l ó ø Í 0 A\  “ ¦Ø Ô>  ì  r  ô  Ç Ê ê \ P % ƒo 

\

 ¦ : Ÿ x # Œ CZTS ~ à Ì} Œ •`  ¦ ] j Œ • % i  . \ P % ƒo   H $ 3 % ò › ' a Ü

¼– Ð ] j Œ •  ) a > h~ ½ Ó+ þ A „  l – Ð î ß –\ " f ”  ' Ÿ  % i  . s X O >  /

B

N l  ×  æ \  ” ¸Ø  ¦ ) a > h~ ½ Ó+ þ A „  l – Ð ? /\ " f \ P % ƒo    H ~ ½ Ó d ”

“ É r ”  / B N  © œq \  ¦  6   x t  · ú §l  M :ë  H \  I € ª œ„  t  F  gf  ¨ Ã

º8 £ x ] j Œ • é ß –\  ¦ ? /w n = à º e ”  . Û ¼á ÔY Us  / B N& ñ õ  / B N l 

×

 æ \ " f \ P % ƒo ô  Ç CZTS ~ à Ì} Œ •s  I € ª œ„  t  F  gf  ¨ à º8 £ x Ü ¼– Ð

"

f_  : £ ¤$ í `  ¦ t “ ¦ e ” 6 £ §`  ¦ S X ‰ “   % i  .

∗

E-mail: [email protected]

II. ÷ m Ç ] M ö

Û

¼á ÔY Us  ì  r  \  ¦ 0 Aô  Ç Cu ₂ ZnSnS ₄ (CZTS) 6   xÓ  o`  ¦ ] j



Œ

• l  0 AK " f CuCl ² (Aldrich, 99%), ZnCl 2 (Sigma- Aldrich, ≥ 98%), SnCl ₂ (Sigma-Aldrich, 98%) ì  r ´ ú ˜ y Œ • y

Œ

• 2, 1, 1 mmol`  ¦ 2-methoxyethanol (Sigma-Aldrich, ≥ 99.8%) 3 ml ü < ethanolamine (Aldrich, ≥ 99.5%) 1ml_ 

™

D ¥ ½ + Ë 6   xÓ  o\  V , “ ¦ œ í6 £ §  – Ð 10ì  r ç ß – ì  r í ß –r &  Cu, Zn, Sn" é ¶ ™ è– Ð s À Ò# Q”   F K5 Å q „  ½ ¨^ ‰\  ¦ €  $  6   xÓ  o © œI – Ð ] j



Œ

• % i  . s  F K5 Å q „  ½ ¨^ ‰ 6   xÓ  o\  thiourea (CH ⁴ N 2 S, Sigma-Aldrich, ≥ 99%) ì  r ´ ú ˜ 4 mmol`  ¦ Æ Ò– Ð V , # Q œ í 6

£

§  – Ð 30ì  r 1 l x î ß – ì  r í ß –r & " f CZTS 6   xÓ  o`  ¦ ] j› ¸ % i  .

s

X O >  ] j› ¸  ) a CZTS 6   xÓ  o 0.1 ml\  ¦ 90 œ í 1 l x î ß – 170 ^◦ C – Ð

\ P  ) a 2.5 cm × 2.5 cm ß ¼l _  ™ è - e ”  (Soda-lime) Ä

»o  l ó ø Í 0 A\  Û ¼á ÔY Us  ~ ½ Ód ” Ü ¼– Ð “ ¦Ø Ô>  ì  r   % i  .



– Ð s # Q" f / B N l  ×  æ \ " f_  “ ¦“ : r \ P % ƒo \  ¦ : Ÿ x K  CZTS

~ Ã

Ì} Œ •`  ¦ ] j Œ • % i  . s  ~ à Ì} Œ •_  \ P % ƒo   H > h~ ½ Ó  ) a „  l – Ð î

ß –\ " f 300, 400, 500 ^◦ C _  “ : r • ¸\ " f y Œ •y Œ • 1, 2, 3ì  r 1 l x î

ß – s À Ò# Q& ’ “ ¦, \ P % ƒo \  ¦ ¢ - a « Ñô  Ç r « э  H  © œ“ : r \ " f  ƒ   Û

¼X O >  Í ‰ ty Œ •r (   .

CZTS ~ à Ì} Œ •_    & ñ $ í “ É r X-‚    r] X  (XRD, PANalyti- cal, Xïpert Pro.)`  ¦ : Ÿ x # Œ ì  r$ 3  % i “ ¦, ~ à Ì} Œ •_  ³ ð€  õ  é

ß –€  _  + þ A © œ“ É r „  > ~ ½ Ó + þ A Å Ò ‰ & ³p  â (FE-SEM, Hi- tachi, S-4800)`  ¦ s 6   x # Œ › ' a ¹ 1 Ï % i  . ¢ ¸ô  Ç ~ à Ì} Œ • ? /_  Cu, Zn, Sn, S _  $ í ì  r › ¸$ í q   H \  -t  ì  r í ß – X-‚   ì  rF  gZ O  (EDX, Horiba, X-Max.)`  ¦ s 6   x # Œ S X ‰ “   % i  . p-+ þ A ì ø Í

•

¸^ ‰_  : £ ¤$ í “ É r f . Ë ´ òõ  8 £ ¤& ñ  © œu  (Hall effect measure- ment system, Ecopia, HMS-3000)`  ¦ s 6   x # Œ S X ‰ “   % i 



.

III. + s ÇÊ Ý õ m Í À X Ø8 ý

\ P

% ƒo  “ : r • ¸ü < \ P % ƒo  r ç ß –\    É r CZTS ~ à Ì} Œ •_    & ñ

$ í

`  ¦ S X ‰ “   l  0 AK  X-‚    r] X  8 £ ¤& ñ `  ¦ % i Ü ¼ 9 Õ ª    õ

\  ¦ Fig. 1 \ 
 ? /% 3  . 300 ^◦ C " f 1ì  r ç ß – \ P % ƒo ô  Ç ~ Ã Ì }

Œ

•“ É r ü @ › ' a  © œ CZTS6   xÓ  os  ¢ - a„  y  ² D I t  · ú §€ Œ ¤t ë ß – CZTS

 

& ñ _  Å Ò x ß ¼“   (112)€  õ  (220)€  s 
 z Œ ¤ . 300 ^◦ C ü

< 400 ^◦ C \ " f \ P % ƒo ô  Ç ~ à Ì} Œ •“ É r \ P % ƒo  “ : r • ¸ü < \ P % ƒo  r

ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤ CZTS ~ à Ì} Œ •_    & ñ $ í s  a % ~  t   H  כ

`

 ¦ ^  ¦ à º e ”  . ì ø ̀  \  500 ^◦ C \ " f \ P % ƒo ô  Ç ~ à Ì} Œ •“ É r \ P 

%

ƒo  r ç ß –s  1ì  r{ 9  M :   & ñ $ í s   © œ Ä ºÃ º “ ¦, \ P % ƒo 

Fig. 1. (Color online) XRD patterns of CZTS films for various annealing conditions.

r

ç ß –s  2ì  r, 3ì  r Ü ¼– Ð 7 £ x ½ + Éà º2 Ÿ ¤   & ñ $ í “ É r š ¸y  9
 

&

’ Ü ¼ 9, ZnSü < Cu ² S 1 p x _  s    © œ_  x ß ¼
 z Œ ¤ .

Figure 2(a), (b), (c)  H \ P % ƒo  › ¸| _     o\    É r CZTS _

 (112)€  _  x ß ¼ — ¸€ ª œ    oü < x ß ¼ [ jl _     o\  ¦ ˜ Ð# Œ ï

 r  . Figure 2(b)  H y Œ •y Œ •_  \ P % ƒo  “ : r • ¸\ " f r ç ß –\   

 É

r x ß ¼ [ jl _     o\  ¦ ˜ Ð# Œï  r  . 300 ^◦ C ü < 400 ^◦ C \ " f

\ P

% ƒo ô  Ç ~ à Ì} Œ •“ É r \ P % ƒo  r ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤ (112)€   x  ß

¼_  [ jl  7 £ x  % i  . ì ø ̀  \  500 ^◦ C \ " f \ P % ƒo \  ¦ ô

 Ç ~ à Ì} Œ •_   â Ä º\   H \ P % ƒo  r ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤ š ¸y  9 (112)€   x ß ¼_  [ jl  y Œ ™™ è % i  . s   H \ P % ƒo  “ : r • ¸

500 ^◦ C p ë ß –“   ~ à Ì} Œ •\ " f  H \ P % ƒo  r ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤   

&

ñ $ í s  7 £ x  t ë ß –, \ P % ƒo  “ : r • ¸ 500 ^◦ C“   ~ à Ì} Œ •“ É r \ P 

%

ƒo  r ç ß –s  U  ´# Q| 9 à º2 Ÿ ¤ š ¸y  9 CZTS ~ à Ì} Œ •_    & ñ $ í s  y

Œ

™™ è† < Ê`  ¦
  · p . 300 ^◦ C ü < 400 ^◦ C \ P % ƒo  “ : r • ¸\ " f r

ç ß –\    É r x ß ¼ [ jl _  7 £ x   H |   \ P % ƒo  r ç ß –`  ¦ : Ÿ x

# Œ   & ñ $ í s  Ä ºÃ ºô  Ç CZTS ~ à Ì} Œ •`  ¦ % 3 `  ¦ à º e ” 6 £ §`  ¦
 

 · p . Õ ª Q
 ~ à Ì} Œ •_  „  ^ ‰  Òx \ " f   & ñ  o÷ &  H  Òì  r s

 t    H  Òx _  7 £ x Ö  ¦“ É r r ç ß –s  7 £ x † < Ê\     y Œ ™

™

è Ù ¼– Ð,  © œ@ /& h Ü ¼– Ð ± ú “ É r “ : r • ¸\ " f |   r ç ß –`  ¦ : Ÿ x # Œ

 

& ñ  o   H  כ “ É r í ß –\ O & h  Ò q tí ß –´ òÖ  ¦ 8 £ ¤€  \ " f q ´ òÖ  ¦& h “  

~

½ ÓZ O s   [9, 10]. Figure 2(c)  H 1 l x{ 9  \ P % ƒo  r ç ß –\  @ / K

" f “ : r • ¸ 7 £ x † < Ê\    É r   & ñ  o & ñ • ¸\  ¦ q “ §ô  Ç Õ ªA  á

Ôs  .  © œ@ /& h Ü ¼– Ð ± ú “ É r “ : r • ¸“   300 ^◦ C \ " f 400 ^◦ C ½ ¨ ç

ß –\ " f  H \ P % ƒo  r ç ß –s  U  ´# Q| 9 à º2 Ÿ ¤   & ñ  o÷ &  H & ñ • ¸



8 ß ¼   H  כ `  ¦ · ú ˜ à º e ”  . Õ ª Q
 400 ^◦ C \ " f 500 ^◦ C

–

Ð    o   H “ : r • ¸ ½ ¨ç ß –\ " f  H 1ì  r _   ú ª“ É r \ P % ƒo  r ç ß –\ 

•

¸   & ñ  o_  & ñ • ¸ B Ä º ß ¼>     o† < Ê`  ¦ ^  ¦ à º e ” “ ¦, \ P 

%

ƒo  r ç ß –s  U  ´# Qt €   š ¸y  9   & ñ  o÷ &  H & ñ • ¸  8  Œ •



t  
 y Œ ™™ è† < Ê`  ¦ ^  ¦ à º e ”  .   " f, ± ú “ É r “ : r • ¸\ " f

Fig. 2. (Color online) Changes in the (a) XRD main peak patterns, (b) main peak intensity versus time, (c) main peak intensity versus temperature, and (d) crys- talline size of CZTS films obtained at different annealing conditions.

| 

 r ç ß – 1 l x î ß – \ P % ƒo    H ~ ½ ÓZ O  ˜ Ð  Z  }“ É r “ : r • ¸\ " f  ú ª“ É r r

ç ß – 1 l x î ß – \ P % ƒo    H ~ ½ ÓZ O s  CZTS   & ñ `  ¦ + þ A$ í   H X <



8 & h ] X   . Z  }“ É r “ : r • ¸\ " f \ P % ƒo  r ç ß –`  ¦ U  ´>    H  כ s

 ~ à Ì} Œ •_    & ñ $ í `  ¦ y Œ ™™ èr v   H s Ä »  H 0 l q  H& h s  ± ú “ É r S !

 (S)s  / B N l  ×  æ Ü ¼– Ð 7 £ x µ 1 Ï÷ &# Q ~ à Ì} Œ •\ " f S ! s   Ò7 á ¤ K t  l

 M :ë  H s  . s   H Fig. 5 _  $ í ì  r › ¸$ í q  ì  r$ 3    õ ü < ¸ ú ˜ { 9

u ô  Ç . \ P % ƒo  r ç ß –`  ¦ 1ì  r ¢ ¸  H Õ ª s  – Ð “ ¦ “ : r • ¸

\

 ¦ 7 £ x    H › ¸| s  ~ à Ì} Œ •_    & ñ $ í `  ¦  8 a % ~ >  ½ + É # Œt   H e ”

Ü ¼
, l ó ø ÍÜ ¼– Ð s 6   x ÷ &  H ™ è - e ”  Ä »o _    + þ A “ : r • ¸

“

  573 ^◦ C ˜ Ð   8 Z  }“ É r “ : r • ¸  H & h 6   x s  Ô  ¦ 0 p x “ ¦ 1ì  r s

 _  r ç ß –“ É r r « Ñ “ ¦“ : r _  \ P % ƒo  „  l – Ð_  “ : r • ¸ü <

¨ î

+ þ As  ÷ &  H X < € 9 כ ¹ô  Ç r ç ß –`  ¦ “ ¦ 9Ù þ ¡`  ¦ M : / B N& ñ › ¸| Ü ¼

–

Ð & h ] X  t  3 l w % i  . Figure 2(d)  H \ P % ƒo  “ : r • ¸ü < \ P 

%

ƒo  r ç ß –\    É r CZTS ~ à Ì} Œ •_    & ñ w n  ß ¼l \  ¦
 ? /

%

3 Ü ¼ 9, Õ ª ß ¼l   H  A _  Scherrer / B Nd ” `  ¦ s 6   x # Œ >  í

ß – % i   [7].

D = 0.9λ

β cos θ

Annealing. 400

^◦

C 500

^◦

C

Conditions 1 min 2 min 3 min 1 min 2 min 3 min

Cu/(Zn+Sn) 0.54 0.83 0.83 0.98 1.06 1.00

Zn/Sn 2.03 1.33 1.20 1.38 1.21 1.02

S/(Metals) 0.70 0.75 0.75 0.71 0.58 0.51

Fig. 3. (Color online) Lattice constants of CZTS films for various annealing conditions.

#

Œl " f λ  H X‚  _    © œs  9 ⍠ H x ß ¼_  ì ø Íu ; Ÿ ¤ (Full width at half maximum, FWHM), Õ ªo “ ¦ θ  H Bragg y Œ •

•

¸s  . s  d ” `  ¦ s 6   x K  > í ß –ô  Ç CZTS ~ à Ì} Œ • ? /_    & ñ w n 

“

É r 500 ^◦ C p ë ß –\ " f \ P % ƒo ô  Ç ~ à Ì} Œ •\  @ /K " f  H \ P % ƒo  r

ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤ Õ ª ß ¼l  7 £ x  “ ¦, 500 ^◦ C \ " f \ P 

%

ƒo ô  Ç ~ à Ì} Œ •\ " f  H \ P % ƒo  r ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤ Õ ª ß ¼l 

 y Œ ™™ è % i  . 500 ^◦ C \ " f 1ì  r ç ß – \ P % ƒo ô  Ç ~ à Ì} Œ •_    & ñ w n

 ß ¼l   © œ ß ¼> 
 z Œ ¤Ü ¼ 9 s    õ   H X-‚    r] X 

 

õ \ " f
 è ß –   & ñ €  \  @ /ô  Ç x ß ¼ ß ¼l _     oü < 1 l x { 9

 > 
 z Œ ¤ . Figure 3“ É r \ P % ƒo  “ : r • ¸ü < \ P % ƒo  r  ç

ß –\    É r     © œÃ º_     o\  ¦
  · p Õ ªA á Ôs  . s    



  © œÃ º[ þ t“ É r Fig. 1 \ " f_  (112)€  õ  (220/204)€  \  @ /ô  Ç 2θ ° ú כ`  ¦ s 6   x # Œ   & ñ % i  . CZTS   & ñ “ É r ¹ ¢ ¤ ~ ½ Ó& ñ > 

Fig. 4. Cross section and surface SEM images of CZTS films for various annealing conditions: (a) 400 ^◦ C, 1 min;

(b) 400 ^◦ C, 2 min; (c) 400 ^◦ C, 3 min; (d) 500 ^◦ C, 1 min;

(e) 500 ^◦ C, 2 min; (f) 500 ^◦ C, 3 min.

(tetragonal) ½ ¨› ¸s Ù ¼– Ð,      © œÃ º  H  6 £ § d ” Ü ¼– Ð > í ß –

½

+ É Ã º e ”   [11].

4 sin ² θ

λ ² = h ² + k ² a ² + l ²

c ²

#

Œl " f h, k, l“ É r Miller €   t à ºs “ ¦, aü < c  H      © œÃ º s

 . Figure 3\ 
 è ß –  ü < ° ú  s  \ P % ƒo  › ¸| \    

 

   © œÃ º a  H €  • 0.02 ˚ A, c  H €  • 0.2 ˚ A # 3 0 A ? /\ " f   ô  Ç



. 500 ^◦ C \ " f 1ì  r ç ß – \ P % ƒo  ô  Ç CZTS ~ à Ì} Œ •_       © œ Ã

º  H a = 5.419 ˚ A, c = 10.844 ˚ A Ü ¼– Ð   & ñ ÷ &% 3  . s  ° ú כ

“

É r CZTS é ß –  & ñ _       © œÃ º ° ú כ“   a = 5.434 ˚ A õ  c = 10.856 õ  ¸ ú ˜ { 9 u ô  Ç  [12].

Figure 4  H CZTS ~ à Ì} Œ •_  é ß –€  õ  ¨ î €  _  SEM 8 £ ¤& ñ  

”

 `  ¦
  · p . \ P % ƒo  › ¸| s  400 ^◦ C _  1, 2, 3ì  r \  s 

#

Q" f 500 ^◦ C, 1ì  r Ü ¼– Ð    o | ¨ c à º2 Ÿ ¤ CZTS ~ à Ì} Œ •_  ¿ ºa ü <

~ Ã

Ì} Œ •`  ¦ s À ғ ¦ e ”   H { 9   · ú ˜Ì q ts  (grain)_  ß ¼l  7 £ x  H

†

d`  ¦ ^  ¦ à º e ”  . 500 ^◦ C \ " f \ P % ƒo ô  Ç ~ à Ì} Œ •_   â Ä º \ P % ƒ o

 r ç ß –s  2ì  r õ  3ì  r{ 9  M :  H CZTS ~ à Ì} Œ •_  ¿ ºa  \ P % ƒ o

 r ç ß –s  1ì  r“   ~ à Ì} Œ • ˜ Ð  · û ª & ’  . s   H 500 ^◦ C _  “ : r

•

¸\ " f 2ì  r s  © œ \ P % ƒo  ½ + É M :\   H CZTS\  ¦ s À ғ ¦ e ”   H

Table 2. Hall effect measurement results for CZTS films at various annealing conditions.

Annealing. 400

^◦

C 500

^◦

C

Conditions 1 min 2 min 3 min 1 min 2 min 3 min

N

Hall

[10

¹⁷

cm

⁻³

] 0.90 1.81 91.06 28.98 9.87 5.41

µ [cm

²

/Vs] 10.65 1.47 0.23 5.54 19.26 35.67

ρ [Ω cm] 6.50 23.59 2.92 0.39 0.33 0.32

Fig. 5. (Color online) Atomic composition ratios Cu/(Zn+Sn), Zn/Sn, and S/metals for the CZTS films obtained at different annealing conditions.

"

é

¶ ™ è[ þ t s  l ^ ‰_  + þ AI – Ð / B N l  ×  æ Ü ¼– Ð ± ú ˜ l  M :ë  H s 



. s   H EDX 8 £ ¤& ñ   õ \  ¦
 ? /  H Table 1 õ  Fig. 5\ 

"

f S X ‰ “   ½ + É Ã º e ”  . 500 ^◦ C \ " f 2, 3ì  r 1 l x î ß – \ P % ƒo ô  Ç ~ Ã Ì }

Œ

•\ " f  H F K5 Å q " é ¶ ™ è“   Cu, Zn, Sn \  q K  S_  | ¾ Ós  y Œ ™

™

èô  Ç  כ `  ¦ ^  ¦ à º e ”  . s   H “ ¦“ : r \ " f  © œ@ /& h Ü ¼– Ð |   r  ç

ß – 1 l x î ß – \ P % ƒo    H õ & ñ \ " f ~ à Ì} Œ • ? / Ò\  e ” ~   S / B N l

 ×  æ Ü ¼– Ð ± ú ˜ y Œ ¤l  M :ë  H s  . s – Ð “  K  Cu 2 ZnSnS 4 _ 



o† < Æ& h  { © œ| ¾ Óq  2:1:1:4\  ¦ Ø  æ7 á ¤ r v l \   H S _  € ª œs  ´ ú §s  Â

Ò7 á ¤  . Õ ª   õ  s [ þ t ~ à Ì} Œ •\ " f  H CZTS   & ñ $ í s  y Œ ™

™

è % i  . Õ ªo “ ¦ S_   Ò7 á ¤ Ü ¼– Ð CZTS_    & ñ $ í `  ¦ s À Ò t

 3 l w ô  Ç F K5 Å q[ þ t“ É r S ü < > hZ > & h Ü ¼– Ð  o† < Æ& h    ½ + Ë`  ¦ s À Ò

>

  ) a   [13]. Sns  Sü < Z  }“ É r “ : r • ¸\ " f  o† < Æ& h    ½ + Ë`  ¦ s  À

Ҁ   l ^ ‰  © œI “   SnS ë ß –[ þ t # Q4 R @ /l  ×  æ Ü ¼– Ð ± ú ˜ 

!

Qo  9, Cuü < Zn y Œ •y Œ • Sü <   ½ + Ë`  ¦ # Œ Cu ² S ü < ZnS

`

 ¦ + þ A$ í ô  Ç  [14]. s – Ð “  K  Fig. 1\ " fü < ° ú  s  500 ^◦ C

\

" f 2, 3ì  r ç ß – \ P % ƒo ô  Ç ~ à Ì} Œ •\ " f  H CZTS   & ñ $ í “ É r ×  ¦

#

QŽ  H ì ø ̀  \  Cu 2 S ü < ZnS_    & ñ s 
 
>   ) a  .

Table 2 \   H  © œ“ : r \ " f f . Ë ´ òõ  8 £ ¤& ñ  © œu – Ð 8 £ ¤& ñ ô  Ç CZTS ~ à Ì} Œ •_  f . Ë 0 l x • ¸ (Hall concentration, N Hall ), f . Ë Ä » 1

l x$ í (Hall mobility, µ), Õ ªo “ ¦ q $ † ½ Ó (Resistivity, ρ) ° ú כ

`

 ¦
 ? /% 3  . s  ° ú כ[ þ t“ É r t F K  t  ƒ  ½ ¨  ) a CZTS ~ à Ì} Œ • _

 f . Ë 0 l x • ¸, f . Ë Ä »1 l x$ í õ  q $ † ½ Ó ° ú כõ  q 5 p w   [15]. ¢ ¸ ô

 Ç CZTS ~ à Ì} Œ •_  f . Ë 0 l x • ¸ — ¸¿ º € ª œ_  ° ú כÜ ¼– Ð
 è ß –  כ

“ É

r ] j Œ •ô  Ç CZTS ~ à Ì} Œ •s  p-+ þ A ì ø ͕ ¸^ ‰e ” `  ¦ ´ ú ˜K ï  r  . s  ü

< ° ú  “ É r   õ   H Û ¼á ÔY Us  \ P ì  r K  ~ ½ ÓZ O Ü ¼– Ð ] j Œ • “ ¦ / B N l

 ×  æ \ " f \ P % ƒo ô  Ç CZTS~ à Ì} Œ •s  I € ª œ„  t _  F  gf  ¨ à º8 £ x Ü

¼– Ð  6   x ½ + É Ã º e ”   H Ø  æì  r ô  Ç 0 p x$ í s  e ” 6 £ §`  ¦ ´ ú ˜K ï  r  .

IV. + s Ç Â ] Ø

Û

¼á ÔY Us  \ P ì  r K  Z O Ü ¼– Ð ™ è  e ”  Ä »o  l ó ø Í\  Cu 2 ZnSnS 4 (CZTS) 6   xÓ  o`  ¦ “ ¦Ø Ô>  ì  r  ô  Ç Ê ê, / B N l  ×  æ

\

" f “ ¦“ : r Ü ¼– Ð \ P % ƒo    H ~ ½ ÓZ O Ü ¼– Ð CZTS ~ à Ì} Œ •`  ¦ + þ A$ í

% i  . 300, 400, 500 ^◦ C _  \ P % ƒo  “ : r • ¸\ " f y Œ •y Œ • 1, 2, 3ì  r _  \ P % ƒo  r ç ß –`  ¦    or v €  " f ] j Œ •ô  Ç CZTS ~ à Ì} Œ • _

 : £ ¤$ í `  ¦ › ¸  % i  . X-‚    r] X  ì  r$ 3    õ \   Ø Ô€   300, 400 ^◦ C \ " f \ P % ƒo ô  Ç ~ à Ì} Œ •\ " f  H \ P % ƒo  r ç ß –s  7

£

x ½ + Éà º2 Ÿ ¤   & ñ $ í s  7 £ x   ) a ì ø ̀  \  500 ^◦ C \ " f  H \ P 

%

ƒo ô  Ç ~ à Ì} Œ •“ É r \ P % ƒo  r ç ß –s  7 £ x ½ + Éà º2 Ÿ ¤   & ñ $ í s  y Œ ™

™

è÷ &% 3  . 500 ^◦ C \ " f 1ì  r ç ß – \ P % ƒo  ô  Ç ~ à Ì} Œ •s    & ñ $ í  © œ

€

 \ " f  © œ Ä ºÃ ºô  Ç : £ ¤$ í `  ¦ ˜ Ð% i  . s  ~ à Ì} Œ •_       © œ Ã

º  H a = 5.419 ˚ A, c = 10.844 ˚ A – Ð   & ñ ÷ &% 3 Ü ¼ 9 CZTS é

ß –  & ñ _       © œÃ ºü < ¸ ú ˜ { 9 u  % i  . 500 ^◦ C \ " f \ P % ƒ o

ô  Ç ~ à Ì} Œ •`  ¦ ] jü @ô  Ç ~ à Ì} Œ •[ þ t _   â Ä º \ P % ƒo  r ç ß –_  7 £ x 

\

      & ñ w n _  ß ¼l  — ¸¿ º 7 £ x ÷ &% 3  .   & ñ · ú ˜Ì q ts  _

 ß ¼l   H SEM 8 £ ¤& ñ `  ¦ : Ÿ x # Œ S X ‰ “   % i Ü ¼ 9, s   H XRD ì

 r$ 3 õ  1 l x{ 9 ô  Ç   õ \  ¦ ˜ Ð# ŒÅ Ò% 3  . EDX\  ¦ s 6   x K  ì  r$ 3  ô

 Ç CZTS ~ à Ì} Œ •_  $ í ì  r › ¸$ í q   H F K5 Å q" é ¶ ™ è_   â Ä º \ P % ƒo 

“

: r • ¸ü < r ç ß –s  7 £ x † < Ê\      o† < Æ& h  { © œ| ¾ Óq \   0 >

&

’ Ü ¼
, S  H 500 ^◦ C \ P % ƒo ô  Ç ~ à Ì} Œ •_   â Ä º \ P % ƒo  r ç ß – s

 7 £ x ½ + Éà º2 Ÿ ¤  Ò7 á ¤ >  ÷ &% 3  . s   H “ ¦“ : r \ " f \ P % ƒo  r

ç ß –s  U  ´# Qf ” \     S / B N l  ×  æ Ü ¼– Ð ± ú ˜ l  M :ë  H s

 . Hall 8 £ ¤& ñ `  ¦ : Ÿ x K   € ª œô  Ç \ P % ƒo  › ¸| Ü ¼– Ð ] j Œ •  ) a CZTS ~ à Ì} Œ •[ þ t s  — ¸¿ º p-+ þ A ì ø ͕ ¸^ ‰e ” `  ¦ S X ‰ “   % i  . s 

 

õ \  ¦ : Ÿ x K  Û ¼á ÔY Us  \ P ì  r K  ~ ½ ÓZ O Ü ¼– Ð ] j Œ •÷ &  H CZTS

~ Ã

Ì} Œ •_  / B N l  ×  æ þ j& h  \ P % ƒo  › ¸| “ É r 500 ^◦ C , 1ì  re ” `  ¦ · ú ˜ Ã

º e ” % 3 Ü ¼ 9, Û ¼á ÔY Us  / B N& ñ õ  / B N l  ×  æ \ " f_  \ P % ƒo  / B N

&

ñ `  ¦ & h 6   x   H $ _  CZTS F  gf  ¨ à º8 £ x ] j› ¸_  0 p x$ í `  ¦ S X

‰ “   % i  .

[1] H. Katagiri, K. Jimbo, W. S. Maw, K. Oishi and M.

Yamazaki et al., Thin Sold Films 517, 2455 (2009).

[2] D. B. Mitzi, O. Gunawan, T. K. Todorov, K. Wang and S. Guha, Sol. Energy Mater. Sol. Cells 95, 1421 (2011).

[3] W. Yang, H. S. Duan, B. Bob, H. Zhou and B. Lei et al., Adv. Mater. 24, 6323 (2012).

[4] P. Jackson, D. Hariskos, R. Wuerz, W. Wischmann and M. Powalla, Phys. Status Solidi (RRL) 8, 219 (2014).

[5] W. Wang, M. T. Winkler, O. Gunawan, T. Gokmen and T. K. Todorov et al., Adv. Energy Mater. 4, 1301465 (2014).

[6] Y. B. K. Kumar, G. S. Babu, P. U. Bhaskar and V. S. Raja, Sol. Energy Mater. Sol. Cells 93, 1230 (2009).

[7] V. G. Rajeshmon, C. S. Kartha, K. P. Vijayakumar, C. Sanjeeviraja and T. Abe et al., Solar Energy 85, 249 (2011).

[9] W. K. Kim, E. A. Payzant, S. Kim, S. A. Speakman and O. D. Crisalle et al., J. Cryst. Growth 310, 2987 (2008).

[10] K. A. Jackson, Kinetic Process (WILEY-VCH, 2004), Chap. 15.3.

[11] S. Chen, X. G. Gong, A. Walsh and S. Wei, Appl.

Phys. Lett. 94, 041903 (2009).

[12] P. Bonazzi, L. Bindi, G. P. Bernardini and S.

Menchetti, Can. Mineral. 41, 639 (2003).

[13] C. Kim and S. Hong, Mol. Cryst. Liq. Cryst. 586, 147 (2013).

[14] A. Redinger, D. M. Berg, P. J. Dale and S. Sieben- tritt, J. Am. Chem. Soc. 133, 3320 (2011).

[15] J. C. Gonzalez, P. A. Fernandes, G. M. Ribeiro,

A. Abelenda and E. R. Viana et al., Sol. Energy

Mater. Sol. Cells 123, 58 (2014).