Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates
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 <inline-formula> <tex-math notation="LaTeX">...
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2024-01-01
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| author | Pieter Cardinael Sachin Yadav Bertrand Parvais Jean-Pierre Raskin |
| author_facet | Pieter Cardinael Sachin Yadav Bertrand Parvais Jean-Pierre Raskin |
| author_sort | Pieter Cardinael |
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| description | 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 <inline-formula> <tex-math notation="LaTeX">$({\rho }_{eff})$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">${\rho }_{eff}$ </tex-math></inline-formula> degradation under stressed conditions remains unclear. In this paper, we show that up to 50% variation in <inline-formula> <tex-math notation="LaTeX">${\rho }_{eff}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$2^{\mathrm{ nd}}$ </tex-math></inline-formula> 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 (<inline-formula> <tex-math notation="LaTeX">$\text{V}_{\text {FB}}$ </tex-math></inline-formula>) 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. |
| format | Article |
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| institution | Kabale University |
| issn | 2168-6734 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IEEE |
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| series | IEEE Journal of the Electron Devices Society |
| spelling | doaj-art-f03022e5913c448999ae5a41e212c7442025-01-28T00:00:41ZengIEEEIEEE Journal of the Electron Devices Society2168-67342024-01-011232233010.1109/JEDS.2024.338617010495002Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si SubstratesPieter Cardinael0https://orcid.org/0000-0002-8603-2497Sachin Yadav1https://orcid.org/0000-0003-4530-2603Bertrand Parvais2https://orcid.org/0000-0003-0769-7069Jean-Pierre Raskin3https://orcid.org/0000-0001-9715-9699Institute of Information and Communication Technologies, Université catholique de Louvain, Louvain-la-Neuve, Belgiumimec, Leuven, Belgiumimec, Leuven, BelgiumInstitute of Information and Communication Technologies, Université catholique de Louvain, Louvain-la-Neuve, BelgiumUnderstanding 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 <inline-formula> <tex-math notation="LaTeX">$({\rho }_{eff})$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">${\rho }_{eff}$ </tex-math></inline-formula> degradation under stressed conditions remains unclear. In this paper, we show that up to 50% variation in <inline-formula> <tex-math notation="LaTeX">${\rho }_{eff}$ </tex-math></inline-formula> 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 <inline-formula> <tex-math notation="LaTeX">$2^{\mathrm{ nd}}$ </tex-math></inline-formula> 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 (<inline-formula> <tex-math notation="LaTeX">$\text{V}_{\text {FB}}$ </tex-math></inline-formula>) 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.https://ieeexplore.ieee.org/document/10495002/C-doped buffer layereffective resistivityGaN-on-Si substrateharmonics distortionRF characterizationtraps |
| spellingShingle | Pieter Cardinael Sachin Yadav Bertrand Parvais Jean-Pierre Raskin Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates IEEE Journal of the Electron Devices Society C-doped buffer layer effective resistivity GaN-on-Si substrate harmonics distortion RF characterization traps |
| title | Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates |
| title_full | Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates |
| title_fullStr | Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates |
| title_full_unstemmed | Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates |
| title_short | Effect of Buffer Charge Redistribution on RF Losses and Harmonic Distortion in GaN-on-Si Substrates |
| title_sort | effect of buffer charge redistribution on rf losses and harmonic distortion in gan on si substrates |
| topic | C-doped buffer layer effective resistivity GaN-on-Si substrate harmonics distortion RF characterization traps |
| url | https://ieeexplore.ieee.org/document/10495002/ |
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