Out-diffusion of Pd as a potential degradation mechanism in GaN HEMTs with Ni-Pd-Au Schottky contacts

Yongkun Sin; Dmitry Veksler; William Hubbard; Miles Brodie; Scott Sitzman; Zachary Lingley

doi:10.1117/12.2543432

27 February 2020 Out-diffusion of Pd as a potential degradation mechanism in GaN HEMTs with Ni-Pd-Au Schottky contacts

Yongkun Sin, Dmitry Veksler, William Hubbard, Miles Brodie, Scott Sitzman, Zachary Lingley

Proceedings Volume 11280, Gallium Nitride Materials and Devices XV; 112801I (2020) https://doi.org/10.1117/12.2543432
Event: SPIE OPTO, 2020, San Francisco, California, United States

Abstract

GaN high electron mobility transistors (HEMTs) on SiC substrates are produced for both commercial and defense applications that require high voltage, high power, and high efficiency operation. Although leading GaN HEMT manufacturers have reported excellent RF power characteristics and encouraging reliability, long-term reliability in the space environment remains a major concern due to unknown degradation mechanisms. For the present study, we investigated stressed/degraded RF GaN HEMTs using micro-analytical techniques. Our RF AlGaN-GaN devices grown on SiC substrate had a Ni-Pd-Au Schottky gate length of 0.25 μm, a total gate width of 6 × 150 μm periphery, and a field plate. First, we performed DC bias-temperature stress tests on GaN HEMTs and some GaN HEMTs were thermally stressed as monitor samples. Second, we employed focused ion beam (FIB) to prepare TEM cross sections from degraded and monitor devices for defect analysis using a high resolution TEM. Defects containing highly Pd-enriched features were found at the edge of the drain side of the gate. We present our detailed analysis results including our understanding on the out-diffusion of Pd as a potential degradation mechanism in our RF devices.

Citation Download Citation

Yongkun Sin, Dmitry Veksler, William Hubbard, Miles Brodie, Scott Sitzman, and Zachary Lingley "Out-diffusion of Pd as a potential degradation mechanism in GaN HEMTs with Ni-Pd-Au Schottky contacts", Proc. SPIE 11280, Gallium Nitride Materials and Devices XV, 112801I (27 February 2020); https://doi.org/10.1117/12.2543432

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