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| Main Authors: | , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2603.27133 |
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| _version_ | 1866917460124368896 |
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| author | Dastider, Ankan Ghosh Grupen, Matt Miller, Nicholas C. Rakheja, Shaloo |
| author_facet | Dastider, Ankan Ghosh Grupen, Matt Miller, Nicholas C. Rakheja, Shaloo |
| contents | Hot longitudinal optical (LO) phonons in GaN have recently been identified as a major factor degrading the DC performance of GaN high-electron-mobility transistors (HEMTs) by 30-60%, despite their ultrafast decay. However, their impact on large-signal RF performance, particularly RF linearity, remains poorly understood. Using full-band transport simulations of a fabricated GaN HEMT, we show that even ultrafast LO phonons with a lifetime of 30 fs degrade the output 1-dB compression point and the third-order output intercept power by ~3 dB compared to the case without LO phonon heating. Furthermore, our analysis reveals that improvements in transconductance ($g_\textrm{m}$) flatness do not necessarily translate into improved RF linearity because multiple nonlinear mechanisms contribute to the transistor response, and their combined effect cannot be captured by $g_\mathrm{m}$ flatness alone. This work clarifies a persistent ambiguity in the literature regarding using $g_\mathrm{m}$ flatness as a proxy for RF linearity and establishes intrinsic phonon-induced limits on the RF performance of GaN HEMTs. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_27133 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Hot LO Phonon-Induced RF Nonlinearity in GaN High-Electron-Mobility Transistors Dastider, Ankan Ghosh Grupen, Matt Miller, Nicholas C. Rakheja, Shaloo Applied Physics Hot longitudinal optical (LO) phonons in GaN have recently been identified as a major factor degrading the DC performance of GaN high-electron-mobility transistors (HEMTs) by 30-60%, despite their ultrafast decay. However, their impact on large-signal RF performance, particularly RF linearity, remains poorly understood. Using full-band transport simulations of a fabricated GaN HEMT, we show that even ultrafast LO phonons with a lifetime of 30 fs degrade the output 1-dB compression point and the third-order output intercept power by ~3 dB compared to the case without LO phonon heating. Furthermore, our analysis reveals that improvements in transconductance ($g_\textrm{m}$) flatness do not necessarily translate into improved RF linearity because multiple nonlinear mechanisms contribute to the transistor response, and their combined effect cannot be captured by $g_\mathrm{m}$ flatness alone. This work clarifies a persistent ambiguity in the literature regarding using $g_\mathrm{m}$ flatness as a proxy for RF linearity and establishes intrinsic phonon-induced limits on the RF performance of GaN HEMTs. |
| title | Hot LO Phonon-Induced RF Nonlinearity in GaN High-Electron-Mobility Transistors |
| topic | Applied Physics |
| url | https://arxiv.org/abs/2603.27133 |