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Cadmium Oxide

Crystal: CdO

Structure: NaCl

Usually nonstoichiometric with Cd in excess: n-type deg. semiconductor; see Refs.1-3

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Mechanical and structural properties:

Cohesive energy:	eV
Lattice parameter:	Å
Energy:	g/cm³

Stiffness constants: in 10¹¹ dynes/cm², at room temperature

c₁₁:

c₁₂:

c₄₄:

Compressibility (in 10¹¹ dynes/cm²): 1.32*10¹² (Ref.4) ?? Also: 0.88*10¹² (Ref.5) ??

Poisson ratio:

Debye temperature: 279 K

Melting temperature: ° C

Phonon spectrum discussed by:

Transverse optic phonon T0 (k=0): 262±3 cm^-1

Longitude optic phonon L0 (k=0): 478±25 cm^-1

Plasma frequency: ~2400 cm^-1 (this low energy must correspond to some specific carrier density; the bulk plasmon will be much higher)

Gruneissen constant:

Ratio e*/e:

Photoelastic constants:

p₁₁:

p₁₂:

p₄₄:

Electronic properties:

Band gap:

direct: 2.28 eV. at 100 ° K. for G 1, G 15 (Ref.6)

indirect: 0.84 eV. at 100K. for G 1-S 3 (Ref.6), 1.09 eV. at 100K. for G 1-L3 (Ref.6)

Gap: eV.

First exciton: eV.

Plasmon (eV.): 22.8 (bulk) (Ref.7), 15.9 (surface)

Band structure :

UV reflectance data:

J.L. Freeouf, Far Ultraviolet reflectance of II-IV compounds and correlation with the Penn-Philips Gap, Phys. Rev. B7, 3810 (1973)

Self cons. band structure:

J.C. Boettger, A.B. Kunz, Ab initio energy bands for CdO, Phys. Rev. B27, 1359 (1983)

Static dielectric constant: 18.1±2.5

Optic dielectric constant: 5.4

m = 2.49 (Winchell & Winchell)

e (¥ )= 6.2

Electron mobility:

Hole mobility:

Polaron coupling constant: a = ~1.02 ( for m*=1 )

Effective mass: conduction band:

valence band:

Electron affinity: ( in eV., from bottom of conduction band under vacuum)

Spin-orbit coupling: ( valence band)

Cation polarisation: Å^-3

Anion polarisation: Å^-3

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Other information:

E. Rantavuori et al. give:

CdO: x-ray analysis of ionicity:

Radii: Cd 1.24±0.05 Å O 1.25±0.05 Å

Charge: Cd (+1.7±0.2)½ e½

Ref.: E. Rantavuori, M. Linkoaho and R. Kuoppala, The ionicity of CdO by x-ray powder diffraction at 80K, Phys. Scripta 16, 161 (1977)

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References:

1. H. Finkenrath, W. Waidelich, Der Einfluss der Gitterschwingungen auf die Ultrarot-Reflexion von CdO, Sol. St. Comm. 5, 875 (1967)

2. Sol. St.Comm. 7, 11 (1969)

3. K.H. Rieder, M. Ishigarne and L. Genzei, Infrared absorption by coupled surface-phonon-surface-plasmon modes in microcrystals of CdO, Phys. Rev. B6, 3804 (1972)

4. Parodi

5. Lewiz, Perey (1966)

6. F. Koffyberg Thermoreflectance spectra of CdO: Band gaps and band population effects, Phys .Rev. B13, 4470 (1976)

7. R.L. Hengehold, F.L. Pedrotti, Plasmon excitation energies in ZnO, CdO, MgO, J. Appl. Phys. 47, 287 (1976)

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