Physical degradation of GaN HEMT devices under high drain bias reliability testing

The AlGaN/GaN heterostructure HEMTs were epitaxially grown using MOCVD on semi-insulating SiC substrates. Standard III–V commercial production processing technology was used to fabricate the devices, which were then subjected to stress under accelerated DC life-tests with base-plate temperatures of 82, 112, and 142 C. Drain bias of 40 V and time-zero drain current of 250 mA/mm were applied. TEM samples were prepared via the lift-out technique using a focused ion beam (FIB). TEM analysis revealed that electrically degraded devices always contain a pit-like defect next to the drain in the top AlGaN layer. It has been found that the degree of the defect formation strongly correlates to drain current (IDmax) degradation. 2009 Elsevier Ltd. All rights reserved.