Plasma diagnostics and device properties of AlGaN/GaN HEMT passivated with SiN deposited by plasma-enhanced chemical vapour deposition

8 pages, 10 figures.-- PACS: 52.70.-m; 81.65.Rv; 81.15.Gh; 52.77.Dq; 52.75.-d, 85.30.TvIn this work, silicon nitride thin films have been deposited by plasma enhanced chemical vapour deposition on both silicon samples and AlGaN/GaN high electron mobility transistors (HEMT) grown on sapphire substrates. Commercial parallel-plate RF plasma equipment has been used. During depositions, the dissociation rates of SiH4 and NH3 precursors and the formation of H2 and N2 have been analysed by mass spectrometry as a function of the NH3/SiH4 flow ratio and the RF power applied to the plasma reactor. Afterwards, the properties of the films and the HEMT electrical characteristics have been studied. Plasma composition has been correlated with the SiN deposition rate, refractive index, H content and the final electric characteristics of the passivated transistors.This work was supported in part by the KORRIGAN project (EDA—04/102.052/032 CA 2157v7) and in part by the projects ICTS-2007-05, MAT2007-65965, FIS 2007-61686 and CSD2009-00038 of the MICINN of Spain.Peer reviewe