Off‐State Drain Leakage Current Mechanism in GaN High Electron Mobility Transistors from Thermal Storage Test

• Published in: Physica status solidi. A, Applications and materials science Applications and materials science, 2022-11, Vol.219 (21), p.n/a
• Main Authors: Mukherjee, Jayjit, Chaubey, Rupesh Kumar, Rawal, Dipendra S., Dhaka, Rajendra S.
• Format: Article
• Language: English
• Subjects: Anharmonicity; Defects; defects drain leakage; Electrical measurement; Electrical properties; Gallium nitrides; GaN high electron mobility transistors (HEMTs); Heterostructures; High electron mobility transistors; Hysteresis; Leakage current; phonon lifetime; Phonons; Recovery; Semiconductor devices; Thermal storage; thermal storage test; Thermal stress; Transconductance
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.202200211

The effect of the thermal storage test on GaN high electron mobility transistor (HEMT) is investigated in this study by observing off‐state drain leakage current and on‐state hysteresis and maximum transconductance. The recovery post thermal stress is also observed which points to native defects within the heterostructure as the leakage values after 72 hrs of recovery are measured to be one order higher than the pristine device. On‐state hysteresis recovery and off‐state drain leakage are dominated by similar defects as observed from the characteristic recovery times. Trap analysis through drain current spectroscopy reveals an additional trap level of EC – 0.83 eV from the thermal storage test. The electrical measurements are in close correlation with the E2H Raman active mode leading to reduced lifetimes (≈0.44 ps) at higher temperatures, where anharmonic phonon decay is observed following the reported Balkanski model. This gives an overall picture of the phonon‐induced defect generation from the thermal stress and the recovery from the reduced scattering probability within the material observed after 72 hrs recovery; also observed within the HEMTs from electrical characterization. The off‐state drain leakage current in GaN high electron mobility transistors (HEMTs) after a thermal storage test at 300 °C and its recovery are observed throughout 72 hrs. The thermal degradation generates a deep electron trap within the heterostructure. Raman spectroscopy on annealed bare samples give a phonon‐defect interaction at elevated temperatures correlating the high leakage current through the GaN buffer.