Proposed GaN HFET current collapse mechanism

The root cause of "current collapse" associated with GaN HFET subjected to high power or pulsed operation condition is discussed. Removal of polarization induced, mobile holes from the surface of the heterojunction transistor, accompanied by the removal of equal number of electrons in the 2DEG is described as the basic mechanism for device performance degradation. Approaches to alleviate the unique reliability issue of one of the most promising, nitride-based, microwave power transistor through reduction, or prevent the drainage of mobile holes are discussed.