GaAs T?????????

1
?????_at_??????????? (2004.10.9-11)
GaAs T????????? ?????????
??? ????
2
????
?????????
???
???
( d gtgt aB )
( d ltlt aB )
(aB ???????)
?????? ???
???????????
???
???Mott?????
3??(or 2??)?
?????????? (band-gap renormalization??)
????????????
1???????
????????
3
1???????????????
1??????????

• ???????????
• ???????? ---- ?????????????

?????????
R. Ambigapathy et al. BGR???????? ??????????
(PRL97) A. Crottini et
al. (SSC02) ?????????? T. Guillet et al.
(PRB03) ?????????????????????????
????????????????
E. Kapon et al. (PRL89) V??????????????????? W.
Wegscheider et al. T??????????????????
(PRL93) ????? L. Sirigu et al.
(PRB00) ?????????????? J. Rubio et al.
(SSC01) ???????????????????

H. Akiyama et al.
????????????????? (PRB03)
4
????
??????T?????????????????????????????

• 1??????????????????
• ?????????????????
• 1?????????Mott?????
• ????????????

5
T???????
??T?????????
??????MBE??????????
T????????
???? ????
???
ref ??T????????????????????? by Y. Hayamizu
et al., APL 81, 4937 (2002).
6
T?????????????????
T5 K
scan step 0.5 mm scan length 25 mm
No monolayer fluctuation
gt 20 mm
linewidth lt 1.3 meV (cf. previous T wires
10 meV)
7
???????-???????
????????????????????????????????????????????
?????????
?????????
????
(slit?????????????)
8
????????????????? (T4 K)
??? ??????? 0.8 mm ???????? 1.6146 eV
(arm????)
?? CCD binning???????????????????
????? ??????0.8 mm (CCD pixel
limit) ??????0.8 mm (?????
limit)
???????????
9
???????????????
(???????)
???????????
??????????????????
10
??????????(I)
??PL??
???????? vs. ?????
pl
plex
biexex
11
??????????(II)
????????????
pl
plex
biexex
12
??????????
above 510-2 mW (higher density regime)
High

• ?????????? (????????)

around 2-510-2 mW (high density regime)

• ???????
• ????????????????
• ???????? ????????

????
around 10-2 mW (intermediate regime)

• ???????????????????
• ??????? ??????? 2.8 meV
• superlinear???

below 10-4 mW (low density regime)
low

• ????????(1.582eV) 1???????

13
???????????????????

• ??????????????????????????????????????????

(1) ????????
n1D 3.6 x 103 cm-1 (rs 220 aB)
??????? 2.8 meV
(2) ???????????
n1D 1.2 x 105 cm-1 (rs 6.6 aB) ???????????????
????

• 1D ???????????

(1) ??????????????????( lt 2meV )
(2) ??????????????????
(3) ????????(????1D-DOS?????????)
??????????????????
( ???????????? )
14
??????????????(T30K)
???????????????
excited ????????(1.589 eV)
onset ???????????????
?????????? (?? by
Itoh)
15
????????????????

• ????????? (?)

?????????????????????

• ?????????????? (?)

• (1) ?????? BGR????
• cf. ????? --- no energy shift
• ????????????????????
• (3) ????????????????????????

• ?????????2??????????????

16
1D???-????????????
???Mott?????
??????
????????????

• ????????(????)
• ?????????????

?????red-shift (BGR) ????????????

• ???????????????
• ?????????????BGR
• ????

eg. D. W. Wang and S. Das Sarma, PRB 64,
195313 (2001).

• ???????????????
• ???????????????
• ???????????

band edge
exciton level
?
????????????? ???????
17
T??????????????????
?????????
1???????
???????
???
???
?????????
lt??gt
n???????
1?????
18
Cassidy???? ?????????
T 5K
Electron-Hole Plasma
by ??
???????????

1. ????????????????????????????????
2. ???????????????????????

Exciton
???????????(??) ?????????(??)
19
???????????????????
by ??(?)
???????????????
??????????????????????
???? (cm-1)
Ith
0.8 Ith
Energy (eV)
20
n-doped 1D wire (by ??)
Ef6meV
?????
??????????????
Ef2meV
me0.067m0 mh 0.105m0
?????
FE?Trion?????????????????????????????????????
?????
?Trion????????Eb2meV
21
???
?????T?????????1???????????????????????????

1. ??????????????????????????????????????????
2. ????????????????????????????????????
3. ????????????(??????????)??????????
4. ????????????????????????????????????????

???Mott?????????????? ----
??????????!!
22
(No Transcript)
23
?????_at_??????????? (2004.10.9-11)
GaAs T????????? ?????????
??? ????
24
????
??????T?????????????????????????????

• 1??????????????????
• ?????????????????
• 1?????????Mott?????
• ????????????

25
????????????????? (T4 K)
?????????????????????
?????????????????????????????????
26
????????????????? (T4 K)
27
??????????????(T30K)
???????????????
excited ????????(1.589 eV)
onset ???????????????
??????????
28
????
?????????
???
( d gtgt aB )
( d ltlt aB )
???
?????? ???
???????????
???
1???????
???Mott?????
?????????? (band-gap renormalization??)
????????????
????????
29
(No Transcript)
30
?????????
MBE????????????????????????????????T?????
(???????1D limit????)
????? ?stem well????Si?????????????????????????w
irearm well?????1??2?????????
?????? ????????????????????????????????????????
?????????????????PLE?S/N????(?)?
?PLE??????????????????????????????????
??????????5K???
31
???????????(????)
32
???????????????????
by ??(?)
???????????????
??????????????????????
?????20 cm-1
???? (cm-1)
Energy (eV)
33
?????????
(by ???)
?????????????1.6 meV?
T-wire ???? arm ??????
??????????
20????????????
arm ??
arm ??
stem ??
???? (cm-1)
???? (cm-1)
Energy (eV)
Energy (eV)
34
(No Transcript)