|
Single-crystal |
Poly-crystal |
Amorphous Si |
Atomic properties |
Atomic number |
14 |
Electron Shells |
1s22s22p63s23p2 |
|
Radius of Si atom |
1.18 Å |
|
Structure |
Cubic, diamond |
|
Densest planes of Si atoms |
{111} planes |
|
Common Ions |
Si4+, Si4- |
|
Atomic density
(atoms/cm3) |
4.96 x 1022 |
|
Bond angle of adjacent atoms |
109 ° |
|
|
Deviation of bond angles |
|
±10° of ideal crystalline Si bond angle |
Deviation of bond lengths |
|
±2% of ideal crystalline Si bond length |
Density at 300K (g/cm3) |
2.329 |
|
Atomic weight |
28.09 g/g-mol |
Lattice spacing (a0 ) at 300K |
0.54311 nm |
|
Number of atoms in 1 cm3 |
4.995 x 1022 |
|
Distance between two neighboring atoms |
2.35 Å |
|
Atoms per unit cell |
8 |
|
Space Group |
Fd-3m |
|
Heavy hole mass |
0.49 |
|
|
Light hole mass |
0.16 |
|
|
Defect density |
|
|
10-15 cm-1 for a-Si:H-10 at.% |
Longitudinal electron mass (mL) |
0.916 |
|
|
Transverse electron mass (mL) |
0.19 |
|
|
Radiative recombination coefficient (cm3s−1) |
1.1 × 10−14 |
|
|
Mechanical properties |
Piezoresistive coefficient |
n-Si: p11 = -102
p-Si: p44 = +138
Gauge factor of 90 |
Gauge factor of 30 - 50 |
|
Fracture strength (GPa) |
6 |
0.8 to 2.84 (undoped) |
|
Residual stress
|
None |
Depending on structure; compressive |
|
Poisson ratio
|
0.262 maximum for (111) |
0.23 |
|
Young's modulus (N/m2) |
1.90 x 1011 for (111) |
1.61 x 1011 |
|
Elastic constant (dyn cm-2) |
C11=16.6 ×10−11 at 300 K; C12=6.4 ×10−11 at 300 K; C44=7.96 ×10−11 at 300 K |
|
|
Thermal properties |
Thermal conductivity (W/cm-°C) |
1.5-1.57 |
Smaller for poly-Si films with fine grains and much greater with large grains |
|
Thermal expansion (/°C)
|
2.3 |
2-2.7 |
|
Specific heat (cal/g-°C) |
0.169 |
|
Boiling point |
2480 °C |
|
|
Melting temperature |
1412 °C |
|
|
Melt heat (Qm, J-g-1) |
337 |
Critical temperature |
4920 °C |
|
|
Vapor pressure (Pa) |
1 at 1,650 °C; 10-6 at 900 °C |
|
|
Vaporization temperature (Tv, °C) |
2355 |
Vaporization heat (Qv, J-g-1) |
1446 |
Critical pressure (atm) |
1450 |
|
|
Coefficient of thermal expansion (CTE) (°C-1) |
(2.6 - 4.68)
x 10-6 for average between 15-1000 °C; 4.2 x 10-6 at 25 °C; zero at -157 °C; negative at liquid air temperature |
|
|
Thermal diffusion coefficient (cm2/s)
|
0.9 |
|
|
Entropy at 298 °K |
4.5 cal/mol/°K |
|
|
Diffusion length |
|
|
300 nm for a-Si:H-10 at.% |
Hole diffusion length |
|
|
1 µm for a-Si:H-10 at.% |
Optical properties |
Refractive index |
3.42 - 3.44 |
4.05 at 500 nm;
4.1 at 600 nm; 3.93 after deposition at T < 580 °C; 3.51 after deposition at T > 600 °C |
|
Cathodoluminescence (minimum voltage for excitation) |
2400 |
|
1600 |
Photoluminescence peak |
|
|
1.25 eV for a-Si:H(F)-10 at.% at 77 K |
Color |
Dark, steel gray for single crystal; Black, six-sided plates for graphitoidal Si; |
Transparent or light orange for small crystal (similar to c-Si film); |
Dark brown |
Absorption coefficient
(cm-1)
|
|
5.82 x 106 at 3.5 eV |
|
Pre-exponent conductivity factor (Ω-1-cm-1) |
|
|
>103 for a-Si:H(F)-10 at.% |
Indirect energy gap/Optical band gap Eg (eV) |
1.12 at 300 K; 1.17 at 0 K (Minimum indirect Eg) |
1.6 at 210 °C; 2.0 at 350 °C. |
1.55 for a-Si;
1.68 for a-Si:H,F;
1.7 - 1.8 for a-Si:H-10 at.% at 300 K |
Direct energy gap (Γ, eV) |
3.5 |
|
|
Variation of optical band gap with temperature
(eV-K-1) |
|
|
2x - 4x 10-4 |
ESR spin density (cm-3) |
|
|
1015 for a-Si:H(F)-10 at.% |
Spin–orbit splitting (eV) |
0.044 |
|
|
Infra-red spectra |
|
|
2000/640 cm-1 for a-Si:H(F)-10 at.% |
Optical phonon energy (meV) |
64 |
|
|
Electrical properties |
Conduction band tail slope (meV) |
|
|
25 for a-Si:H(F)-10 at.%; 30 for a-Si |
Conduction band minimum |
X |
|
|
Valence band tail slope (meV) |
|
|
40 for a-Si:H(F)-10 at.%; 50 for a-Si |
Activation energy (ΔE) |
|
≤0.05
for n-type a-Si:H ~1% addition of PH3 to gas phase; ≤0.05 for p-type a-Si:H ~1% addition of B2H6 to gas phase |
0.8 - 0.9 for a-Si:H(F)-10 at.%; 0.2 for n-type a-Si:H ~1% addition of PH3 to gas phase; 0.3 for p-type a-Si:H ~1% addition of B2H6 to gas phase |
Urbach energy E0 (meV)
|
|
|
46 for a-Si:H; 48 for a-Si:H,F |
Electron affinity |
4.05 eV |
|
|
Density of states
in band gap (cm-3) |
|
|
1 x 1019 for a-Si; 1 x 1016 for a-Si:H |
Density of states at the minimum (cm-3eV-1) |
|
|
>1015 – 1017 for a-Si:H(F)-10 at.% |
Fermi level density of states g (EF) (cm-3eV-1)
|
|
|
1015 for a-Si:H; 1015 for a-Si:H,F |
Effective density of states at the conduction band edge
(Nc, cm-3eV-1) |
2.8 x 1019 at 300 K |
|
1021 for a-Si:H(F)-10 at.% |
Effective density of states at the valence band edge
(Nv, cm-3eV-1) |
1.04 x 1019at 300 K |
|
|
Extended state mobility: electron (cm2s-1V-1)
|
|
|
>10 for a-Si:H(F)-10 at.% |
Extended state mobility: hole (cm2s-1V-1) |
|
|
~1 for a-Si:H(F)-10 at.% |
Hole drift
mobility µh
(cm2V-1s-1) |
450-600 |
|
10-20
for a-Si:H; 10-2 for a-Si:H(F)-10 at.% |
Electron drift
mobility µe
(cm2V-1s-1) |
≤1500 |
20 - 40 |
1 for a-Si:H-10 at.% |
Intrinsic carrier concentration ni |
1.0 x 1010 cm-3 |
|
|
Minority carrier lifetime |
2.5 x 10-3 s |
8 x 10-11 for grain size 0.2 µm; 7 x 10-6 for grain size 4,000 µm |
|
Intrinsic Debye length |
24 µm |
|
|
Dielectric Constant at 300 K |
11.9 |
|
|
Temperature resistivity coefficient (TCR, °C-1)
|
p-type: 0.0017 |
Nonlinear; e.g. 0.0012; between negative and positive depending on doping level |
|
Dark conductivity (Ω-1-cm-1)
|
|
≥1 for n-type a-Si:H: ~1% addition of PH3 to gas phase; ≥1 for p-type a-Si:H: ~1% addition of B2H6 to gas phase |
10-10 for a-Si:H(F)-10 at.% at 300 K; 10-2 for n-type a-Si:H: ~1% addition of PH3 to gas phase; 10-3 for p-type a-Si:H: ~1% addition of B2H6 to gas phase |
Electrical resistivity (Ω-cm) |
Depending on doping level at room temperature; 2 x 103 at -190°C; (2.3 - 3.2) x 105 at 22 °C; 15 at 300 °C; 0.4 at 500 °C |
Strong function of the grain structure of the film; always higher than that of Si single crystals; 4 x 105 for doping level <1015 cm-3;
|
1011 for undoped a-Si:H-10 at.% at 300 K; 102 for n+ a-Si:H-10 at.% at 300 K;
103 for p+ a-Si:H-10 at.% at 300 K |
Breakdown field |
3 x 105 V/cm |
|
|
Electron diffusion constant |
34.6 cm2s-1 |
|
|
Hole diffusion constant |
12.3 cm2s-1 |
|
|