?????????????????????PL???????????????????????????????????????????????????????????????????????????????????

1
?????????????????
????? ?????????
?????????????????????PL???????????????????????????
??????????????????????????????????????????????????
?????? ?????????n??????????FET??????????PL???PLE??
?????????????????????????????????????????????????
????????????????I-V???EL?PL????????????
2
???????????????????????
??????????????????????????? (1980????????????)
T?????????????????????????????????????????????????
??????????(1993?Wegscheider?) ????????????????????
??????? (1997?Ambigapathy ?) V????????????????????
????? (2000?Sirigu?) T??????????????? ???????????
(2001?Rubio?) ???T???????????? ??????????????????
??????????????? (2003????)
3
cf Wegscheider et al. PRL 1993
?????????????? ????????????????
cf Rubio et al. SSC 2001
4
???????PL?????(???????)
aB 13nm
n1D 1.2 x 106 cm-1 (rs 0.65 aB)
Electron-hole Plasma
Density
n1D 1.2 x 105 cm-1 (rs 6.6 aB)
BiexcitonExciton
EB 2.8meV
n1D 3.6 x 103 cm-1 (rs 220 aB)
Free Exciton
n1D 102 cm-1
M. Yoshita, et al.
5
Plot
6
Exciton band edge plasma band edge (T30K)
? plasma band edge (low energy edge of plasma
PL) starts at biexciton energy and
shows red shift.
? exciton band edge, (onset of continuum
states) exciton ground and excited
states show no shift.
7
???????????????????
Single wire laser, uncoated cavity mirrors
Excitation Light cw TiS laser at 1.631eV
Spectrometer with spectral resolution of 0.15 meV
Point
WaveguideEmission
Polarizationparallel toArm well
8
???????????(???????)
Excitation Light cw TiS laser at 1.631eV
Spontaneousemission
Spectrometer with spectral resolution of 0.15 meV
Stripe shape
Cassidys Method
WaveguideEmission
8.3mW
Polarizationparallel toArm well
9
?????????????????????
Electron-Hole Plasma

• Generation of gain and e-h plasma formation
• Large excitonic absorption non-linearity
• ?a/a17/105cm-1

Exciton
Hayamizu et al.
10
20????????????????
?????????????????
??????????????? ???????? 1D DOS????
11
20??????????????????
??????
????
???????? ??????
??120K (????) ??????? Arm well?????
(?????????)
12
?????????? by Huai and Ogawa (2005)
13
14nmx6nm ????????? FET ????????1D???????????
??
????
T. Ihara et al.
14
?????????????????????????? (???????)
????????
??
1?? ???
?
Huard et al., PRL 84, 187 (1999)

• ????????
• Fermi Filling?Screening???
• ?????(exciton?trion?FES??????????)

15
???????_at_ 5K (1D?2D)
16
?????(?????) (1D?2D)
????FE?????BE???????????
17
?????????????
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
??? 1) ???????n?????????????????????????????????
???? 2) ??????????????????????????????????????????
??????????????????????????????????????????????????
?1???????????????????????????? 3)
n??????????FET????????1???????????????????????????
????????????????????????????????????????? 4)
??????????????????????????????????????????????????
??????????????????????????????????????EL??????I-V?
??????????????????????????????????????????????????
??????????????????
22

• ??-??????????
• ?????????-????????????????????
• ???????????? ??????
• ????????????
• ????(???)???????????
• ???(JST???)???????
• ????(??)??????????????
• ???(DC)??-??????????
• ???(???????)
• ???(??????)
• ??????????
• ? ????????
• ? ?????(???)?????(??)
• ? ???Mott?????/???,????
• ? ??-?????(BEC?BCS)???/???
• ? ???????????,????

23
Lasing many-body effects in quantum wires
E. Kapon et al. (PRL89) Lasing in
excited-states of V-wires W. Wegscheider et al.
Lasing in the ground-state of T-wires, no energy
shift, (PRL93) excitonic
lasing R. Ambigapathy et al. PL without BGR,
strong excitonic effect in V-wires
(PRL97) L. Sirigu et al.
(PRB00) Lasing due to localized excitons in
V-wires J. Rubio et al. (SSC01) Lasing observed
with eh plasma emission in T-wires A. Crottini
et al. (SSC02) PL from exciton molecules
(bi-excitons) in V-wires T. Guillet et al.
(PRB03) PL, Mott transition form excitons to a
plasma in V-wires Y. Hayamizu et al. (APL02)
Single-mode lasing in a single T-wire H. Akiyama
et al. (PRB03) Lasing due to eh plasma, no
exciton lasing in T-wires H. Yagi et al. (Arai
group, RT-CW GaInAsP/InP wire lasers by etching
regrowth
TIT)(JJAP03) (23nmx7nmx5layers,
100mA,800A/cm2,36,lt10000h) F. Rossi and E.
Molinari (PRL96) F. Tassone, C. Piermarocchi, et
al. (PRL99,SSC99) S. Das Sarma and D. W. Wang
(PRL00,PRB01)
Theories
1D exciton Mott transition
24
????????? (JST-CREST02-07)
???????????? ???????? ???????? ???????
???? ????????? ?????????
???????
??????????????????????????
?????(?????)?????????????
25
Absorption/gain measurement based on
Hakki-Paoli-Cassidys analysis of
Fabry-Perot-laser emission below threshold
Absorption coeff.
Reflectivity
D. T. Cassidy JAP. 56 3096 (1984)
Free Spectral Range
B. W. Hakki and T. L. Paoli JAP. 46 1299 (1974)
26
Previous works of absorption spectra in quantum
wires
Numerical calculations
27
Physical picture of 1D excitonplasma transition
the exciton Mott transition
Our PL results show
Increase of eh pair density causes
reduction of exciton binding energy red
shift of the band edge (band-gap
renormalization (BGR))
eg. D. W. Wang and S. Das Sarma, PRB 64,
195313 (2001).
band edge
exciton level
28
F. Rossi et al. (PRL96)
Quasi-equilibrium optical absorption
Polarization equation
Without Coulomb
A 1 x 104 B 5 x 105 C 1 x 106 D 4 x 106
cm-1
Coulomb correlations
0

• Suppression of band edge
• Mott transition at 1 x 106
• Modification of absorption spectra by Coulomb
  correlations

Room temperature
With Coulomb
29
F. Tassone et al. (PRL99)
Self-consistent ladder approx. (SCLA)
electron
hole
Same mass
Missing long-range effects

• Excitonic gain at n 0.21
• Gain due to e-h plasma at high density
• Blue shift of BGR

Gain peak
Exciton PL peak
It is difficult to evaluate BGR from PL.
30
(No Transcript)
31
Dynamical Bethe-Salpeter equation

• No gain
• Absence of Mott transition

D. W. Wang et al. (PRB01)
7 x 7 nm T-wire, T10K
32
D. W. Wang et al. (PRB01)
33
PL spectra in a V-groove quantum wires
R. Ambigaphthy, et. al. PRL 1997
34
L. Sirigu et al. (PRB00)
PL spectra T10K
V-wires
35
PL spectra in a V-groove quantum wires
T. Gullet et. al. PRB 2003
36
T. Guillet et al. (PRB03) Mott transition form
an exciton gas to a dense plasma

in very-high-quality V-wire
37
Jpn. J. Appl. Phys. Vol. 42 (2003) L748-L750 Room
Temperature-Continuous Wave Operation of
GaInAsP/InP Multiple-Quantum-Wire Lasers by Dry
Etching and Regrowth Method H. Yagi, T. Sano, K.
Ohira, T. Maruyama, A. Haque and S. Arai Tokyo
Institute of Technology, CREST, JST
38
20???????????????
T?????????????????????
??????
??????????
60K???
20??????????
150K???
39
??????????????????
Arm well
Arm well
??????????????????Arm well??????????
40
Absorption at higher temperatures by Cassidy
Hayamizu et al. unpublished
41
Evolution of continuum
Takahashi et al. unpublished