High temperature behavior of ceramic substrates for power electronics applications

Aluminium oxide (Al₂O₃), Aluminium Nitride (AlN) and Silicon Nitride (Si₃N₄) are ceramics commonly used in power electronics modules, and are the current candidates for high temperature applications. A first study has previously shown different charge displacement behaviors at high temperature (up to 400°C). Surface potential measurements revealed a fast decay for AlN and Al₂O₃ with the increase of the temperature while on Si₃N₄ charges remain on surface at 400°C. However, these charges may move through the surface or be injected in the volume of the ceramics. - Surface potential results are correlated with broadband impedance spectroscopy and to current-voltage measurements of the ceramics. AlN and Al₂O₃ have a resistive-like behavior at high temperature, characterized by a space charge limited conduction current mechanism at high fields. For Si₃N₄, despite its resistivity decreases with temperature, it shows a dielectric behavior and an ohmic conduction mechanism over the studied temperature and field ranges.