Thin germanium nitride films grown by thermal reaction process

Thin films have been grown on 〈111〉 germanium by thermal nitridation. The surface morphology, composition, thickness, and refractive index of the films have been investigated. Compositional analysis was performed by electron beam x-ray microanalysis which indicates that the films contain oxygen as well as nitrogen and have a nitrogen to oxygen ratio on the order of 2.5:1. Film thickness and refractive index were determined by ellipsometry. The thicknesses ranged from 60 to 150 Å, and the refractive indices ranged from 1.5 to 2.3 depending on growth parameters. A universal chart for evaluating the thickness and refractive index of dielectric films on germanium from the ellipsometric parameters ψ and Δ is also presented.