1 薄膜生长
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(1) island (Volmer-Weber) (2) layer (Frank –Van der Merwe) (3) layer-island (Stranski-Krastanov)
Three Basic Growth Modes
Ag on NaCl
Transmission electron microscope images of nucleation, growth, and coalescence of Ag films on (111) NaCl substrates.
STM
Scanning tunneling microscope image of Si deposition on three successive terraces. Field of view is 300 A x 300 A.
STM
Arrhenius plot of island density vs the reciprocal of the substrate temperature.
Experimental Studies of Nucleation and Growth
1 TEM, SEM 2 AES 3 STM, AFM
AES
Schematic Auger signal currents as a function of time for the three growth modes. (a) island, (b) planar, (c) S-K. o = overlayer, s = substrate.
STM
Scanning tunneling microscope images of deposited metal clusters, Ag nuclei on (111) Si
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
Lennard-Jones Equation
E = Ep[( ) − 2( ) ] r r
12 6
rp
rp
Chemisorption
Chemical Bond
Electrovalent Bond Covalent Bond Metal Bond
Chemisorption
Condensation and Diffusion
∆T = Tm[1− exp(−
*
2σ1Vm r =r = kT ln P / P r
2σV )] Lr
2σTmV rL
Tr ∆T σ kT P = ln = 1− Tm σ1L P Tm r
Tm σ kT P = 1+ ln σ1L Tr P r metal
σ kT ≈1 , ≈ 0.1 σ1 L
Process of Thin Films Formation
Phase Transition
Gas, Liquid Atoms, Molecules Solid Films
kT P ∆F = − ln Vm P s
Absorption
Physisorption
Van der Waals Force
1 eV=23.1 kcal/mol =96.5kJ/mol
Physisorption
Van der Waals Force
Attractive Force
E = Ees + Eind + Edis
Repulsive Force
Er = B exp(ar) = Br
−m
Physisorption
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
Molecule He Ar CO Xe CCl HCl HBr HI H2O NH3 Ees 0 0 0.00021 0 0 1.2 0.39 0.021 11.9 5.2 Eind 0 0 0.0037 0 0 0.36 0.28 0.10 0.65 0.63 Edis 0.05 2.9 4.6 18 116 7.8 15 33 2.6 5.6 E(kJ/mol) 0.05 2.9 4.6 18 116 9.4 16 33 15 11
Condensation and Diffusion
Equilibrium
dn n = N ↓= dt τ n =ν nexp(−Qdes 1
τ
kT )
)
1 =ν exp(−Qdes 1
τ
kT
1 exp(Qdes τ=
ν1
kT
)
Condensation and Diffusion
1 Interaction of Adatoms 2 Migration of Adatoms
Ag on NaCl
Transmission electron microscope images of nucleation, growth, and coalescence of Ag films on (111) NaCl substrates.
Au on NaCl
TEM micrographs of Au/NaCl(001) formed at T=250 oC, R=1013 atoms cm-2s-1 and deposition times of (a) 0.5, (b) 1.5, (c) 4, (d) 8, (e) 10, (f) 15, (g) 30 and (h) 85 min.
Repulsive Force
Van der Waals Force
Electrostatic Force
2µ µ 1 Ees = − 2 6 3kT (4πε0 ) r
2 2 1 2
Van der Waals Force
Induced Force
Eind = − 1 (4πε0 )
2
(
α2µ12 +α1µ22
N ↓ enough high, condensation
Condensation and Diffusion
X = 2Ddτ = Dd = a ν exp(−
2
2Dd
ν1
Qdif
Q exp( des )
2kT
)
kT ν Qdes − Qdif X = 2a exp(
ν1
2kT
)
Three Basic Growth Modes
Chemisorption
Chemical Bond
Physisorption Van der Waals Force
Attractive Force
Electrostatic Force (Keesom) Induced Force (Deby) Dispersion Force (London)
Au on NaCl
TEM micrographs of Au/NaCl(001) formed at T=250 oC, R=1013 atoms cm-2s-1 and deposition times of (a) 0.5, (b) 1.5, (c) 4, (d) 8, (e) 10, (f) 15, (g) 30 and (h) 85 min.
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
AFM
Corresponding Auger spectra
Theories of Nucleation and Films Growth
Section I
Theories of Nucleation and Films Growth
1 Phase Transition 2 Absorption 3 Condensation and Diffusion 4 Three Basic Growth Modes of Thin Films 5 Experimental Studies of Nucleation and Growth
P / P = 102 , Tm / Tr = 1.5 r
Sintering
Successive electron micrographs of Au deposited on MoS2 at 400oC illustrating island coalescence by sintering, (a) Arbitrary zero time, (b) 0.06s, (c) 0.18s, (d) 0.50 s, (e) 1.06 s, (f) 6.18 s
dnd Qdes ∝ exp(− ) dt kT
dnd Qdes = υ1n exp(− ) dt kT
Condensation and Diffusion
Equilibrium
dn = N ↓ dt − n /τ dt = (N ↓ −n /τ )dt n = N ↓τ[1− exp(−t /τ )] when t →∞，n=N ↓τ
Accommodation Coefficient
E0 − Edesorbed T0 − Td αT = = E0 − Esubstrate T0 − Ts
0 ≤ αT ≤ 1
Condensation and Diffusion
1) Desorption Rate
dnd ∝n dt
E>Qdes
2) Desorption Atom
r
6
)
Van der Waals Force
Dispersion Force
EI1 EI2 α1α2 3 1 Edis = − 2 6 2 (4πε0 ) EI1 + EI2 r
same molecule
3 1 EIα Edis = − 4 (4πε0 )2 r6
2
Van der Waals Force
Coalescence of Nuclei
Liquid-like Tr<Tm melting point of film and bulk Thomson-Frankel Model:
2σV Tr = Tm exp(− ) Lr if Tm −Tr = ∆T
Coalescence of Nuclei
Three Basic Growth Modes
Ag on NaCl
Transmission electron microscope images of nucleation, growth, and coalescence of Ag films on (111) NaCl substrates.
STM
Scanning tunneling microscope image of Si deposition on three successive terraces. Field of view is 300 A x 300 A.
STM
Arrhenius plot of island density vs the reciprocal of the substrate temperature.
Experimental Studies of Nucleation and Growth
1 TEM, SEM 2 AES 3 STM, AFM
AES
Schematic Auger signal currents as a function of time for the three growth modes. (a) island, (b) planar, (c) S-K. o = overlayer, s = substrate.
STM
Scanning tunneling microscope images of deposited metal clusters, Ag nuclei on (111) Si
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
Lennard-Jones Equation
E = Ep[( ) − 2( ) ] r r
12 6
rp
rp
Chemisorption
Chemical Bond
Electrovalent Bond Covalent Bond Metal Bond
Chemisorption
Condensation and Diffusion
∆T = Tm[1− exp(−
*
2σ1Vm r =r = kT ln P / P r
2σV )] Lr
2σTmV rL
Tr ∆T σ kT P = ln = 1− Tm σ1L P Tm r
Tm σ kT P = 1+ ln σ1L Tr P r metal
σ kT ≈1 , ≈ 0.1 σ1 L
Process of Thin Films Formation
Phase Transition
Gas, Liquid Atoms, Molecules Solid Films
kT P ∆F = − ln Vm P s
Absorption
Physisorption
Van der Waals Force
1 eV=23.1 kcal/mol =96.5kJ/mol
Physisorption
Van der Waals Force
Attractive Force
E = Ees + Eind + Edis
Repulsive Force
Er = B exp(ar) = Br
−m
Physisorption
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
Molecule He Ar CO Xe CCl HCl HBr HI H2O NH3 Ees 0 0 0.00021 0 0 1.2 0.39 0.021 11.9 5.2 Eind 0 0 0.0037 0 0 0.36 0.28 0.10 0.65 0.63 Edis 0.05 2.9 4.6 18 116 7.8 15 33 2.6 5.6 E(kJ/mol) 0.05 2.9 4.6 18 116 9.4 16 33 15 11
Condensation and Diffusion
Equilibrium
dn n = N ↓= dt τ n =ν nexp(−Qdes 1
τ
kT )
)
1 =ν exp(−Qdes 1
τ
kT
1 exp(Qdes τ=
ν1
kT
)
Condensation and Diffusion
1 Interaction of Adatoms 2 Migration of Adatoms
Ag on NaCl
Transmission electron microscope images of nucleation, growth, and coalescence of Ag films on (111) NaCl substrates.
Au on NaCl
TEM micrographs of Au/NaCl(001) formed at T=250 oC, R=1013 atoms cm-2s-1 and deposition times of (a) 0.5, (b) 1.5, (c) 4, (d) 8, (e) 10, (f) 15, (g) 30 and (h) 85 min.
Repulsive Force
Van der Waals Force
Electrostatic Force
2µ µ 1 Ees = − 2 6 3kT (4πε0 ) r
2 2 1 2
Van der Waals Force
Induced Force
Eind = − 1 (4πε0 )
2
(
α2µ12 +α1µ22
N ↓ enough high, condensation
Condensation and Diffusion
X = 2Ddτ = Dd = a ν exp(−
2
2Dd
ν1
Qdif
Q exp( des )
2kT
)
kT ν Qdes − Qdif X = 2a exp(
ν1
2kT
)
Three Basic Growth Modes
Chemisorption
Chemical Bond
Physisorption Van der Waals Force
Attractive Force
Electrostatic Force (Keesom) Induced Force (Deby) Dispersion Force (London)
Au on NaCl
TEM micrographs of Au/NaCl(001) formed at T=250 oC, R=1013 atoms cm-2s-1 and deposition times of (a) 0.5, (b) 1.5, (c) 4, (d) 8, (e) 10, (f) 15, (g) 30 and (h) 85 min.
AFM
Atomic force microscope images of WXN on SiO2 after (a) 1 s, (b) 2 s, and (c) 3 s. The respective surface rms roughnesses are 0.13 nm (the same as for the original SiO2), 0.50 nm, and 0.48 nm.
AFM
Corresponding Auger spectra
Theories of Nucleation and Films Growth
Section I
Theories of Nucleation and Films Growth
1 Phase Transition 2 Absorption 3 Condensation and Diffusion 4 Three Basic Growth Modes of Thin Films 5 Experimental Studies of Nucleation and Growth
P / P = 102 , Tm / Tr = 1.5 r
Sintering
Successive electron micrographs of Au deposited on MoS2 at 400oC illustrating island coalescence by sintering, (a) Arbitrary zero time, (b) 0.06s, (c) 0.18s, (d) 0.50 s, (e) 1.06 s, (f) 6.18 s
dnd Qdes ∝ exp(− ) dt kT
dnd Qdes = υ1n exp(− ) dt kT
Condensation and Diffusion
Equilibrium
dn = N ↓ dt − n /τ dt = (N ↓ −n /τ )dt n = N ↓τ[1− exp(−t /τ )] when t →∞，n=N ↓τ
Accommodation Coefficient
E0 − Edesorbed T0 − Td αT = = E0 − Esubstrate T0 − Ts
0 ≤ αT ≤ 1
Condensation and Diffusion
1) Desorption Rate
dnd ∝n dt
E>Qdes
2) Desorption Atom
r
6
)
Van der Waals Force
Dispersion Force
EI1 EI2 α1α2 3 1 Edis = − 2 6 2 (4πε0 ) EI1 + EI2 r
same molecule
3 1 EIα Edis = − 4 (4πε0 )2 r6
2
Van der Waals Force
Coalescence of Nuclei
Liquid-like Tr<Tm melting point of film and bulk Thomson-Frankel Model:
2σV Tr = Tm exp(− ) Lr if Tm −Tr = ∆T
Coalescence of Nuclei