Cardinael, P., Yadav, S., Hahn, H., Zhao, M., Banerjee, S., Esfeh, B. K., Mauder, C., Sullivan, B. O., 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. ArXiv. https://doi.org/10.48550/arXiv.2404.02707

@techreport{c5822bf42bca4a268c0f76fb33ccda2f,
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 HEMT 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 MOCVD-grown AlN/Si structures is presented. The presence of a \$\textbackslash{}text\{SiC\}\_\textbackslash{}text\{x\}\textbackslash{}text\{N\}\_\textbackslash{}text\{y\}\$ interfacial layer is revealed and its importance for RF losses is shown. Through C-V and I-V characterisation, 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 TMAl predose is shown to allow precise tuning of the C composition and, consequently, the resulting interface charge. Notably, a linear relationship between predose and 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 \$D\_\{it\}\$ (\$\textbackslash{}sim 2\textbackslash{}times 10\textasciicircum{}\{12\}\$ cm\$\textasciicircum{}\textbackslash{}text\{-2\}\$) for such compensated samples is observed and can contribute to low RF loss. An exceptionally high effective resistivity of above 8 k\$\textbackslash{}Omega\textbackslash{}cdot\$cm is achieved, corresponding to an RF loss below 0.3 dB/mm at 10 GHz. ",
keywords = "physics.app-ph",
author = "Pieter Cardinael and Sachin Yadav and Herwig Hahn and Ming Zhao and Sourish Banerjee and Esfeh, \{Babak Kazemi\} and Christof Mauder and Sullivan, \{Barry O\} and Uthayasankaran Peralagu and Anurag Vohra and Robert Langer and Nadine Collaert and Bertrand Parvais and Jean-Pierre Raskin",
note = "The following article has been accepted for publication in Applied Physics Letters. After it is published, it will be found at https://pubs.aip.org/aip/apl",
year = "2024",
month = apr,
day = "3",
doi = "10.48550/arXiv.2404.02707",
language = "English",
publisher = "ArXiv",
type = "WorkingPaper",
institution = "ArXiv",
}