rjtenmy@ipc.shizuoka.ac.jp
ZnO RPE-MOCVD UV- ZnO MQW LED/PD
& Energy harvesting LED ( ) PV & ZnO...
1970 1980 1990 2000 2010 SAW NTT ZnO LN, LT IC PbInAu/PbBi Nb PIN/FET LD/HBT 0.98-1.06m InGaAs QW-LD 2007 MOMBE MOVPE InGaAs/InP GaAs/AlGs MOVPE CNT InGaAs Q-dot for Qbit (CREST) Graphene/CNT UV- ZnO LED/PD Intel 4040 Pentium 1Kb DRAM RPE-MOCVD SiO 2 EDFA WDM GaAs DH CW LD LD LED DARPA UNIX TCP/IP WWW IT Google iphone ipad
ZnO Bandgap (ev) 8 7 6 5 4 3 2 1 AlN GaN 6H-SiC InN BN ZnO MgO C (diamond) 3C-SiC CdO CdTe ZnS MgS MgSe ZnSe ZnTe CdS GaP CdSe Si GaAs InP 0 2.0 3.0 4.0 5.0 6.0 7.0 Lattice constant (A) Ge ZnO (a=3.15 c=5.12) Eg=3.3eV Eg Mg 2+ 0.57Å Zn 2+ 0.60Å Cd 2+ 0.74Å MgZnO ZnO r B =1.8nm ZnCdO. GaN (a=3.25 c=5.21)3.4ev Al 3+ 0.39Å, Ga 3+ 0.47Å, In 3+ 0.80Å r B =2.2 nm 60 mev vs GaN 25meV
RPE-MOCVD ZnO L-MBE PLD), MBE, PA... MOCVD MOCVD 2 DH EL p (r )
O 2 cathode RPE-MOCVD PC DEZn, DMCd anode spectrometer quartz view window EtCp2Mg quartz guide tube jet zone matching circuit 13.56MHz substrate heater thermo couple 5 sccm 5 sccm RF0-50 W 0.01 Torr 300-800 O2 DEZn, DMCd + H2 TMIn, Cu(dibm) 2
a c ZnO c - c : 1.299 nm ZnO a x 4 : 1.300 nm - 0.08%, r a ZnO c SiC (p-4h-, 8off) ZnODH 4.9% a 3 c r a 2 a 1 a
Intensity (arb. units.) OH O 2 plasma/h 2 carrier O 2 plasma/n 2 carrier O OH Hα N 2 N 2 NO N 2 O 2 200 300 400 500 600 700 800 Wavelength (nm) H 2 Carrier gas O *, Hα * radicals N 2 Carrier gas O 2*, N * 2, NO *
PL 100 Mg 0.18 Zn 0.82 O RT Transmittance (%) 0 100 0 100 0 100 ZnO Zn 0.86 Cd 0.14 O Zn 0.70 Cd 0.30 O Normalized PL intensity 0 100 Zn 0.47 Cd 0.53 O 0 1.5 2.0 2.5 3.0 3.5 4.0 Photon energy (ev)
Zn(Mg,Cd)O 4.5 4.0 This work Review(Chen et al.) Wurtzite This work PLD(Makino et al.) E g 1.8-3.7 ev E ( x) = E (0)(1 x) + E (1) x bx(1 x) g g g Optical band gap (ev) 3.5 3.0 2.5 2.0 1.0 0.8 0.6 0.4 0.2 0.0 0.2 0.4 0.6 0.8 1.0 Mg content, y Cd content, x E ( x ) = 3.28(1 x ) + 2.3 x 3.04 x (1 x ) g,zncdo E ( y ) = 3.28(1 y ) + 7.8 y 3.47 y (1 y ) g,mgzno E g α 2 b ZnCdSe 0.5 InGaN 2.5 ZnCdO 3.0 MgZnO 3.5
PL PL peak energy (ev) FWHM (mev) 3.5 3.0 2.5 2.0 1.5 200 100 0 20 K Normalized PL intensity 20 K 0.55 0.30 0.19 0.18 0.11 x=0 0.0 0.2 0.4 0.6 0.8 1.0 Cd content 1.5 2.0 2.5 3.0 3.5 Photon energy (ev) Experiment Calculation PL 240 mev (x=0.19) In 0.5 Ga 0.5 N 200 mev @15 K (Zimmermann ) ( ) ( ) ( ) deex x V0 x ( x) = 2 2ln2 x( 1 x) dx Vex x E ex (x): PL V 0 (x): ( ) 3 V ex (x): V ( x) = 8π r x r b (x): ex B
MQW ZnO 30 nm 10 MQWs ZnCdO : 2 ~ 21 nm ZnO : 10 nm ZnO 100 nm a XRD steady-state PL @ 20 K PL @ 8 K
PL L W = 2 nm ZnCdO 20K ZnO : He-Cd - 325 nm - 35 mw/cm 2 Normalized PL intensity 4 nm 8 nm 11 nm PL 21 nm Zn 0.85 Cd 0.15 O bulk 140nm 2.0 2.5 3.0 3.5 Photon energy (ev)
PL emission energy (ev) PL FWHM (mev) 3.00 2.95 2.90 2.85 2.80 2.75 300 250 200 150 100 50 0 0 5 10 15 20 25 bulk 140 Well width, L W (nm) 20 K Experiment Calculation L W < 4nm energy (ev) E c / E v = 64/36 E c E v E e E h L w ZnOZnCdOZnO h 4 nm (~ : 1.8 nm) - / e
PL lifetime, τ 1, τ 2 (ps) Oscillator strength, f 100 80 60 40 20 0 1.5 1.0 0.5 τ 2 τ 1 0.0 0 5 10 15 20 25 bulk 140 Well width, L w (nm) 8 K τ 2-55 ps (L W 2nm) ~ 70 ps (L W 8nm) ( ) 3 πε mc f 2 1 = ne % τ 0 0 2 2 ω τr R f = 1.3 (L W 2nm) ψ ( x) 2 f, (τ R = τ 2 ) J. Feldmann et al., Phys. Rev. Lett. 59, 2337 (1987).
LED(DH ) RGB-EL R n-mgzno n-zn 1-y Cd y O p-sic Cross section G B EL intensity FWHM=146meV34meV 400 500 600 700 800 Wavelength (nm) A. Nakamura et al., APL 90(2007) 093512 EL (2 )
SiO 2 /Si CVD Ni, Cu ( )C 2 H 2,- - -, SiC SiC SiC+O 2 SiO+C TEM... 532nm Graphene HOPG D G 2D
Ni ACVD Layer number of exfoliated graphene 1 23 4 68 over 10layers (a) (b1) segregated graphene I G /I 2D = 0.202 W 2D =31.3cm -1 2708cm -1 2D FWHM W 2D (cm -1 ) exfoliated graphene layer segregated graphene layer Intensity (arb.units.) (b2) exfoliated graphene I G /I 2D =0.223 W 2D = 35.2cm -1 2674cm -1 2D I G /I 2D Raman Shift (cm -1 ) (a) (b) (c) 3 layers 4 layers 5layers 0.34 TEM 3-5 multilayer >10 3nm 2nm
CVD a-sapphire (a) (b) 800D G 2D 0.34nm Intensity (arb.units) 850 900 950 (c) 4nm (d) 2nm 1000 4nm 10nm 1200 1400 1600 2600 2800 Raman Shift (cm -1 ) (a) 900, (b) ) a-sapphire (c) (d) 1000
Sheet Resistance on Transmittance
RPE-MOCVD ZnO OH O 1.8eV3.7eV LEDMQW LED, Schottky-PD / 2 2007
2009.3.21