Stability of the threshold voltage in fluorine-implanted normally-off AlN/GaN HEMTs co-integrated with commercial normally-on GaN HEMT technology

Fluorine ion migration in normally-off AlN/GaN HEMTs fabricated by fluorine plasma implantation technology is evidenced. Devices under test are co-integrated into the OMMIC commercial D006GH/D01GH MMIC process, providing fluorine-free normally-on HEMTs. Gate reverse bias step-stress experiment at a drain fixed voltage of 0 V, carried out as well on ones ones, shows permanent negative shift threshold Vth devices only. degradation starting VGS,stress ?8 with from V to ?0.4 = ?30 while transconductance gm and gm,max remains unchanged prior breakdown that occurred ranging between ?26 ?32 V. Since positive these induced F-ions dose position, above result suggests possible drift away 2DEG channel. A field-assisted mechanism ions proposed supported absence devices.