SiC (silicon carbide) properties: e.g. 6H-, 4H- and 3C-(β-)SiC

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SiC (Silicon Carbide) Properties: e.g. 6H-, 4H- and 3C-(β-)SiC

Silicon carbide (SiC) has a critical breakdown field that is an order of magnitude higher than that of silicon (Si), along with a bandgap and thermal conductivity approximately three times greater. These properties collectively enable SiC to offer roughly three times the cooling efficiency.

Among the various polytypes of SiC (silicon carbide) structures, 6H-SiC and 4H-SiC are the most commonly used, particularly for device manufacturing, due to their ability to form large wafers and their commercial availability. For high-power, high-temperature, and high-frequency device applications, 4H-SiC is the preferred and widely used material because of its superior electron mobility, [1, 2] wider bandgap, higher critical electric field, [3] and lower ionization energy of dopants, [4] as well as the availability of single crystalline wafers. Additionally, unlike 6H-SiC, [5] 4H-SiC does not exhibit anisotropic electron mobility, which has contributed to its focused development and broader availability.

Table 1524a. Comparison of the key properties of Silicon (Si), Silicon Carbide (SiC), and Gallium Nitride (GaN).

Material	Critical Electric Field (E_CR)	Electron Mobility	Hole Mobility	Thermal Conductivity (k)	Bandgap (E_g)	Intrinsic Carrier Concentration (n_i)	Maximum Junction Temperature (T_j)
Silicon (Si)	0.3 MV/cm	1400 cm²/Vs	600 cm²/Vs	1.5 W/cm·K	1.1 eV	1.5 × 10¹⁰ cm^-3	~150°C
Silicon Carbide (SiC)	2.8 MV/cm	900 cm²/Vs	100 cm²/Vs	4.9 W/cm·K	3.26 eV	10 cm^-3	~300°C
Gallium Nitride (GaN)	3.3 MV/cm	1250 cm²/Vs	200 cm²/Vs	1.3 W/cm·K	3.4 eV	1 cm^-3	~400°C

Table 1524a. Comparison of material parameters of polytypes of SiC and Si.

Material Parameter	4H-SiC	6H-SiC	3C-SiC	Si
Energy Bandgap at 300 K (eV)	3.26	3.03	2.3	1.12
Lattice Constant at 300 K (Å)	3.076	3.081	4.349	3.84
Critical Electric Field (V/cm)	2.2 × 10⁶	2.5 × 10⁶	2 × 10⁶	2.5 × 10⁵
Saturated Electron Drift Velocity (cm/s)	2 × 10⁷	2 × 10⁷	2.5 × 10⁷	1.0 × 10⁷
Thermal Conductivity (W/cm^-1K^-1)	3.0–3.8	3.0–3.8	3–4	1.5
Intrinsic Carrier Concentration (cm^-3)	10^-7	10^-5	10	10¹⁰
Electron Mobility at N_D = 10¹⁶ (cm²/V-s)	900	60	750	1400

[1] Palmour, J.; Singh, R.; Glass, R.; Kordina, O.; Carter, C. Silicon carbide for power devices. In Proceedings of the 9th International Symposium on Power Semiconductor Devices and IC’s, Weimar, Germany, 26–29 May 1997; pp. 25–32.
[2] Itoh, A.; Akita, H.; Kimoto, T.; Matsunami, H. High-quality 4H-SiC homoepitaxial layers grown by step-controlled epitaxy. Appl. Phys. Lett. 1994, 65, 1400–1402.
[3] Konstantinov, A.;Wahab, Q.; Nordell, N.; Lindefelt, U. Ionization rates and critical fields in 4H silicon carbide. Appl. Phys. Lett. 1997, 71, 90–92.
[4] Wijesundara, M.; Azevedo, R. Silicon Carbide Microsystems for Harsh Environments; Springer Science & Business Media: Berlin/Heidelberg, Germany, 2011; Volume 22.
[5] Neudeck, P.G. Silicon Carbide Technology. The VLSI Handbook, 20061800. 2006.

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SiC (Silicon Carbide) Properties: e.g. 6H-, 4H- and 3C-(β-)SiC