Twist's Review #6 - High Breakdown Voltage Lateral Diamond Diode

Paper: Diamond p-Type Lateral Schottky Barrier Diodes
With High Breakdown Voltage (4612 V at
0.01 mA/Mm)

Diamond has attracted attention as a semiconductor, specifically a wide bandgap semiconductor, for its potential in power electronics due to its large bandgap, large breakdown electric field, high carrier mobility and thermal conductivity. Despite the amount of time invested into research of diamond-based electronic devices, it is still quite difficult to commercialize such a device as further studies are needed in regards to the device structure, and process.

This paper published by a group in UIUC, USA, shows a lateral dimond schottky barrier diode with a high breakdown voltage of 4612 V and leakage current of 0.01 mA/mm. This was achieved by adding field plates made of Al2O3. A device with no field plates was also fabricated and showed a breadown voltage of 1159 V. The ohmic and schottky contact stack was made of Ti (30nm) / Pt (30nm) / Au (100nm) and Mo (50nm) / Pt (50nm) / Au (100nm) respectively. The ohmic contact had resistance of about 1.25e-4 ohm-cm2.

Unfortunately, despite the low it showed higher Ron compared to previous reports. The author hopes for further study and optimization for the device’s drift layer thickness and doping concentration to minimize the Ron even further.

Reference:
[1] Z. Han and C. Bayram, “Diamond p-Type Lateral Schottky Barrier Diodes With High Breakdown Voltage (4612 V at 0.01 mA/Mm),” in IEEE Electron Device Letters, vol. 44, no. 10, pp. 1692-1695, Oct. 2023, doi: 10.1109/LED.2023.3310910.

I learnt wide bandgap semiconductors for a while and diamond was an interesting material for this application, because while it does make sense I always thought it would be hard to optimize the devices based on diamond. Field plates is not something new, it was also implemented in GaN HEMTs, albeit I hae seen other materials in use as the dielectric material, so it was interesting to see Al2O3 used here. I think it would be intriguing to see other dielectric like HfO2, which I think has a higher dielectric constant than Al2O3, used for the field plates here.

Also, as you have noticed, this review is very late. I had some errands to do around December and early this month so I postponed all thos reviews and I will be making them soon. Expect some other reviews quite soon.