stem electron density　～ 1×1011 cm-2

Gate Voltage （ Vg ）　 0.0 ～ 0.8V

wire electron density

　 0 ～ 4×105 cm-

1

arm electron density

0 ～ 1.3×1011 cm-

2

Sample

1.5681.5641.560

Photon Energy (eV)

Phot

olumi

nesc

ence

Inte

nsity

(arb

.unit)

1.5701.5651.560Photon Energy (eV)

1μm step0.2μm step scanScan 1• Micro PL measurement with 1

μm / 0.2μm step automatic scanning enables us to find the center (blue circle) at every experiments.

Photon Energy (eV)

• Gate Voltage = 0.1V

• T=5K

• Stem well excitation with cw Ti:Sa laser (λ=750nm ) 0.2μW 、~1μm2 spot size

• Reflection geometry

• Resolution 0.15meV

wire trion PL

Phot

olumi

nesc

ence

Inte

nsity

(arb

.unit)

1.5901.5801.5701.560

Photon Energy (eV)

Phot

olum

ines

cenc

e In

tens

ity (a

rb.u

nit)

1.5901.5801.5701.560

Photon Energy (eV)

Phot

olum

ines

cenc

e In

tens

ity (a

rb.u

nit)

1.5901.5801.5701.560

Photon Energy (eV)

Scan 2 arm excitonwire trionGate Voltage = 0.1Vcheck all available aria with

~500μm ( 1.0μm step ) scanningPL

con

tinue m

ore

than

co

ntin

ue m

ore

than

5

00

μm

…5

00

μm

…

1.5701.5651.560Photon Energy (eV)

1.5701.5651.560Photon Energy (eV)

1.5701.5651.560Photon Energy (eV)

Phot

olum

ines

cenc

e In

tens

ity (a

rb.u

nit)

1.5701.5651.560Photon Energy (eV)

Vg=0.7V Vg=0.5V Vg=0.3V Vg=0.1V

0.5μm step scanning withvarious Gate Voltage ( Vg )scan 3

Photon Energy (eV)

→ 　 find the high quality aria (for example : blue arrow)

T=5K

PL

Phot

olum

ines

cenc

e In

tens

ity (a

rb.u

nit)

1.5701.5651.560

Photon Energy (eV)

Gate Voltage dependenceVg = 0V ～ 0.7V (0.05V

step)

corresponds

n1D = 0 ～ 4×105cm‐1

　 EFE = 0~1.8meV

①②

③

⑤④

①low electron density

→1.569eV exciton peak②trion peak : 2.3meV below exciton peak

(trion binding energy)

③high density 　→ band to band transition 、 electron plasma state

④Band Gap Renormalization(BGR)

⑤Fermi Edge Singularity(FES)

T=5KPL

1.5701.5651.560Photon Energy (eV)

1.5701.5651.560Photon Energy (eV)

1.5701.5651.560Photon Energy (eV)

Pho

tolu

min

esce

nce

Inte

nsity

(arb

.uni

t)

1.5701.5651.560Photon Energy (eV)

Temperature dependence

T=50K T=40K T=30K

Photon Energy (eV)

T=5K

①BGR at every temperature②ratio of exciton / trion peak

become large with temperature③FES disappear at high temperature

①①① ①

②②

③③

1.567

1.566

1.565

1.564

1.563

Pho

ton

Ener

gy (eV

)

0.80.60.40.20.0

Gate Voltage (V)1.5701.5651.560

Photon Energy (eV)1.5701.5651.560

Photon Energy (eV)1.5701.5651.560

Photon Energy (eV)

Pho

tolu

min

esce

nce

Inte

nsity

(arb

.uni

t)

1.5701.5651.560Photon Energy (eV)

Temperature dependence of Energy shift compare BGR at Gate Voltage 0.2V~0.7V 　　

5K

30K

40K

50K

Photon Energy (eV)

T (K) BGR(meV)

5 2.1

30 1.4

40 1.4

50 1.0

Small BGR at high temperature① ① ① ①

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0

FWHM

(meV

)

0.80.60.40.20.0

Gate Voltage (V)

・ trion peak （ Vg=0.2 ～0.3V ）

Temperature dependence of FWHM

5K

30K

40K

50K

Photon Energy (eV)1.5701.5651.560

Photon Energy (eV)1.5701.5651.560

Photon Energy (eV)1.5701.5651.560

Photon Energy (eV)

Pho

tolu

min

esce

nce

Inte

nsity

(arb

.uni

t)

1.5701.5651.560Photon Energy (eV) Photon Energy (eV)

T (K) FWHM(meV)

5 ～ 0.7

30 ～ 1.5

40 ～ 2.0

50 ～ 2.3

・ At high Gate Voltage (Vg=0.4V～）

temperature dependence of FWHM is very small④ ④ ④ ④

1.55 1.57 1.59 1.61 1.63 1.65

wire HH

PLE

PL

PL & PLE of wire

stem LH

stem HH

arm HH

Photon Energy (eV)

arm LH

PL

and

PLE

Inte

nsity

(ar

b.un

its)

1.5721.5681.564

Photon Energy (eV)

PL detection is perpendicular to the laser excitation to improve S/N ratio.Vg = 0.15V T = 5K

LH ： light hole

HH ： heavy hole

excitation

detect

polarization

PL

and

PLE

Int

ensi

ty (

arb.

units

)

1.5721.5701.5681.566

Photon Energy (eV)

0.0V

0.1V

0.15V

0.2V

0.3V

0.4V

①

②

③

①neutral exciton

(exciton)

②charged exciton

(trion)

③FES

PL

and

PLE

Int

ensi

ty (

arb.

units

)

1.5721.5701.5681.566

Photon Energy (eV)Photon Energy (eV)

Low density PLEPL

③

Gate Voltage　 0.0V ～ 0.4V

Theoretical work ： M. Takagiwa, T. Ogawa, 2001

density

density

nn1D1D

HH

LL

PL

and

PLE

Inte

nsity

(arb

.uni

ts)

1.5761.5721.5681.564

Photon Energy (eV)

PL

and

PLE

Inte

nsity

(arb

.uni

ts)

1.5761.5721.5681.564

Photon Energy (eV)

0.25V

0.35V

0.4V

0.5V

0.6V

0.7V

0.15V①Fermi Edge

②Band Edge

③ ？？？

①②

③High density

Photon Energy (eV)

PLEPL

Gate Voltage

　　 0.4V ～ 0.7V

electron plasma

Electron density dependence of PLE varies with the position of the wire.

PLE trion→electron plasma

1.564 1.566 1.568 1.57 1.572

0.30.350.40.450.5PL

1.564 1.566 1.568 1.57 1.572 1.564 1.566 1.568 1.57 1.572

Photon Energy [eV]

PL a

nd P

LE i

nten

sity

[arb

. Uui

ts] （ PLE ）

Vg = 0.3V

Vg = 0.35V

Vg = 0.4V

Vg = 0.45V

Vg = 0.5V

（ PL ）

Vg = 0.15V

PL

and

PLE

Int

ensi

ty (

arb.

units

)

1.5761.5721.5681.564

Photon Energy (eV)

PLE

PL

PLE

PL

PLE

PL

1.564 1.565 1.566 1.567 1.568 1.569 1.57 1.571 1.572

PLE （ Vg=0.15 ） and PL （ Vg=0.12 ） at different position of wire.

Resolution of PL : 0.15meV, PLE : 0.04meV 。

The gap between exciton peaks (or trion peaks) varies with electron density from 0.3meV to 0.5meV. This is probably due to stem well ML fluctuation (theoretical calculation : stem well ML fluctuation is ~0.3meV).

High resolution PLE

1.564 1.565 1.566 1.567 1.568 1.569 1.57 1.571 1.572

1.564 1.565 1.566 1.567 1.568 1.569 1.57 1.571 1.5721.564 1.565 1.566 1.567 1.568 1.569 1.57 1.571 1.572

PL a

nd P

LE i

nten

sity

[arb

. Uui

ts]

Photon Energy [eV]Photon Energy [eV]

PLEPL

PL

and

PLE

Int

ensi

ty (

arb.

units

)

1.5701.5681.566

Photon Energy (eV)

0.0V

0.02V

0.04V

0.06V

0.08V

0.14V

0.10V

0.12V

Exciton peak shifts with electron density : 3.5meV / V ( blue line ).

FWHM of PL spectrum (corresponds EF) changes ~ 3.5meV/V.

Trion peak doesn’t shift. Equation below can be

expected.

exciton shift

Fb EE 12

PLE

trion exciton2

1: exciton: trion

PL

and

PLE

Int

ensi

ty (

arb.

units

)

1.5761.5721.5681.564

Photon Energy (eV)

PL a

nd P

LE In

tens

ity (a

rb.u

nits

)

1.5881.5841.580

Photon Energy (eV)

1.1

0.8

0.2

1.5

1.8

2D （ arm 　 well ） / 1D well

①①

②

②

③

③ 0.5

wire EF

（ meV）

1.1

0.8

0.2

1.5

1.8

0.5

EF

（ meV）

④ ④① Eb

wire : Eb=2.3meV

well : Eb=1.4meV

② wire ： blue shift, rapid dampingwell ： blue shift, broadening

③trionabsorp

wire ： no shift, rapid dampingwell ： blue shift, broadening

④ wire ： large blue shiftwell : small blue shift begins from trion peak smoothly

excitonAbsorp.

plasmaabsorp.

V. Huard et al. Phys. Rev. Lett. 84 (2000) 187