Raman characterization of SiNx deposition on undoped Al0.48In0.52As and n+ Ga0.47In0.53As layers for InP high electron mobility transistor applications

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Abstract
Effects of SiNx deposition on undoped Al0.48In0.52As and n+ Ga0.47In0.53As bulk layers grown on InP substrate have been investigated using Raman spectroscopy. No significant effects induced from the dielectric deposition have been observed in the Al0.48In0.52As material, whatever the thickness and the temperature deposition used in the technological process. On the contrary, slight modifications of the Raman spectra have been noticed for n+ Ga0.47In0.53As samples passivated at 300 °C. The observed differences have been interpreted as a surface potential decrease of 0.15 V and correlated to electrical measurements made on InP-based high electron mobility transistors. In this case, an increase of the maximum drain current has been observed in agreement with the surface potential change deduced from Raman experiments.