Fabrication of low-RF loss GaN-on-Si high electron mobility transistor stacks is critical to enable competitive front-end-modules for 5G and 6G applications. The main contribution to RF losses is the interface between the III-N layer and the HR Si wafer, more specifically the AlN/Si interface. At this interface, a parasitic surface conduction layer exists in Si, which decreases the substrate effective resistivity sensed by overlying circuitry below the nominal Si resistivity. However, a clear understanding of this interface with control of the parasitic channel is lacking. In this Letter, a detailed physical and electrical description of metalorganic chemical vapor deposition-grown AlN/Si structures is presented. The presence of a SiCxNy interfacial layer is revealed, and its importance for RF losses is shown. Through C-V and I-V characterization, an increase in the C concentration of this interfacial layer is linked to the formation of negative charge at the AlN/Si interface, which counteracts the positive charge present in the 0-predose limit. The variation of the TMAl predose is shown to allow precise tuning of the C composition and, consequently, the resulting interface charge. Notably, a linear relationship between the predose and the net interface charge is observed and confirmed by the fabrication of an AlN/Si sample with close to zero net charge. In addition, a higher Dit (∼ 2 × 10 12 c m − 2 ) for such compensated samples is observed and can contribute to low-RF loss. An exceptionally high effective resistivity of above 8 kΩ cm is achieved, corresponding to an RF loss below 0.3 dB/mm at 10 GHz.
Cardinael, P, Yadav, S, Hahn, H, Banerjee, S, Kazemi Esfeh, B, Mauder, C, O'Sullivan, B, Peralagu, U, Vohra, A, Langer, R, Collaert, N, Parvais, B & Raskin, J-P 2024, 'AlN/Si interface engineering to mitigate RF losses in MOCVD-grown GaN-on-Si substrates', Applied Physics Letters, vol. 125, no. 7, 072103. https://doi.org/10.1063/5.0212145
Cardinael, P., Yadav, S., Hahn, H., Banerjee, S., Kazemi Esfeh, B., Mauder, C., O'Sullivan, B., Peralagu, U., Vohra, A., Langer, R., Collaert, N., Parvais, B., & Raskin, J.-P. (2024). AlN/Si interface engineering to mitigate RF losses in MOCVD-grown GaN-on-Si substrates. Applied Physics Letters, 125(7), Article 072103. https://doi.org/10.1063/5.0212145
@article{cea610c0dd434290924d3c8049897ee1,
title = "AlN/Si interface engineering to mitigate RF losses in MOCVD-grown GaN-on-Si substrates",
abstract = "Fabrication of low-RF loss GaN-on-Si high electron mobility transistor stacks is critical to enable competitive front-end-modules for 5G and 6G applications. The main contribution to RF losses is the interface between the III-N layer and the HR Si wafer, more specifically the AlN/Si interface. At this interface, a parasitic surface conduction layer exists in Si, which decreases the substrate effective resistivity sensed by overlying circuitry below the nominal Si resistivity. However, a clear understanding of this interface with control of the parasitic channel is lacking. In this Letter, a detailed physical and electrical description of metalorganic chemical vapor deposition-grown AlN/Si structures is presented. The presence of a SiCxNy interfacial layer is revealed, and its importance for RF losses is shown. Through C-V and I-V characterization, an increase in the C concentration of this interfacial layer is linked to the formation of negative charge at the AlN/Si interface, which counteracts the positive charge present in the 0-predose limit. The variation of the TMAl predose is shown to allow precise tuning of the C composition and, consequently, the resulting interface charge. Notably, a linear relationship between the predose and the net interface charge is observed and confirmed by the fabrication of an AlN/Si sample with close to zero net charge. In addition, a higher Dit (∼ 2 × 10 12 c m − 2 ) for such compensated samples is observed and can contribute to low-RF loss. An exceptionally high effective resistivity of above 8 kΩ cm is achieved, corresponding to an RF loss below 0.3 dB/mm at 10 GHz.",
author = "Pieter Cardinael and Sachin Yadav and Herwig Hahn and Sourish Banerjee and \{Kazemi Esfeh\}, Babak and Christof Mauder and Barry O'Sullivan and Uthayasankaran Peralagu and Anurag Vohra and Robert Langer and Nadine Collaert and Bertrand Parvais and Jean-Pierre Raskin",
note = "Publisher Copyright: {\textcopyright} 2024 Author(s).",
year = "2024",
month = aug,
day = "15",
doi = "10.1063/5.0212145",
language = "English",
volume = "125",
journal = "Applied Physics Letters",
issn = "0003-6951",
publisher = "American Institute of Physics Publising LLC",
number = "7",
}