Germanium (Ge) is a key material in semiconductor manufacturing. Due to its high electron mobility, it's crucial for high-speed electronic devices. Its direct bandgap in thin layers makes a germanium wafer useful for optoelectrical applications.
Nevertheless, like any material, germanium comes with some limitations. Its thermal properties can be disadvantageous for device performance, particularly under high-temperature conditions. To help you understand why, let's look at the key factors about germanium’s thermal conductivity that you need to know.
At room temperature (300 K), germanium's thermal conductivity is about 60 watts per meter-kelvin (W/m·K), which represents its heat conductivity.
Germanium transfers heat less effectively than silicon, which has a thermal conductivity of roughly 150 W/m·K. This could be an issue in high-power or high-frequency applications, where efficient heat dissipation is essential.
At room temperature, germanium has a coefficient of thermal expansion of about 5.8 × 10⁶ per Kelvin (1/K). In other words, a germanium wafer will expand by a tiny, predictable amount for every degree of temperature expansion.
This is crucial for controlling thermal stresses and is comparatively mild, particularly when germanium is bonded to other materials that expand at different rates.
The melting point of germanium is 938.3°C (1711°F). Compared to the melting point of silicon, which is 1414°C, this is much lower.
The lower melting point can affect the thermal stability of germanium-based devices during fabrication and sets a maximum processing temperature limit.
At room temperature, germanium has a specific heat capacity of roughly 0.32 joules per gram-kelvin (J/g·K). This property indicates the amount of energy required per gram of material to raise the temperature of germanium by one degree.
A lower value indicates that, given the same energy input, germanium heats up more quickly than some other materials.
Germanium has a Debye temperature of approximately 374 K. This parameter is related to the vibrational properties of the crystal lattice. It affects how heat is stored and transported within the material, especially at low temperatures.
The thermal diffusivity of germanium, which gauges the rate at which heat moves through a substance, is approximately 0.36 cm²/s. It is derived from density, specific heat capacity, and thermal conductivity and contributes to transient heat transfer in applications like fast electronic switching and pulsed lasers.
As you can see, germanium wafers exhibit a number of important thermal characteristics that influence their performance in electronic and optical applications. Ge's lower thermal conductivity than Si must be compensated for in high-frequency electronics, where thermal management is critical.
In infrared optics, germanium’s thermal expansion and stability influence precision optical applications. That doesn’t mean that this material can’t be used. If you need help figuring out whether germanium wafers are the right choice for your project, contact Wafer World!
