3.2.1 Mass Density

The values for the mass density are given in Table 3.2. For Al$_{2}$O$_3$, two values are given, one for sapphire, which is the substrate material for GaN devices, one for alumina, which is used as packaging material.

Table 3.2: Mass density parameters for semiconductors and insulators.

Material	$\rho$ [g/cm$^3$]	Reported Range	References
GaAs	5.32	5.3165	[4,194]
AlAs	3.729	3.76	[4]
InAs	5.67	5.70	[52,294]
InP	4.791	4.81	[3,85]
In$_{0.52}$Al$_{0.48}$As	4.90	-	[163]
Al$_{0.51}$Ga$_{0.49}$As	4.50	-	-
GaN	6.087	6.15	[89]
AlN	3.23	3.23	[89]
InN	6.810	6.81	[89]
Si	2.33	2.328	[194]
Si$_3$N$_4$	3.1	-	[194]
SiO$_2$	2.20	2.27	[194,284]
Al$_{2}$O$_3$ (sapphire)	3.98	-	[173]
Al$_{2}$O$_3$ (alumina)	3.9	3.89	[173]
BCB	0.95	0.93-0.99	[61]
SiC 6H	3.21	3.210-3.248	[114]
BeO	2.85	-	[173]
Diamond	3.515	-	[73]

For the ternary compounds the mass density is composed as from the binary constituents, and for the quaternary materials the ternary constituents are considered pseudobinary materials from their ternary compounds, respectively, as given in (3.19).

$$\rho_{AB} =  x \cdot \rho_{A} + (1-x) \cdot \rho_{B}$$ (3.19)