The reliability of Ni contacts to n-SiC subjected to pulsed thermal fatigue

Laboratory experiments which mimic the acute cyclic thermal loading characteristic of pulsed power device switching operation have been developed. Ni contacts to n-SiC were the device components selected for cyclic thermal testing. Modifications of the contact-SiC materials properties in response to cyclic thermal fatigue were quantitatively assessed via Rutherford backscattering spectrometry, nanoindentation testing, and current-voltage measurements. Decreases in nanohardness and elastic modulus were observed in response to thermal fatigue. No compositional modifications were observed at the metal- semiconductor interface. Our results demonstrated that the majority of the material changes were initiated after the first thermal pulse and that the effects of subsequent thermal cycling (up to 10 pulses) were negligible. The stability of the metal- semiconductor interface after exposure to repeated pulsed thermal cycling lends support for the utilization of Ni as a contact metallization for pulsed power switching applications. (C) 1999 The Electrochemical Society. S1099- 0062( 98) 09- 049- X. All rights reserved.