US Patent 9214352 Ohmic contact to semiconductor device

Embodiments of an ohmic contact structure for a Group III nitride semiconductor device and methods of fabrication thereof are disclosed. In one embodiment, the ohmic contact structure has less than or equal to 5%, more preferably less than or equal to 2%, more preferably less than or equal to 1.5%, and even more preferably less than or equal to 1% degradation for 1000 hours High Temperature Soak (HTS) at 300 degrees Celsius. In another embodiment, the ohmic contact structure additionally or alternatively has less than or equal to 10% degradation, more preferably less than or equal to 7.5% degradation, more preferably less than or equal to 6% degradation, more preferably less than or equal to 5% degradation, and even more preferably less than 3% degradation for 1000 hours High Temperature operating Life (HToL) at 225 degrees Celsius and 50 milliamps (mA) per millimeter (mm).