The elastic constants of silicon carbide: A Brillouin-scattering study of 4H and 6H SiC single crystals

Abstract

The complete sets of elastic constants of 4H and 6H silicon carbide single crystals were determined by Brillouin scattering. The elastic constants of 6H SiC are C11=501±4, C33=553±4, C44=163±4, C12=111±5, and C13=52±9 GPa; the corresponding ones of 4H SiC are the same within experimental uncertainties. The compressibility, 4.5×10−3 GPa, is about 3–5 times smaller than those reported for polycrystalline SiC materials.

Experimental Characterization of the Thermal Time Constants of GaN HEMTs Via Micro-Raman Thermometry

“…The values of 300 = 170 W/m-K and = 1.44 for GaN [30]- [31] and 300, = 490 W/m-K, 300, = 390 W/m-K, and = 1.49 for 4H-SiC [32]- [33] were taken from the literature. The mass density ( = 6087 kg/m 3 [34], = 3220 kg/m 3 [35]) and specific heat values with their temperature dependencies were also taken from the literature [36]- [37]. The thermal boundary resistance (TBR) at the GaNSiC interface associated with the AlN nucleation layer was set to a constant value of 5 m 2 -K/GW, in agreement with recently reported values measured by time-domain thermal reflectance (TDTR) [30]- [31].…”

“…The elastic constants for GaN, 4H-SiC, and indium were taken from [34]- [35], [38] and the temperaturedependent coefficients of thermal expansion for GaN and 4H-SiC were taken from [4], [39]. The bottom of the indium solder die-attach was set to zero displacement, and all other surfaces, including the top of the GaN buffer, were set to free boundaries (zero stress).…”

Thermoelastic stresses in SiC single crystals grown by the physical vapor transport method

“…(3) and there are only five independent elastic constants. Since there are no experimental data with respect to elastic constants of SiC single crystal at high temperatures available, elastic constants at room temperature are used in our calculation, c 11 = 501 ± 4 GPa, c 33 = 553 ± 4 GPa, c 44 = 163 ± 4 GPa, c 12 = 111 ± 5 GPa, c 13 = 52 ± 9 GPa [11]. It is necessary to measure the elastic constants of SiC at high temperatures in future.…”

Dynamic compressibility, shear strength, and fracture behavior of ceramic microstructures predicted from mesoscale models

“…Properties for SiC and AlON single crystals are listed in Table 1 [11][12][13][14][15]. A cohesive zone model addresses intergranular fracture, i.e., stress-induced separation between grains in a given polycrystal [14,[16][17][18][19][20].…”