TCAD Investigation of Differently-Doped DLC Passivation for Large-Area High-Power Diodes

An electroactive passivation for high-voltage diodes with bevel termination has been investigated based on diamond-like carbon (DLC) films. Variations of the DLC properties, i.e., conductivity and geometry, have been investigated by experiments and numerical simulations to the purpose of gaining an insight on their influence on the diode leakage current and breakdown voltage. The role played by the DLC/Si interface has been investigated by characterizing metal-DLC-Si devices. Both Boron and Nitrogen doping have been investigated and a TCAD setup has been provided accounting for the main transport features of the DLC material with different doping configurations. A significant polarization effect has been observed in the DLC material, which improves the DLC performance as a passivation material. High-voltage diodes have been characterized and simulated with different DLC layers on top of the bevel termination in order to identify the role played by conductivity and polarization on the blocking state. The correlation of leakage current and voltage breakdown with the DLC doping and thickness is provided and explained by the TCAD simulation results.