Revolutionizing Electronics: The Power of Aluminum Nitride
As governments worldwide promote renewable energy sources, effective power electronics are of vital importance. Cornell engineers in collaboration with Florida-based technology company Lit Thinking are harnessing AlN’s potential to address this pressing need.
This project’s objective is to develop AlN pin diodes with extremely low on-state electrical resistance in order to minimize power loss and heat generation while significantly increasing device efficiency.
1. High Thermal Conductivity
Aluminum nitride boasts an outstanding thermal conductivity of 180 W/mdegK, making it an excellent material for electrical engineering applications. Furthermore, due to its excellent electrical insulating properties and thermal conductivity properties, aluminium nitride often serves as the substrate material in semiconductor and high-power electronic component manufacturing processes.
Aluminium nitride’s excellent machinability allows it to be machined into complex geometries before being sintered and densified – giving rise to hard surfaces that rival those found in beryllia and alumina ceramics, yet non-toxic enough for use as technical ceramics and non-toxic potting compounds.
Aluminum nitride (AlN) is one of the three III-nitrides, a group of semiconductor materials which also include gallium nitride (GaN) and indium nitride (InN). These wide band gap semiconductors have become key elements of modern optoelectronics and electronic devices, providing significantly greater mechanical stiffness compared to silicon crystal semiconductors as well as greater optical transparency, optical insulation properties, electrical isolation capabilities that make III-nitride semiconductors attractive candidates for producing n-channel and p-channel HEMTs.
2. High Electrical Resistivity
Aluminum nitride provides excellent electrical insulation, featuring low dielectric constant and large band gap at room temperature, making it an excellent material for high speed and power electronics.
Aluminium nitride in its pure state possesses a thermal conductivity of around 180W/mK, similar to beryllium oxide but higher than silicon carbide (SiC). However, this thermal conductivity can be enhanced significantly through adding nitrogen gas during fabrication processes.
Aluminium nitride is an outstanding insulator with superior mechanical strength and resistance to plasma erosion, making it suitable for many industrial uses like ceramic substrates, semiconductor wafer supports and evaporation boats.
At lower temperatures, aluminium nitride has even greater electrical properties than beryllium oxide and is considered one of the top group III nitrides for insulation properties.
3. Piezoelectric Properties
Aluminum nitride exhibits both direct and indirect piezoelectric properties. When subjected to force, aluminum nitride generates voltage which can be harnessed for actuators such as high-speed atomic force microscopy and nanoscale electromechanical switches (resonators also take advantage of this effect). Conversely, deformation caused by electric fields may induce currents within it that can be utilized as sensors.
Aluminum Nitride’s hexagonal structure allows it to be deposited as a thin film via physical vapor deposition processes such as reactive sputtering. This produces films with excellent composition control on their c axis out-of-plane orientations; an ideal choice for piezoelectric MEMS applications as it poses lower contamination risks than lead zirconium titanate but works at higher temperatures than zinc oxide.
PFM measurement makes it possible to directly extract the piezoelectric coefficient d33 from AlN samples using PFM measurement, using its converse piezoelectric effect where an excitation voltage causes deformation that can then be detected by the probe. The method is straightforward and reliable, yielding theoretically rational d33 values.
4. Thermal Shock Resistance
Aluminum nitride (ALN) is a solid material with a hexagonal crystal structure, covalently bound through hot pressing and the use of sintering aids, that requires hot pressing to produce dense technical grade material. While it remains stable at temperatures below 700degC it will oxidize at temperatures over this threshold, producing 5-10nm thick oxide films that protect it until temperatures of 1370degC when bulk oxidation begins. However it remains stable in hydrogen/carbon dioxide up to 980degC but slowly hydrolyzes in water environments if left long enough.
AIN is nontoxic and features superior chemical corrosion resistance as well as thermal expansion properties similar to silicon, making it the ideal material for large-scale integrated circuit heat dissipation substrates, LED packages, power modules and electrostatic chucks for wafer processing. Furthermore, its electrical conductivity and insulating properties combine for excellent use in this application.
5. Mechanical Strength
Aluminum nitride boasts superior mechanical strength, thermal shock resistance and fatigue resistance while remaining relatively brittle over time. Mohs hardness of 9 makes aluminum nitride perfect for power electronics and microelectronic applications due to its 14 Weibull modulus and crack growth susceptibility parameter of 12. This makes aluminum nitride an excellent material choice in these fields.
Aluminum nitride is a non-toxic alternative to beryllium oxide and more durable than tungsten carbide. Aluminum nitride typically forms aluminium-rich wurtzite crystal structures; however, metastable cubic zincblende phases may also form.
This material offers great corrosion resistance to molten aluminum, gallium arsenide and various other metals; however it lacks high-temperature oxidation resistance, is susceptible to moisture absorption from airflow and hydrolysis.
Machinable AlN is unique among ceramics in that it can be formed into complex shapes during its full density state, offering greater versatility than its green and biscuit forms. As such, machinable AlN can be utilized in electronic devices similar to silicon carbide ceramics, including Shapal Hi M Soft which combines high electrical insulation, thermal conductivity, and mechanical strength with excellent electrical resistance and mechanical strength properties.