Advantages of Aluminum Nitride Cte As a Buffer Layer for HEMTs

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aluminum nitride cte (AlN) is an aluminum nitride based material that has recently received significant interest due to its superior performance as a buffer layer for nitride-based high electron mobility transistors (HEMTs). As compared to oxides like Al2O3, AlN has better thermal management properties which lead to reduced buffer leakage, allowing the integration of n-channel and p-channel devices on the same device.

The material has been characterized with high thermal conductivity up to 260 W/(m*K) and electrical insulation properties that are comparable with beryllia oxide (BeO). In addition, it is non-toxic, which eliminates the need to handle toxic and hazardous vapors when grinding or machining. Its low coefficient of thermal expansion is also an attractive feature.

The insulating and conductivity characteristics of the material are partly explained by its structure. It is a polycrystalline material exhibiting the low-temperature wurtzite crystal structure with lattice constants c and a and atomic arrangement in the form of interpenetrating, closest packed metal and nitrogen atoms in the AB4 tetrahedra. The wurtzite crystal structure is stable at low temperatures and can be converted to the metastable cubic zincblende phase at elevated temperature by applying external pressure.

The material is well-suited for a wide variety of applications. It has a high oxidation resistance, chemical resistance and mechanical strength. It is also corrosion-resistant to many molten metals and gases. In addition, it has a very low dielectric constant and thermal expansion coefficient close to that of silicon.