Breakthrough in diamond p-type lateral SBDs
The $200 billion semiconductor industry derives 10 percent of its revenue from power semiconductor devices and ICs. Over 50 percent of the world’s electricity is thought to be controlled by power devices. Boosted by the emergence of renewable power sources, this number is projected to increase to 80 percent by 2030.
The US Energy Information Administration projects that the worldwide energy demand for electricity will increase nearly 50 percent by 2050; making i critically important to utilise emerging ultrawide bandgap materials to realise fast, power efficient, robust, and reliable semiconductor switches to eliminate 90 percent of the power loss in electricity conversion.
As the material of choice, diamond is central to all these needs as it has the highest thermal conductivity, is the hardest semiconductor known with a high breakdown field and high saturation velocity combined with a lowest thermal expansion coefficient. With its ultra-wide bandgap of 5.47 eV, breakdown field strength of ∼10 MV/cm, and thermal conductivity of ∼2,200 W/mK, diamond surpasses the performance of its wide (GaN) and ultra-wide (Ga2O3, AlN) bandgap semiconductor counterparts.
In IEEE Electron Device Letters, the University of Illinois team reports diamond Schottky barrier diodes (SBDs) with record breakdown voltage (4612 V). This demonstration is thanks to the innovative lateral architecture with highly conductive contact regrowth approach and field-plate edge termination technique. Al2O3 field plates mitigate the electric field crowding near the edge of the contacts and improve reverse bias performance. The SBD with the Al2O3 field plate exhibit leakage current density lower than 0.01 mA/mm under a reverse bias of 4.6 kV, marking one of the highest breakdown voltages ever reported by diamond SBDs. This is also the first report of lateral diamond SBDs with field-plate edge termination technique.
Pictured above: (Left) Schematic and microscope image of the diode (from top to bottom) Cross-sectional sketch of the diode, and top view image of a fabricated diode with the field plate. (Right) Benchmark of the fabricated lateral Schottky diodes compared with previously reported diamond power devices including lateral MESFETs, MOSFETs and junction FETs, and pseudo-vertical and vertical Schottky diodes at room temperature. The leakage currents at which the breakdown is reported are shown in the brackets.
Reference
'Diamond p-type lateral Schottky barrier diodes with high breakdown voltage (4612 V at 0.01 mA/mm)' by Z. Han, and C. Bayram; IEEE Electron Device Letters (2023)
