Understanding and mitigation of substrate RF losses and signal distortion are critical to enable high-performance GaN-on-Si front-end-modules. While the origin of RF losses and consequently a decreased effective substrate resistivity ρeff in GaN-on-Si substrates is now understood to be diffusion of Al and Ga atoms into the silicon substrate during III-N growth, the effect of upper III-N buffer layers on the ρeff degradation under stressed conditions remains unclear. In this paper, we show that up to 50% variation in ρeff at 2 GHz can take place over more than 1,000 s when the substrate is stressed at 50 V. Additionally, Coplanar Wave Guide (CPW) large-signal measurements under the same experimental conditions show a variation of 2nd harmonic power of up to 5dB. A thermally activated stress and relaxation behavior shows the signature of traps which are present in the C-doped layers. With the help of a simplified TCAD model of the GaN-on-Si stack, we link this behavior to slow charge redistribution in the C-doped buffer continuously modifying the flat-band voltage (VFB) of the Metal-Insulator-Semiconductor (MIS) structure. Free carrier transport across the buffer is shown to have the greatest contribution on the large time constants, highlighting the importance of vertical transport paths in GaN-on-Si stacks.
Cardinael, P, Yadav, S, Parvais, B & Raskin, J-P 2024, 'Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates', IEEE Journal of the Electron Devices Society, vol. 12, pp. 322-330. https://doi.org/10.1109/JEDS.2024.3386170
Cardinael, P., Yadav, S., Parvais, B., & Raskin, J.-P. (2024). Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates. IEEE Journal of the Electron Devices Society, 12, 322-330. https://doi.org/10.1109/JEDS.2024.3386170
@article{b3cde9732c1d42598a9e41ad43dcb58c,
title = "Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates",
abstract = "Understanding and mitigation of substrate RF losses and signal distortion are critical to enable high-performance GaN-on-Si front-end-modules. While the origin of RF losses and consequently a decreased effective substrate resistivity ρeff in GaN-on-Si substrates is now understood to be diffusion of Al and Ga atoms into the silicon substrate during III-N growth, the effect of upper III-N buffer layers on the ρeff degradation under stressed conditions remains unclear. In this paper, we show that up to 50% variation in ρeff at 2 GHz can take place over more than 1,000 s when the substrate is stressed at 50 V. Additionally, Coplanar Wave Guide (CPW) large-signal measurements under the same experimental conditions show a variation of 2nd harmonic power of up to 5dB. A thermally activated stress and relaxation behavior shows the signature of traps which are present in the C-doped layers. With the help of a simplified TCAD model of the GaN-on-Si stack, we link this behavior to slow charge redistribution in the C-doped buffer continuously modifying the flat-band voltage (VFB) of the Metal-Insulator-Semiconductor (MIS) structure. Free carrier transport across the buffer is shown to have the greatest contribution on the large time constants, highlighting the importance of vertical transport paths in GaN-on-Si stacks.",
author = "Pieter Cardinael and Sachin Yadav and Bertrand Parvais and Jean-Pierre Raskin",
note = "Publisher Copyright: {\textcopyright} 2013 IEEE.",
year = "2024",
doi = "10.1109/JEDS.2024.3386170",
language = "English",
volume = "12",
pages = "322--330",
journal = "IEEE Journal of the Electron Devices Society",
issn = "2168-6734",
publisher = "Institute of Electrical and Electronics Engineers",
}