AlN (aluminum nitride) has lower losses and higher voltage withstand than SiC (silicon carbide) and GaN (gallium nitride).DiskMFR Marketing Department from YUNZE
Recently, a Japanese company (NTT) said they have successfully achieved transistor operation using AlN (aluminum nitride), which puts AIN on track to become the next generation of power semiconductor materials beyond SiC (silicon carbide) and GaN (gallium nitride.) AlN, along with gallium oxide and diamond, is known as an ultra-wide bandgap semiconductor and is said to be the first in the world to successfully achieve the transistor needed to use it as a power semiconductor. operation.
In terms of physical properties, AIN has lower losses and higher withstand voltage than silicon carbide (SiC) and gallium nitride (GaN), and therefore can form high-voltage and efficient power circuits. This is very large compared to the 1.1eV of silicon (Si), 3.26eV of SiC, and 3.4eV of GaN. Therefore, it is counted as one of the “ultra-wide bandgap semiconductors” along with diamond semiconductors.
Due to the large bandgap, the dielectric breakdown electric field strength is also high. If power devices can be fabricated, the power loss can theoretically be reduced to less than half of that of SiC or GaN.
High-quality AlN semiconductor transistors have an increasing trend of voltage source and current source characteristics and very small leakage currents due to ohmic characteristics. In addition, the regulated voltage value as a power semiconductor reaches 1.7kv.
It is also clear that AlN transistors can operate stably even at high temperatures. Unlike conventional semiconductor materials, the performance of AlN transistors is improved at high temperatures, and the current increases by about 100 times at 500°C. In addition, the leakage current can be suppressed to a very low level of 10-8A/mm even at 500°C.
There are three technical points that led to this achievement. The first is the high-quality AlN manufacturing technology. By developing a unique MOCVD technology, a raw material gas supply method was designed so that AlN crystals can be manufactured at high temperatures, and the residual impurities and crystals in AlN crystals were developed to reduce the defect density. Finally, a high-quality n-type conducting AlN semiconductor with the world’s highest electron mobility was achieved.
Second, the electrode formation technology with good ohmic properties. Since AlN has a large energy potential barrier with the metal material used as the electrode, it is difficult to form ohmic contacts. Therefore, good ohmic characteristics were successfully obtained by forming a tilted AlGaN layer with gradually reduced Al composition on AlN and by bringing AlGaN with low Al composition, which is easy to form ohmic contacts, into contact with the metal.
Third, the ideal shortcut bonding characteristics are achieved. Schottky characteristics are influenced by the crystalline quality of the semiconductor, the metal-semiconductor interface, and the contact resistance on the ohmic electrode side, in addition to the type of metal material. As mentioned above, NTT achieves high-quality AlN and good ohmic contact, resulting in Schottky characteristics with a good rectification effect.