Dalapati, P., Arulkumaran, S., Mani, D., Li, H., Xie, H., Wang, Y., & Ng, G. I. (2024). Change of chemical bonding properties at SiNx/GaN/AlGaN interface with SiH4 flow rate and its impact on the carrier transport properties of MIS-diodes. Materials Science and Engineering: B, 307, 117503. https://doi.org/10.1016/j.mseb.2024.117503
Abstract:
The understanding of the properties of silicon nitride (SiNx) deposited by plasma-enhanced chemical vapor deposition (PECVD) is crucial as this layer is widely used for gate dielectric and surface passivation. In the PECVD system, the passivation quality can be altered substantially with SiH4 flow rate. Therefore, in the present work, variation of chemical structures at the SiNx/GaN interface with SiH4 flow rate and its impact on the charge transport mechanisms of metal–insulator-semiconductor (MIS) diodes have been systematically investigated. X-ray photoelectron spectroscopy results suggest that the trap states related to Ga-O and N-H bonds decline when SiH4 flow rate increases from 55 to 85 sccm, leading to a reduction of surface-electron trapping and an improvement in surface passivation quality. The same observation can also be confirmed using Fourier transform infrared spectroscopy measurements. The leakage current and interface trap density of MIS-diode with 85 sccm SiH4 flow rate deposited SiNx are significantly lower than that of MIS-diode with 55 sccm SiH4 flow rate deposited SiNx. Interestingly, after passivation, the density of slow traps is suppressed largely and we achieved a minimum interface trap density of 1.57 × 1012 cm−2.eV−1 which helps to suppress three orders of magnitude lower leakage current compared to the conventional Schottky diode.
License type:
Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)
Funding Info:
This research / project is supported by the Agency for Science, Technology and Research - RIE2025 Manufacturing, Trade, and Connectivity Programmatic Fund
Grant Reference no. : M21K6b0134