Determination of the Optical Properties of AlGaAs/GaAs Multiple Quantum Wells by Using Power-dependent Photoluminescence

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Determination of the Optical Properties of AlGaAs/GaAs Multiple Quantum Wells by Using Power-dependent Photoluminescence

Janghyun Cho · Yong-Sub Jung · Clare Chisu Byeon ^∗

School of Mechanical Engineering, Kyungpook National University, Daegu 702-701, Korea

Jin Dong Song · Eun Hye Lee

Center for Opto-Electronic Convergence Systems, Korea Institute of Science & Technology, Seoul 136-791, Korea

(Received 13 December 2013 : revised 19 January 2014 : accepted 12 February 2014)

We fabricated AlGaAs/GaAs multiple quantum wells by using molecular beam epitaxy (MBE).

We deposited a GaAs buffer layer on a n-type GaAs wafer and stacked AlGaAs and GaAs layer by layer 20 times. The optical properties of the AlGaAs/GaAs multiple quantum wells were analyzed by using photoluminescence (PL) spectroscopy. By increasing the excitation power from 20 mW to 140 mW, we observed 2 PL peaks, on each at 803 nm and 812 nm; the PL intensity increased linearly with increasing power, and the peak wavelengths shifted to longer wavelengths by about 5 nm. We expect that the observed red shifts originate from the AC Stark effect by which the local energy band structure changes momentarily in response to the optical excitation field. The results show the possibility of bandgap engineering by external excitation, providing key information on the functionality of AlGaAs/GaAs multiple quantum wells for developing device applications.

PACS numbers: 78.55.Cr, 78.66.Fd, 81.15.Hi

Keywords: Photoluminescence, AlGaAs/GaAs quantum well, Red shift

#

bM ° Ë ÑÌ ¦ R8 ý û s ÚI í Ä ì Å× D; c Â \ ¥ AlGaAs/GaAs W ë s ¤ö n Ú º8 ý Photoluminescence ° Ë Ñ ¤V R Ë Ä Z ØV Ä

Ð ç ¡g ` @ · + ä ÷ 7 B) כ · _ @U ¬ £ ^∗

â

· ¡ ¤ @ / < Æ § l > / B N < ÆÂ Ò, @ /½ ¨ 702-701

ö

¶

B . > ò 6 B · T ª <A j

F

g Ö 6 x ½ + Ër Û ¼% 7 ½ ¨é ß ,ô Ç² D G õ < Æl Õ ü t ½ ¨" é ¶, " fÖ ¦ 136-791

(2013¸ 12 Z 4 13{ 9 ~ Ã Î6 £ §, 2014¸ 1 Z 4 19{ 9 Ã º& ñ : r ~ Ã Î6 £ §, 2014¸ 2 Z 4 12{ 9 > F S X & ñ )

MBE ~ ½ ÓZ O Ü ¼ Ð $ í © r AlGaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸\ " f # l F g _ Ø ¦§ 4 o\ É r F g µ 1 Ï F

g (photoluminescence, PL) : £ ¤$ í ` ¦ ì r$ 3 % i . n-type GaAs l ó ø Í0 A\ GaAs! Q( 8 £ x` ¦ + þ A$ í r Ê ê AlGaAs/GaAs\ ¦ ° ú 9 $ í © r r « Ñ\ # l F g _ Ø ¦§ 4 ` ¦ 20 mW \ " f 140 mW t or v

9 8 £ ¤& ñ % i . 803 nm, 812 nm\ " f 2> h_ PL 4 x Ä ºo © s ' a8 £ ¤ ÷ &% 3 Ü ¼ 9, # l F g _ Ø ¦§ 4 s 7 £ x

< Ê\ PL [ jl + þ A& h Ü ¼ Ð 7 £ x % i ¦, PL 4 x Ä ºo © s 5 nm & ñ ¸ & h Ò o¼ # s z ¤ .

&

h

Ò o¼ # s & ³ © _ Å Ò" é ¶ É r # l F g [ jl _ o\ É r AC Stark ´ òõ \ _ ô Ç \ -t ½ × ¼½ ¨ ¸_ 121

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.

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PACS numbers: 78.55.Cr, 78.66.Fd, 81.15.Hi

Keywords: F g µ 1 Ï F g , AlGaAs/GaAs × æ ª Ä ºÓ ü t, & h Ò o¼ # s

I. " e Â ] Ø

III-V7 á ¤ " é ¶ è_ ½ + Ë GaAs H Si l ì ø Í_ ì ø Í ¸^ ü < q

§ # Z } É r s 1 l x ¸, V , É r ½ × ¼Ì s, Z } É r Å Ò Ã º % ò

%

i \ " f_ & h É r ¸s Ý ¼, f ] X ½ × ¼Ì s 1 p x _ © & h ` ¦ ° ú ¦ e

# Q LED [1], 0 A$ í : x [2], Y Us $ [3], ¦ s 1 l x ¸ à

Ô ½ t Û ¼' (HEMT) [4] 1 p x ª ô Ç 6 £ x6 xì r \ " f ½ ¨

' ÷ &# Q M ® o . s Qô Ç ½ ¨ H ] j / B N& ñ _ µ 1 Ï õ 8Ô ¦

#

Q $ í © % i H X <, è+ þ A o, ¦| 9 & h o, ¦´ òÖ ¦$ í ` ¦ Æ Ò½ ¨ 9 8 ¦ ! 9î r Ó ü t| 9 ] j l Õ ü t x 9 èF > hµ 1 Ïs '

÷

& ¦ e . : £ ¤ y , ] j Ó ü t _ ß ¼l ¸é ß 0 A Ð t ,

ª ½ ¨5 Å q ´ òõ > ÷ & H X < s Ð # ¸ : £ ¤

$ í

s F g < Æ : £ ¤$ í 1 p x s l > r _ Z O ß ¼ Ó ü t| 9 [ þ t õ H B Ä º Ø

Ô> è ß . ª & h [5], ª Ä ºÓ ü t [6], ¸ü <s # Q [7]

1 p

x þ j H Y > ¸ ç ß ª ½ ¨5 Å q ´ òõ \ ¦ 6 £ x6 x 9 H ½ ¨ '

÷ &# Q M ® o [8]. ª Ä ºÓ ü t ½ ¨ ¸\ ¦ ° ú H Y Us $ [9], I ª

t [10]ü < ° ú s 2 " é ¶ ª ½ ¨5 Å q ´ òõ \ ¦ ° ú H Ó ü t| 9 É r Õ ª

¿

ºa ¸] X s " é ¶ 8 £ x é ß 0 A Ð ¸] X 0 p x ½ + É & ñ ¸_ ] j l Õ

ü

t s µ 1 Ï² ú % i .

:

£

¤ y , ì r $ í © ~ ½ ÓZ O (molecular beam epitaxy, MBE) É r í ¦ / B N, q \ P ¨ î + þ A © I \ " f 7 £ x Ã Ì÷ & H ~ ½ Ód Ü ¼

Ð, Ô ¦í HÓ ü t _ D ¥{ 9 s & h ¦ $ : r \ " f $ í © s 0 p x 9, H

& h \ " f ç H{ 9 ô Ç \ x 8 £ x + þ A$ í s 0 p x ¦ ¸$ í s Ô ¦ í

HÓ ü t 0 l x ¸_ ] j# Q ç H{ 9 H © & h s e # Q ª Ä ºÓ ü t

½

¨ ¸\ ¦ ° ú H è ] j \ V , o s 6 x ÷ & ¦ e [11].

AlGaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸ H 1.42 eV (873 nm) _ ½ × ¼Ì s \ -t \ ¦ ° ú H GaAs ü < 1.92 eV (645 nm) _ ½ × ¼Ì s \ -t \ ¦ ° ú H AlGaAs § $ í © ÷ &# Q s

À Ò# Q4 R" f, GaAs ( J $ [ > Ä ºÓ ü t` ¦ + þ A$ í ¦ AlGaAs

(

J $ [ > © # 4 ` ¦ + þ A$ í H ½ ¨ ¸ Ð s À Ò# Q4 R e [12,13].

Al _ ¸$ í q Ö ¦ s Z } | 9 Ã º2 ¤ © Ã º_ o H _

\ O

Ü ¼ ½ × ¼Ì s É r 7 £ x H X < s \ ¦ ½ ÓÜ ¼ Ð & ñ ~ ½ Ó ¾ Ó

$ í

© s 0 p x ½ + É M : H& h ü @ @ /% i _ Y Us $ s ¸× ¼\ ¦ ë ß [

þ

t Ã º e [9]. s % ! 3 AlGaAs/GaAs ª Ä ºÓ ü t ½ ¨ ¸\ ¦

° ú

H Y Us $ s ¸× ¼ H 6 £ x6 x é ß > \ e Ü ¼ 9, è Ð ] j

r z ´] j ½ ¨1 l x \ " f_ $ í 0 p x s \ V8 £ ¤ 0 p x ô Ç ½ ¨ '

÷

&# Q ô Ç .

∗

E-mail: [email protected]

Fig. 1. (Color online) AlGaAs/GaAs multiple quan- tumwell structure.

: r 7 Hë H \ " f H MBE ~ ½ Ód ` ¦ : x K $ í © r Al- GaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸\ " f # l F g " é ¶ _ Ø ¦§ 4 [ j l

\ É r F g µ 1 Ï F g : £ ¤$ í ` ¦ ' a8 £ ¤ < ÊÜ ¼ Ð+ ü @Â Ò # l \ _ ô

Ç ² D G Â Ò& h \ -t ½ ¨ ¸ o\ ¦ ½ ¨ # , s Qô Ç ½ ¨ ¸

\

¦ 6 £ x6 x ô Ç è _ > hµ 1 Ï x 9 Ö ¸6 x` ¦ 0 Aô Ç l í & ñ Ð\ ¦ ] j /

B

N ¦ ô Ç .

II. ÷ m Ç ] M ö

1. GaAs quantum well S Å

z

´+ « >\ 6 x ô Ç Al _0.4 Ga 0.6 As/GaAs × æ ª Ä ºÓ ü t r « Ñ

H ì ø Í] X GaAsl ó ø Í © \ MBE $ í © ~ ½ ÓZ O Ü ¼ Ð $ í © ÷ &% 3

. MBE H Riber _ Compact21` ¦ 6 x % i Ü ¼ 9, Å Òì ø Í 6

£ xz ´ (main chamber)_ / B N É r ion getter pump x 9 cryo- genic pump Ð C l # $ í © \ 1.0 × 10 ⁻⁹ Torr s _

· ú § 4 , $ í © × æ \ 1.0 × 10 ⁻⁷ Torr _ í ¦ / B N · ú § 4 ` ¦

. r ¼ # _ ] j É r 6 £ § õ ° ú s ' ÷ &% 3 . ì ø Í] X

GaAs l ó ø Í` ¦ ¸{ 9 z ´ (load lock chamber) Ð V , ¦ 1.0

× 10 ⁻⁶ Torr _ / B N Ü ¼ Ð C l ô Ç Ê ê 100 ^◦ C \ " f

\ P ` ¦ z ´r % i . s Ê ê ï r q z ´ (preparation cham- ber) \ " f © l l ó ø Í` ¦ 400 ^◦ C s © \ P # ï r q z ´ /

B

N s 1.0 × 10 ⁻⁹ Torr s Ð ? / 9y ¤` ¦ M : l ó ø Í © _ ¸% i Ó

ü t| 9 s Ø æì r y Û ¼~ ½ ÓØ ¦ ÷ & ¸2 ¤ ô Ç Ê ê, Å Òì ø Í6 £ xz ´ Ð ì ø Í] X

GaAs` ¦ î r ì ø Í ¦, 620 ^◦ C \ " f As4\ ¦ ¸{ 9 # l ó ø Í

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Fig. 2. (Color online) PL spectra of AlGaAs/GaAs mul- tiple quantum wells depending on excitation power.

³

ð _ í ß oÓ ü t s Ø æì r y ] j ÷ & ¸2 ¤ % i . s M : l ó ø Í

³

ð _ í ß o} ] j H RHEED (Reflection high-energy electron diffraction) Û ¼ß ¼ 2 ; © \ " f " î Ñ þ ô Ç × ¦ Á º] ( + þ A J

s ` ¦ M : t ' ô Ç Ê ê l ó ø Í_ : r ¸\ ¦ 580 ^◦ C

Ð ? /o ¦ GaAs! Q( 8 £ x` ¦ 0.1 µm$ í © % i . $ í © Ê ê RHEED J © Ü ¼ Ð " î Ñ þ ô Ç 2 × 4J ` ¦ ^ ¦ Ã º e % 3 .

$ í

© ô Ç ½ ¨ ¸ H 6 £ § õ ° ú . l ó ø Í : r ¸\ ¦ 620 ^◦ C t

`

¦ 2 ; Ê ê © l ! Q( 8 £ x 0 A\ 10 nm ¿ ºa _ Al 0.4 Ga _0.6 As` ¦

$ í

© ¦, Õ ª 0 A\ 4.5 nm¿ ºa _ GaAsü < 5 nm¿ ºa _ Al 0.4 Ga 0.6 As\ ¦ 20 ì ø Í4 ¤ # $ í © % i . $ í © \ 6 x ô

Ç Ga x 9 Al/ B N/ å L" é ¶ É r VEECO \ " f / B N/ å L ô Ç SUMO K- cell s 9, As4/ B N/ å L" é ¶ É r Riber \ " f ] j/ B N ô Ç 6 \ Ú Ô © Ã Ì \ P ì

r W+ þ A As cell (VAC 500)s . GaAs x 9 AlGaAs_ $ í © Ò

¦ É r y y 0.141 nm/s, 0.094 nm/ss .

2. PL ¤X N Ë

· ú

¡" f ï r q ô Ç ª Ä ºÓ ü t ½ ¨ ¸ AlGaAs/GaAs r ¼ # _ \

-t ½ ¨ ¸ ì r$ 3 ` ¦ 0 A # F g µ 1 Ï F g (PL) \ _ ô Ç F g: £ ¤

$ í

ì r$ 3 ` ¦ ' % i . F g µ 1 Ï F g z ´+ « > É r SPECTRO _ Mmac200 (f = 200 mm) ì rF g l ü < PM100U photomul- tiplier tube (PMT)\ ¦ s 6 x # ½ ¨$ í % i ¦, F g " é ¶ Ü ¼ Ð H

s ¸× ¼ Y Us $ (λ = 532 nm)\ ¦ 6 x # z ´+ « > % i .

III. + s ÇÊ Ý õ m Í w ² o

8 £ ¤& ñ ) a PL spectrum \ " f H ¿ º > h_ 4 x Ä ºo H 803 nm Â Ò H \ " f, É r H 812 nm Â Ò H \ " f z

`

¦ · ú Ã º e % 3 . × æ ª Ä ºÓ ü t ½ ¨ ¸ Ô ¦í HÓ ü t s ½ ¨ ¸

Fig. 3. (Color online) Peak fitting of PL spectra of Al- GaAs/GaAs multiple quantum wells by Gaussian.

&

h + þ As \ O s ¢ - a# 4 > $ í © ÷ &% 3 B Ä º ; ¤ s a % v

É

r é ß { 9 4 x Ä ºo ' a8 £ ¤ ÷ &# Q t ë ß , 8 £ ¤& ñ ) a r « Ñ\ " f

H ¿ º > h_ 4 x Ä ºo ' a8 £ ¤ ÷ &% 3 . III-V7 á ¤ ì ø Í ¸^ × æ Ä

ºÓ ü t ½ ¨ ¸\ " f H / B N: x& h & ³ © _ 0 p x$ í ` ¦ ¦ 9

# [14,15], × æ 4 x Ä ºo µ 1 ÏÒ q t H " é ¶ Ü ¼ Ð H ] j õ

& ñ \ " f µ 1 ÏÒ q t½ + É Ã º e H < Ê (defect)õ Ô ¦í HÓ ü t _ 0 l x ¸ (impurity), # l © I s [15]1 p x _ 0 p x$ í Ü ¼ Ð Ò q ty K

^

¦ Ã º e Ü ¼ , z ´ : r \ " f s À Ò# Q z ´+ « >e ` ¦ ¦ 9½ + ÉM : $ í

© ¸| _ \ Vl u · ú § É r è_ Ô ¦ î ß & ñ $ í \ _ ô Ç y 8 £ x _

¿

ºa o\ É r \ -t ½ ¨ ¸_ s Ð Æ Ò8 £ ¤ ) a .

#

l F g " é ¶ _ Ø ¦§ 4 ° ú כ` ¦ 20 mW \ " f 140 mW t 20 mW ç ß Ü ¼ Ð 8 £ ¤& ñ ô Ç õ \ ¦ Fig. 2 \ ? /% 3 . # l F

g " é ¶ _ Ø ¦§ 4 ° ú כ 7 £ x H PL _ Intensity_ 7 £ x ü < PL peak _

& h Ò o¼ # s & ³ © ` ¦ l r ( .

4 x Ä ºo 0 Au \ É r \ -t ½ ¨ ¸ o_ ì r$ 3 ` ¦ 0 A

#

Fig. 2\ " f è ß PL spectra\ ¦ 2 > h_ Gaussian 4 x Ä

ºo Ð ì r K # H % i . (Fig. 3) × æd © s 803 nm (peak 1)` ¦ ° ú H PL spectrum õ × æd © s 812 nm (peak 2)\ ¦ ° ú H PL spectrum É r # l F g _ [ jl 7 £ x ½ + É M

: ¸¿ º © © A á ¤ Ü ¼ Ð s 1 l x H & h Ò o¼ # s (red-shift) â

¾ Ós è ß .

Figure 4 \ " f H ì r K ) a ¿ º 4 x Ä ºo # l F g _ [ jl

7 £

x < Ê\ © © A á ¤ Ü ¼ Ð y y s 1 l x < Ê` ¦ Ð# ï r .

¿

º 4 x Ä ºo ¸¿ º × æd © s # l F gØ ¦§ 4 ° ú כ_ 7 £ x \

+ þ A 7 £ x \ ¦ ¦ e Ü ¼ 9, _ ° ú É r l Ö ¦ l Ð 7 £ x

< Ê` ¦ · ú Ã º e % 3 . # l F g " é ¶ _ Ø ¦§ 4 \ -t 20 mW

\

" f (peak 1)_ © s 803 nm\ ¦, (peak 2) _ © É r 812 nm\ ¦ ? /% 3 Ü ¼ 9, 140 mW\ " f H (peak 1) s 808 nm\ ¦, (peak 2) s 817 nm\ ¦ ? /% 3 . s Qô Ç õ

H y y _ 4 x Ä ºo \ K { © H \ -t ½ × ¼Ì ss + þ A& h Ü ¼

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Fig. 4. (Color online) PL peak wavelength shifts of Al- GaAs/GaAs multiple quantum wells depending on the excitation power.

Fig. 5. (Color online) PL peak intensity changes of Al- GaAs/GaAs multiple quantum wells depending on exci- tation power.

Ð y è ¦ e 6 £ §` ¦ ? / 9, ª ½ ¨5 Å q (Quantum Con- finement) Stark ´ òõ (QCSE) [17, 18]ü < \ P & h ´ òõ _ 0

p x$ í [16]Ü ¼ Ð ^ ¦ Ã º e .

Figure 5 \ " f H # l F g _ Ø ¦§ 4 ° ú כ\ É r 4 x Ä ºo [ jl _

7 £ x \ ¦ · p . # l F g " é ¶ _ Ø ¦§ 4 \ -t ° ú כs 7 £ x

½

+ ÉÃ º2 ¤ ¿ º µ 1 Ï F g _ [ jl H ¸¿ º + þ A& h Ü ¼ Ð 7 £ x % i Ü ¼

É r l Ö ¦ l \ ¦ t 9 7 £ x % i . 4 x Ä ºo [ jl _ + þ

A& h 7 £ x H 140 mW _ # l F g Ø ¦§ 4 ° ú כ % ò % i t H #

_ q + þ A & ³ © s { 9 # Q ¦ e t · ú §6 £ §` ¦ ? / 9, s

½

¨ ¸\ " f µ 1 Ï F g ´ òÖ ¦ s { 9 & ñ > Ä »t ÷ & ¦ e 6 £ §` ¦ · p

.

Figure 6 \ " f H Fig .3 \ " f ì r K ) a y y _ µ 1 Ï F g ½ × ¼\ ¦

&

h

ì r ô Ç ° ú כ` ¦ ? /% 3 . PL spectrum \ " f [ jl _ & h ì r

° ú

כ É r z ´| 9 & h Ü ¼ Ð µ 1 Ï F g ÷ & H F g _ Ã º\ ¦ f ] X & h Ü ¼ Ð

? / H t ³ ð Ð 6 x ) a . # l F g " é ¶ _ Ø ¦§ 4 \ -t ° ú כs

Fig. 6. (Color online) Integrated PL intensity changes of AlGaAs/GaAs multiple quantum wells depending on excitation power.

Fig. 7. (Color online) FWHM (Full width at half max)of PL peaksof AlGaAs/GaAs multiple quantum wells de- pending on excitation power.

7 £

x ½ + ÉÃ º2 ¤ ¿ º ½ × ¼ ¸¿ º + þ A& h Ü ¼ Ð [ jl & h ì r ° ú כs 7 £ x

% i Ü ¼ É r l Ö ¦ l \ ¦ t 9 7 £ x % i . 4 x Ä ºo [

jl ü < PL [ jl _ & h ì r ° ú כs # l F g _ [ jl \ É r l

Ö ¦ l Ð 7 £ x ¦ e 6 £ § É r : £ ¤& ñ © (peak intensity)s

½ × ¼ (integrated intensity)\ Ã Ð# H F g _ Ã º

© @ /& h Ü ¼ Ð è ² ú t ¦ e 6 £ §` ¦ Ð# Å Ò 9, s H ¿ º ½

×

¼\ K { © H s S X Ò ¦ s # l F g _ Ø ¦§ 4 ° ú כ\ ©

@

/& h Ü ¼ Ð o ¦ e 6 £ §` ¦ · p .

#

l F g " é ¶ _ \ -t 7 £ x < Ê\ 4 x Ä ºo [ jl H peak 2 _ 7 £ x Ö ¦ s peak 1_ 7 £ x Ö ¦ Ð 2C / å L y 7 £ x

% i Ü ¼ (Fig. 5), ½ × ¼ ; ¤ É r band 1 s band 2 Ð

8 Ø Ô> 7 £ x % i . s H # l F g _ [ jl 7 £ x

"

8 À 1 Ïo Z þ t # Q ¦ e Ü ¼ , ^ µ 1 Ï F g ½ × ¼\ Ã Ð# H F g

(5)

Ã º H band 1 s 8¹ ¡ ¤ À 1 Ïo Z þ t # Q ¦ e 6 £ §` ¦ Ð# ï r .

s

&

h ' aº s e .

#

l F g _ [ jl \ É r y y _ 4 x Ä ºo _ ì ø Íu ; ¤ (FWHM)` ¦ 8 £ ¤& ñ ô Ç õ (Fig. 7), ¿ º Õ ªA á Ô ¸¿ º p [ j

> 7 £ x % i Ü ¼ 9, 7 £ x Ö ¦ É r peak 1 s peak 2 Ð 2C

&

ñ ¸ ß ¼> 8 £ ¤& ñ ÷ &% 3 . s Qô Ç õ H 4 x Ä ºo _ [ jl _ 7

£

x Ö ¦ s ± ú t ë ß ½ × ¼_ ; ¤ s Ø Ô> 7 £ x # ' Í P :

½ × ¼_ V , s ¿ º P : ½ × ¼\ q K 8 Ø Ô> 7 £ x < Ê` ¦ z

´

» ~ Ã Îg Ë > H õ Ð ^ ¦ Ã º e .

#

l F g [ jl _ 7 £ x \ É r FWHM _ ° ú כ_ 7 £ x H \ P

&

h ´ òõ \ É r & h Ò o¼ # s _ 0 p x$ í ¸ ] jr % i .

IV. + s Ç Â ] Ø

ü

t ½ ¨ ¸\ ¦ ° ú H r « Ñ\ " f # l F g " é ¶ _ Ø ¦§ 4 o\ É r F

g µ 1 Ï F g (PL): £ ¤$ í ` ¦ ' a8 £ ¤ % i . r « Ñ_ ½ ¨ ¸& h Ô ¦ î ß & ñ

$ í

Ü ¼ Ð # ¿ º > h_ PL 4 x Ä ºo > r F 9, # l F g

"

é

½

9, s H ü @Â Ò_ # l \ ² D G Â Ò& h \ -t ½ ¨ ¸ p [

j > o # & h ¢ ¸ H F g < Æ& h : £ ¤$ í \ % ò ¾ Ó

`

¦ Å Ò> H d` ¦ · ú Ã º e .

× æ ª Ä ºÓ ü t ½ ¨ ¸\ ¦ ° ú H AlGaAs/GaAs r « Ñ\ " f # l

F g [ jl \ É r \ -t ½ × ¼½ ¨ ¸ o\ ' a ô Ç ½ ¨ H 6

£

x6 x è _ > hµ 1 Ï x 9 Ö ¸6 x \ e # Q" f z ´] j ½ ¨1 l x r è _

B

N ½ + É כ Ü ¼ Ð l @ /÷ & 9, p [ jô Ç \ -t ½ ¨ ¸ o\ É r

Ð [ jô Ç : £ ¤$ í o ì r$ 3 ` ¦ 0 A # $ : r z ´+ « >, r ì r K PL, p è% ò % i _ PL8 £ ¤& ñ s Æ Ò& h Ü ¼ Ð ' | ¨ c > S \ s

.

P

c p 8 ý ò k >

s

7 Hë H É r 2010¸ ¸ §¹ ¢ ¤ õ < Æl Õ ü t Â Ò_ F " é ¶ Ü ¼ Ð ô Ç² D G

½ ¨F é ß _ t " é ¶` ¦ ~ Ã Î Ã º' ) a l í ½ ¨ \ O e (NRF- 2010-0012862). s 7 Hë H É r 2012 < Æ¸ ¸ â · ¡ ¤ @ / < Æ § < ÆÕ ü t

½ ¨q \ _ # ½ ¨÷ &% 3 6 £ §.

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Determination of the Optical Properties of AlGaAs/GaAs Multiple Quantum Wells by Using Power-dependent Photoluminescence

Determination of the Optical Properties of AlGaAs/GaAs Multiple Quantum Wells by Using Power-dependent Photoluminescence

Janghyun Cho · Yong-Sub Jung · Clare Chisu Byeon ∗

School of Mechanical Engineering, Kyungpook National University, Daegu 702-701, Korea

Jin Dong Song · Eun Hye Lee

Center for Opto-Electronic Convergence Systems, Korea Institute of Science & Technology, Seoul 136-791, Korea

(Received 13 December 2013 : revised 19 January 2014 : accepted 12 February 2014)

We fabricated AlGaAs/GaAs multiple quantum wells by using molecular beam epitaxy (MBE).

PACS numbers: 78.55.Cr, 78.66.Fd, 81.15.Hi

Keywords: Photoluminescence, AlGaAs/GaAs quantum well, Red shift

#

bM ° Ë ÑÌ ¦ R8 ý û s ÚI í Ä ì Å× D; c  Â \ ¥ AlGaAs/GaAs W ë s  ¤ö n Ú  º8 ý Photoluminescence ° Ë Ñ ¤V R Ë Ä Z ØV Ä



Ð ç ¡g ` @ · + ä  ÷ 7 B) כ · _  @U ¬ £ ∗

 â

· ¡ ¤ @ / < Æ § l > / B N  < ÆÂ Ò, @ /½ ¨ 702-701

ö

¶

B . > ò 6 B · T ª <A j

F

g  Ö 6 x ½ + Ër Û ¼% 7   ½ ¨é ß ,ô  Ç² D G õ  < Æl Õ ü t  ½ ¨" é ¶, " fÖ  ¦ 136-791

(2013¸  12 Z 4 13{ 9  ~ Ã Î6 £ §, 2014¸  1 Z 4 19{ 9  Ã º& ñ  : r ~ Ã Î6 £ §, 2014¸  2 Z 4 12{ 9  > F  S X & ñ )

MBE ~ ½ ÓZ O Ü ¼ Ð $ í  © r   AlGaAs/GaAs ×  æ  ª  Ä ºÓ ü t ½ ¨ ¸\ " f # l  F g _  Ø  ¦§ 4   o\    É r F g µ 1 Ï F

g (photoluminescence, PL) : £ ¤$ í `  ¦ ì  r$ 3 % i  . n-type GaAs l ó ø Í0 A\  GaAs! Q( 8 £ x`  ¦ + þ A$ í r   Ê ê AlGaAs/GaAs\  ¦   ° ú    9 $ í  © r   r « Ñ\  # l  F g _  Ø  ¦§ 4 `  ¦ 20 mW \ " f 140 mW t    or  v

 9 8 £ ¤& ñ % i  . 803 nm, 812 nm\ " f 2> h_  PL 4  x Ä ºo   © s   ' a8 £ ¤ ÷ &% 3 Ü ¼ 9, # l  F g _  Ø  ¦§ 4 s  7 £ x

 < Ê\     PL [ jl    + þ A& h Ü ¼ Ð 7 £ x  % i  ¦, PL 4  x Ä ºo   © s  5 nm & ñ  ¸ & h Ò  o¼ # s   z  ¤ .

&

h

Ò  o¼ # s  & ³ © _  Å Ò" é ¶    É r # l  F g [ jl _    o\    É r AC Stark ´ òõ \  _ ô  Ç \  -t   ½ × ¼½ ¨ ¸_    121

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PACS numbers: 78.55.Cr, 78.66.Fd, 81.15.Hi

Keywords: F g µ 1 Ï F g , AlGaAs/GaAs ×  æ  ª  Ä ºÓ ü t, & h Ò  o¼ # s 

I. " e Â ] Ø

III-V7 á ¤ " é ¶  è_    ½ + Ë  GaAs  H Si l ì ø Í_  ì ø Í ¸^ ü < q 



§ #  Z  } É r     s 1 l x  ¸, V ,  É r  ½ × ¼Ì  s, Z  } É r Å Ò Ã º % ò

%

i \ " f_  & h  É r  ¸s Ý ¼, f  ] X   ½ × ¼Ì  s 1 p x _   © & h `  ¦ ° ú  ¦ e 

# Q LED [1], 0 A$ í :  x  [2], Y Us $  [3],  ¦    s 1 l x  ¸ à

Ô ½ t Û ¼' (HEMT) [4] 1 p x  ª ô  Ç 6 £ x6 xì  r  \ " f   ½ ¨



 '  ÷ &# Q M ® o . s  Qô  Ç   ½ ¨  H ] j   / B N& ñ _  µ 1 Ï  õ   8Ô  ¦

#

Q $ í  ©  % i   H X <,  è+ þ A o,  ¦| 9 & h o,  ¦´ òÖ  ¦$ í `  ¦ Æ Ò½ ¨  9  8    ¦ ! 9î  r Ó ü t| 9 ] j  l Õ ü t x 9    èF  > hµ 1 Ïs    '  

÷

& ¦ e   . : £ ¤ y , ] j  Ó ü t _  ß ¼l   ¸é ß 0 A Ð    t   ,



ª  ½ ¨5 Å q ´ òõ    >  ÷ &  H X < s  Ð   #     ¸ : £ ¤

$ í

s   F g  < Æ : £ ¤$ í 1 p x s  l  > r _  Z O ß ¼ Ó ü t| 9 [ þ t õ   H B Ä º  Ø

Ô>   è ß  .  ª  & h  [5],  ª  Ä ºÓ ü t [6],  ¸ü <s # Q [7]

1 p

x þ j   H Y > ¸  ç ß   ª  ½ ¨5 Å q ´ òõ \  ¦ 6 £ x6 x  9  H   ½ ¨   '

 ÷ &# Q M ® o  [8].  ª  Ä ºÓ ü t ½ ¨ ¸\  ¦ ° ú   H Y Us $  [9], I  ª 



 t  [10]ü < ° ú s  2 " é ¶  ª  ½ ¨5 Å q ´ òõ \  ¦ ° ú   H Ó ü t| 9  É r Õ ª

¿

ºa   ¸] X s  " é ¶  8 £ x é ß 0 A Ð  ¸] X  0 p x ½ + É & ñ  ¸_  ] j   l  Õ

ü

t s  µ 1 Ï² ú  % i  .

:

£

¤ y , ì  r    $ í  © ~ ½ ÓZ O  (molecular beam epitaxy, MBE) É r  í ¦  / B N, q \ P ¨ î + þ A  © I \ " f 7 £ x  Ã Ì÷ &  H ~ ½ Ód  Ü ¼



Ð, Ô  ¦í  HÓ ü t _   D ¥{ 9 s  & h  ¦ $  : r \ " f $ í  © s  0 p x  9,  H



 & h \ " f ç  H{ 9 ô  Ç \ x 8 £ x + þ A$ í s  0 p x  ¦  ¸$ í s   Ô  ¦ í

 HÓ ü t 0 l x  ¸_  ] j# Q ç  H{ 9     H  © & h s  e  # Q  ª  Ä ºÓ ü t

½

¨ ¸\  ¦ ° ú   H  è  ] j  \  V , o  s 6 x ÷ & ¦ e    [11].

AlGaAs/GaAs ×  æ  ª  Ä ºÓ ü t ½ ¨ ¸  H 1.42 eV (873 nm) _   ½ × ¼Ì  s \  -t \  ¦ ° ú   H GaAs ü < 1.92 eV (645 nm) _   ½ × ¼Ì  s \  -t \  ¦ ° ú   H AlGaAs   §  $ í  © ÷ &# Q s

À Ò# Q4 R" f, GaAs ( J $ [ >  Ä ºÓ ü t`  ¦ + þ A$ í  ¦ AlGaAs

(

J $ [ >   © # 4 `  ¦ + þ A$ í   H ½ ¨ ¸ Ð s À Ò# Q4 R e    [12,13].

Al _   ¸$ í q Ö  ¦ s  Z  }   | 9 Ã º2  ¤     © Ã º_    o  H  _ 

\ O

Ü ¼   ½ × ¼Ì  s É r 7 £ x    H X < s \  ¦   ½ ÓÜ ¼ Ð   & ñ ~ ½ Ó ¾ Ó

$ í

Janghyun Cho · Yong-Sub Jung · Clare Chisu Byeon ^∗

bM ° Ë ÑÌ ¦ R8 ý û s ÚI í Ä ì Å× D; c Â \ ¥ AlGaAs/GaAs W ë s ¤ö n Ú º8 ý Photoluminescence ° Ë Ñ ¤V R Ë Ä Z ØV Ä

Ð ç ¡g ` @ · + ä ÷ 7 B) כ · _ @U ¬ £ ^∗

â

· ¡ ¤ @ / < Æ § l > / B N < ÆÂ Ò, @ /½ ¨ 702-701

B . > ò 6 B · T ª <A j

g Ö 6 x ½ + Ër Û ¼% 7 ½ ¨é ß ,ô Ç² D G õ < Æl Õ ü t ½ ¨" é ¶, " fÖ ¦ 136-791

(2013¸ 12 Z 4 13{ 9 ~ Ã Î6 £ §, 2014¸ 1 Z 4 19{ 9 Ã º& ñ : r ~ Ã Î6 £ §, 2014¸ 2 Z 4 12{ 9 > F S X & ñ )

MBE ~ ½ ÓZ O Ü ¼ Ð $ í © r AlGaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸\ " f # l F g _ Ø ¦§ 4 o\ É r F g µ 1 Ï F

g (photoluminescence, PL) : £ ¤$ í ` ¦ ì r$ 3 % i . n-type GaAs l ó ø Í0 A\ GaAs! Q( 8 £ x` ¦ + þ A$ í r Ê ê AlGaAs/GaAs\ ¦ ° ú 9 $ í © r r « Ñ\ # l F g _ Ø ¦§ 4 ` ¦ 20 mW \ " f 140 mW t or v

9 8 £ ¤& ñ % i . 803 nm, 812 nm\ " f 2> h_ PL 4 x Ä ºo © s ' a8 £ ¤ ÷ &% 3 Ü ¼ 9, # l F g _ Ø ¦§ 4 s 7 £ x

< Ê\ PL [ jl + þ A& h Ü ¼ Ð 7 £ x % i ¦, PL 4 x Ä ºo © s 5 nm & ñ ¸ & h Ò o¼ # s z ¤ .

Ò o¼ # s & ³ © _ Å Ò" é ¶ É r # l F g [ jl _ o\ É r AC Stark ´ òõ \ _ ô Ç \ -t ½ × ¼½ ¨ ¸_ 121

Keywords: F g µ 1 Ï F g , AlGaAs/GaAs × æ ª Ä ºÓ ü t, & h Ò o¼ # s

III-V7 á ¤ " é ¶ è_ ½ + Ë GaAs H Si l ì ø Í_ ì ø Í ¸^ ü < q

§ # Z } É r s 1 l x ¸, V , É r ½ × ¼Ì s, Z } É r Å Ò Ã º % ò

i \ " f_ & h É r ¸s Ý ¼, f ] X ½ × ¼Ì s 1 p x _ © & h ` ¦ ° ú ¦ e

# Q LED [1], 0 A$ í : x [2], Y Us $ [3], ¦ s 1 l x ¸ à

Ô ½ t Û ¼' (HEMT) [4] 1 p x ª ô Ç 6 £ x6 xì r \ " f ½ ¨

' ÷ &# Q M ® o . s Qô Ç ½ ¨ H ] j / B N& ñ _ µ 1 Ï õ 8Ô ¦

Q $ í © % i H X <, è+ þ A o, ¦| 9 & h o, ¦´ òÖ ¦$ í ` ¦ Æ Ò½ ¨ 9 8 ¦ ! 9î r Ó ü t| 9 ] j l Õ ü t x 9 èF > hµ 1 Ïs '

& ¦ e . : £ ¤ y , ] j Ó ü t _ ß ¼l ¸é ß 0 A Ð t ,

ª ½ ¨5 Å q ´ òõ > ÷ & H X < s Ð # ¸ : £ ¤

s F g < Æ : £ ¤$ í 1 p x s l > r _ Z O ß ¼ Ó ü t| 9 [ þ t õ H B Ä º Ø

Ô> è ß . ª & h [5], ª Ä ºÓ ü t [6], ¸ü <s # Q [7]

x þ j H Y > ¸ ç ß ª ½ ¨5 Å q ´ òõ \ ¦ 6 £ x6 x 9 H ½ ¨ '

÷ &# Q M ® o [8]. ª Ä ºÓ ü t ½ ¨ ¸\ ¦ ° ú H Y Us $ [9], I ª

t [10]ü < ° ú s 2 " é ¶ ª ½ ¨5 Å q ´ òõ \ ¦ ° ú H Ó ü t| 9 É r Õ ª

ºa ¸] X s " é ¶ 8 £ x é ß 0 A Ð ¸] X 0 p x ½ + É & ñ ¸_ ] j l Õ

t s µ 1 Ï² ú % i .

¤ y , ì r $ í © ~ ½ ÓZ O (molecular beam epitaxy, MBE) É r í ¦ / B N, q \ P ¨ î + þ A © I \ " f 7 £ x Ã Ì÷ & H ~ ½ Ód Ü ¼

Ð, Ô ¦í HÓ ü t _ D ¥{ 9 s & h ¦ $ : r \ " f $ í © s 0 p x 9, H

& h \ " f ç H{ 9 ô Ç \ x 8 £ x + þ A$ í s 0 p x ¦ ¸$ í s Ô ¦ í

HÓ ü t 0 l x ¸_ ] j# Q ç H{ 9 H © & h s e # Q ª Ä ºÓ ü t

¨ ¸\ ¦ ° ú H è ] j \ V , o s 6 x ÷ & ¦ e [11].

AlGaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸ H 1.42 eV (873 nm) _ ½ × ¼Ì s \ -t \ ¦ ° ú H GaAs ü < 1.92 eV (645 nm) _ ½ × ¼Ì s \ -t \ ¦ ° ú H AlGaAs § $ í © ÷ &# Q s

À Ò# Q4 R" f, GaAs ( J $ [ > Ä ºÓ ü t` ¦ + þ A$ í ¦ AlGaAs

J $ [ > © # 4 ` ¦ + þ A$ í H ½ ¨ ¸ Ð s À Ò# Q4 R e [12,13].

Al _ ¸$ í q Ö ¦ s Z } | 9 Ã º2 ¤ © Ã º_ o H _

Ü ¼ ½ × ¼Ì s É r 7 £ x H X < s \ ¦ ½ ÓÜ ¼ Ð & ñ ~ ½ Ó ¾ Ó

© s 0 p x ½ + É M : H& h ü @ @ /% i _ Y Us $ s ¸× ¼\ ¦ ë ß [

t Ã º e [9]. s % ! 3 AlGaAs/GaAs ª Ä ºÓ ü t ½ ¨ ¸\ ¦

H Y Us $ s ¸× ¼ H 6 £ x6 x é ß > \ e Ü ¼ 9, è Ð ] j

r z ´] j ½ ¨1 l x \ " f_ $ í 0 p x s \ V8 £ ¤ 0 p x ô Ç ½ ¨ '

&# Q ô Ç .

: r 7 Hë H \ " f H MBE ~ ½ Ód ` ¦ : x K $ í © r Al- GaAs/GaAs × æ ª Ä ºÓ ü t ½ ¨ ¸\ " f # l F g " é ¶ _ Ø ¦§ 4 [ j l

\ É r F g µ 1 Ï F g : £ ¤$ í ` ¦ ' a8 £ ¤ < ÊÜ ¼ Ð+ ü @Â Ò # l \ _ ô

Ç ² D G Â Ò& h \ -t ½ ¨ ¸ o\ ¦ ½ ¨ # , s Qô Ç ½ ¨ ¸

¦ 6 £ x6 x ô Ç è _ > hµ 1 Ï x 9 Ö ¸6 x` ¦ 0 Aô Ç l í & ñ Ð\ ¦ ] j /

N ¦ ô Ç .

1. GaAs quantum well S Å

´+ « >\ 6 x ô Ç Al _0.4 Ga 0.6 As/GaAs × æ ª Ä ºÓ ü t r « Ñ

H ì ø Í] X GaAsl ó ø Í © \ MBE $ í © ~ ½ ÓZ O Ü ¼ Ð $ í © ÷ &% 3

. MBE H Riber _ Compact21` ¦ 6 x % i Ü ¼ 9, Å Òì ø Í 6

£ xz ´ (main chamber)_ / B N É r ion getter pump x 9 cryo- genic pump Ð C l # $ í © \ 1.0 × 10 ⁻⁹ Torr s _

· ú § 4 , $ í © × æ \ 1.0 × 10 ⁻⁷ Torr _ í ¦ / B N · ú § 4 ` ¦

. r ¼ # _ ] j É r 6 £ § õ ° ú s ' ÷ &% 3 . ì ø Í] X

GaAs l ó ø Í` ¦ ¸{ 9 z ´ (load lock chamber) Ð V , ¦ 1.0

× 10 ⁻⁶ Torr _ / B N Ü ¼ Ð C l ô Ç Ê ê 100 ^◦ C \ " f

\ P ` ¦ z ´r % i . s Ê ê ï r q z ´ (preparation cham- ber) \ " f © l l ó ø Í` ¦ 400 ^◦ C s © \ P # ï r q z ´ /

N s 1.0 × 10 ⁻⁹ Torr s Ð ? / 9y ¤` ¦ M : l ó ø Í © _ ¸% i Ó

ü t| 9 s Ø æì r y Û ¼~ ½ ÓØ ¦ ÷ & ¸2 ¤ ô Ç Ê ê, Å Òì ø Í6 £ xz ´ Ð ì ø Í] X

GaAs` ¦ î r ì ø Í ¦, 620 ^◦ C \ " f As4\ ¦ ¸{ 9 # l ó ø Í

ð _ í ß oÓ ü t s Ø æì r y ] j ÷ & ¸2 ¤ % i . s M : l ó ø Í

ð _ í ß o} ] j H RHEED (Reflection high-energy electron diffraction) Û ¼ß ¼ 2 ; © \ " f " î Ñ þ ô Ç × ¦ Á º] ( + þ A J

s ` ¦ M : t ' ô Ç Ê ê l ó ø Í_ : r ¸\ ¦ 580 ^◦ C

Ð ? /o ¦ GaAs! Q( 8 £ x` ¦ 0.1 µm$ í © % i . $ í © Ê ê RHEED J © Ü ¼ Ð " î Ñ þ ô Ç 2 × 4J ` ¦ ^ ¦ Ã º e % 3 .

© ô Ç ½ ¨ ¸ H 6 £ § õ ° ú . l ó ø Í : r ¸\ ¦ 620 ^◦ C t

¦ 2 ; Ê ê © l ! Q( 8 £ x 0 A\ 10 nm ¿ ºa _ Al 0.4 Ga _0.6 As` ¦

© ¦, Õ ª 0 A\ 4.5 nm¿ ºa _ GaAsü < 5 nm¿ ºa _ Al 0.4 Ga 0.6 As\ ¦ 20 ì ø Í4 ¤ # $ í © % i . $ í © \ 6 x ô

Ç Ga x 9 Al/ B N/ å L" é ¶ É r VEECO \ " f / B N/ å L ô Ç SUMO K- cell s 9, As4/ B N/ å L" é ¶ É r Riber \ " f ] j/ B N ô Ç 6 \ Ú Ô © Ã Ì \ P ì

r W+ þ A As cell (VAC 500)s . GaAs x 9 AlGaAs_ $ í © Ò

¦ É r y y 0.141 nm/s, 0.094 nm/ss .

2. PL ¤X N Ë

¡" f ï r q ô Ç ª Ä ºÓ ü t ½ ¨ ¸ AlGaAs/GaAs r ¼ # _ \

-t ½ ¨ ¸ ì r$ 3 ` ¦ 0 A # F g µ 1 Ï F g (PL) \ _ ô Ç F g: £ ¤

ì r$ 3 ` ¦ ' % i . F g µ 1 Ï F g z ´+ « > É r SPECTRO _ Mmac200 (f = 200 mm) ì rF g l ü < PM100U photomul- tiplier tube (PMT)\ ¦ s 6 x # ½ ¨$ í % i ¦, F g " é ¶ Ü ¼ Ð H

s ¸× ¼ Y Us $ (λ = 532 nm)\ ¦ 6 x # z ´+ « > % i .

III. + s ÇÊ Ý õ m Í w ² o