? ????? t?? ??ast???? ??se?? st? ??ad??as?a ???pt???? ?a

1
? ????? t?? ??ast???? ??se?? st? ??ad??as?a
???pt???? ?aµ???d??stat?? ?µ?a?????

• ?a??at????? ??astas?a
• S.?.?.F.?., 10? e??µ???
• ??????? 2006
• ?pe????? ?a????t??a ?a. ?. ?apad?µ?t????

2
?e??e??µe?a

• ??ast???? ??se?? ?a?aµ??f?se??
• (Strain Stress)
• ?te??d?µ?? ?p? ??ast??? ?a?aµ??f?s?
• (Strained Heterostructures)
• ??t???a??µ??a ?ßa?t??? S?µe?a InAs/GaAs
• (Self-assembled Quantum Dots)
• ?p?d?as? t?? ??ast???? ?a?aµ??f?s?? ?a? t??
  ?ßa?t???? ?e?????sµ?? st?? ??µ? t?? ??e?t????a???
  ?????
• ?fa?µ???? 1.3 µm ???d??? Laser

3
??ast???? ??se?? - ?a?aµ??f?se??

• Xx c11exx c12eyy c13ezz c14eyz c15ezx
  c16exy sxx
• Yy c21exx c22eyy c23ezz c24eyz c25ezx
  c26exy syy
• Zz c31exx c32eyy c33ezz c34eyz c35ezx
  c36exy szz
• Yz c41exx c42eyy c43ezz c44eyz c45ezx
  c46exy syz
• Zx c51exx c52eyy c53ezz c54eyz c55ezx
  c56exy szx
• Xy c61exx c62eyy c63ezz c64eyz c65ezx
  c66exy sxy

4
??ast???? ??se?? - ?a?aµ??f?se??

• ? a???µ?? t?? e?ast???? sta?e??? µe???eta? se
  ???st??????
• µe ????? s?µµet??a. Se ???st?????? t?? ??ß????
  s?st?µat??
• 
  sxx c11exx c12eyy c13ezz (1)
• 
  syy c21exx c22eyy c23ezz (2)
• 
  szz c31exx c32eyy c33ezz (3)

exx eyy ezz eyz ezx exy
sxx c11 c12 c12 0 0 0
syy c12 c11 c12 0 0 0
szz c12 c12 c11 0 0 0
syz 0 0 0 c44 0 0
szx 0 0 0 0 c44 0
sxy 0 0 0 0 0 c44
5
??ast???? ??se?? -?a?aµ??f?se??

• ?p? t?? ep?d?as? ?s?t??p?? d?a??????? t?se?? st?
  ep?ped?
• sxx syy s (4)
• szz 0 (5)
• (1),(2),(4) ? (c11 c12)exx (c11 c12)eyy ?
  exx eyy e (6)
• (3),(5),(6) ? 2c12exx c11ezz 0
  ? ezz -(2c12/c11) e (7)
• (1),(6),(7) ? s (c11 c12)e (2c122/c11) e
  

6
?te??d?µ?? ?p? ??ast??? ?a?aµ??f?s? (Coherent
Incoherent Growth)

• ?? ta d?? ????? d?af????? ?? p??? t?? p?e?µat????
  sta?e??? t??? as, aL (lattice mismatch),
  eµfa?????ta? e?ast???? t?se??-pa?aµ??f?se??
• e (as aL) / aL
• O? t?se?? e??a? µ???ste? ?at? t? s?µf???
  (coherent) ?a? e????ste? ?at? t? µ?-s?µf???
  (incoherent) a??pt???.
• ?? t?se?? ?a?a?????? µe t? d?µ??????a e?a?µ?se??.

7
?te??d?µ?? ?p? ??ast??? ?a?aµ??f?s? (Coherent
Incoherent Growth)

• ???s?µ? p???? dc ? as / 2?e?
• ??a p??? µ????te?a ap? dc ,
• ? ep?st??s? a?apt?sseta? ????? e?a?µ?se?? ?a?
  e??a? ?p? t?s?.
• ??a p??? µe?a??te?a ap? dc ,
• ? ep?st??s? eµfa???e? a????? e?a?µ?se??. St?
  s????e?a, a?apt?sseta? ????? t?s? ?a? µe t??
  e?e??e?? p?e?µat??? sta?e??.

8
?te??d?µ?? ?p? ??ast??? ?a?aµ??f?s? (Coherent
Incoherent Growth)

• ?a??de??µa
• ?? ???s?µ? p???? ??a a??pt??? In0.3Ga0.7As se
  ?p?st??µa GaAs e??a?
• ? p?e?µat??? sta?e??, s?µf??a µe t? ??µ? t??
  Vegard e??a?
• a(In0.3Ga0.7As) 0.3aInAs 0.7aGaAs 5.775
  Å
• ? pa?aµ??f?s? e??a? e
  (5.653 5.775) / 5.775 - 0.022
• ?? ???s?µ? p???? e??a? pe??p?? dc 5.653
  / 2(0.022) 128 Å

9
?aµ???d??stat?? ?µ?a?????

• O? f?s???? ?d??t?te? p??sd???????ta? ap? t??
  d?ast?se?? t?? s?st?µat??.
• ?e???? ???µa?a? a ltlt ? ltlt L , a d??µet???
  at?µ?? ? µ?????
• 
  ? µ?s? µ???? e?e????a? d?ad??µ?? e-
• 
  L µ??e??? d???µ??? (lt100 nm 1000 A)
• Fa???µe?a ?ßa?t???? pe?????sµ?? L lt 100 Å
• 2D ?ßa?t??? p???d?a (Quantum Wells) ?a?
  ?pe?d?µ??
• L1, L2 L3 0
  (L1, L2 gtgtL3
  quasi 2D)
• 1D ?ßa?t??? ??µata (Quantum Wires)
• L1 L2 L3 0
  (L1gtgtL2 , L3
  quasi 1D)
• 0D ?ßa?t??? s?µe?a (Quantum Dots)
• L1 L2 L3 0
  (L1, L2 , L3 ? 0
  quasi 0D)

10
?p?d?as? t?? ??ast???? ?a?aµ??f?s?? st?? ??µ? t??
??e?t????a??? ?????

• VB e?e??e?a?? µetat?p?s? ?a? ??s? e?f???sµ?? (HH
  LH)
• ?? ap?t??esµa e?ast???? t?se??/pa?aµ??f?se??

11
?p?d?as? t?? ??ast???? ?a?aµ??f?s?? ?a? t??
?ßa?t???? ?e?????sµ?? st?? ??µ? t?? ??e?t????a???
?????

• VB e?e??e?a?? µetat?p?s? ?a? ??s? e?f???sµ??
  (HH LH)
• ?? ap?t??esµa t?? ?ßa?t???? pe?????sµ??
• VB epa?af??? t?? e?f???sµ?? (HH LH)
• ?? ap?t??esµa e?ast???? t?se??/pa?aµ??f?se??

12
??t???a??µ??a ?ßa?t??? S?µe?a(self-assembled
quantum dots)

• Layer by layer (e ? 2)
• Stranski-Krastonow
• Island growth mode
• ?e t?? s??µat?sµ? ??s?d??,
• ? e?a??st?p??e?ta? ? e????e?a pa?aµ??f?s??
• ? d??eta? ? d??at?t?ta a??pt???? s?st?µ?t?? 0D
  (QD) ????? ???s? ??????af?a?, e????a??? ??p.

13
?p?ta??a?? a??pt??? QD InAs se ?p?st??µa GaAs

• Se ?e?µ???as?a 600?C TMIn H3As ? InAs
  p?????ta

14
???s?µ???s? ??ast???? pa?aµ??f?s??

• ?e a???µ?t??? p??s?µ???s? ?aµß??eta? ?
  pa?aµ??f?s? t?? de??µat?? se 3 d?ast?se??.

15
???s?µ???s? ??ast???? pa?aµ??f?s??

• ? ?ata??µ? t?? t?s?? de? e?a?t?ta? ap? t? µ??e???
  t?? ?ßa?t???? s?µe???, a??? ?????? ap? t? s??µa
  t??.

16
??e??e?a??? µetaß?se?? se??t???a??µ??a ?ßa?t???
s?µe?a InAs/GaAs

• In ? 0.4
• ? pa?aµ??f?s? e??a? 7
• ?g InAs 1.164 eV (????? t?s?)
• Eg dot ? 1.060 eV

17
?fa?µ???? 1.3 µm ???d??? Laser

• Total light output and lasing spectrum (inset)
  for
• MBE GaAs-based QD laser

18
?fa?µ???? 1.3 µm ???d??? Laser

• transparency current density 40 A/cm2
• 5 W output power(100 µm stripe), 300 mW(7 µm)
• stability enhancement
• improved radiation hardness
• suppressed facet overheating
• modulation bandwidths gt10 GHz (7.4 GHz at RT)
• passive mode-locking in the range 550 GHz

19
ß?ß?????af?a

• M.Grundmann, O.Stier, D.Bimberg, Phys. Rev. 52,
  number 16 (1995).
• D. Bimberg, M. Grundmann, N.N. Ledentsov, M. H.
  Mao, Ch. Ribbat, R. Sellin, V. M. Ustinov, A. E.
  Zhukov, Zh. I. Alferov, J. A. Lott, Phys. Stat.
  Sol. (b) 224, 787 (2001).
• D. Bimberg, M. Kuntz, M. Laemmlin,
  Microelectronics Journal 36, 175 (2005).
• Jasprit Singh, Electronic and optoelectronic
  properties of semiconductor structures,
  (Cambridge University Press 2003).
• Charles Kittel, Introduction to Solid State
  Physics (4th edition, New York 1971).
• Peter Y.Yu, Manuel Cardona, Fundamentals of
  semiconductors physics materials properties,
  (Springer Verlag, Berlin 2001).