Polarization effects in ferroelectric gate AlGaN/GaN High Electron Mobility Transistors

• Published in: 2020 32nd International Symposium on Power Semiconductor Devices and ICs (ISPSD) pp. 329 - 332
• Main Authors: Zhou, R., Li, L., Zhao, W., Liao, Z., Nguyen, M. D., Nunnenkamp, M., Houwman, E. P., Koster, G., Rijnders, A. J. H. M., Gravesteijn, D. J., Hueting, R. J. E.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-09-2020
• Subjects: 2DEG; AlGaN/GaN HEMTs; Analytical models; ferroelectric gate; HEMTs; Logic gates; Polarization effect; PZT; Resistance; Threshold voltage; Wide band gap semiconductors; Zirconium
• ISSN: 1946-0201
• DOI: 10.1109/ISPSD46842.2020.9170173

The impact of polarization effects induced by a ferroelectric layer on the on-state performance of ferroelectric gate AlGaN/GaN HEMTs has been studied by using experiments and extensive TCAD simulations. Stress-free and high quality crystalline (111) lead-zirconate-titanate (\mathrm{P}\mathrm{b}(\mathrm{Z}\mathrm{r}_{x}\mathrm{T}\mathrm{i}_{1-x})\mathrm{O}_{3} or PZT) films on top of GaN have been successfully obtained by adopting a single magnesium-oxide (MgO) monolayer as a buffer layer. By adjusting the zirconium composition (x) of PZT, solely the spontaneous polarization in PZT is varied. In addition a onedimensional electrostatic model has been derived showing the impact of the polarization in the ferroelectric gate on the 2DEG sheet density and threshold voltage (V_{\mathrm{T}\mathrm{H}}), which is in good agreement with TCAD simulations. The experimental data show for x=0.20 a minimum on-resistance (R_{\mathrm{O}\mathrm{N}}) of \sim 9.7\mathrm{k}\Omega and for x=0.52 a minimal V_{\mathrm{T}\mathrm{H}} of ~-3.3V. The results are important for providing a guide line to optimize ferroelectric gate AlGaN/GaN HEMTs.