Abstract
Ellipsometric techniques were used to investigate the thin films that formed on cleaved germanium samples in air, deionised water, and 30% hydrogen peroxide. In all three cases the films were less than 100 Å in thickness. The films formed in air and water had a refractive index of 1.63±0.02 which is close to that of glassy GeO2. An increase of refractive index to about 1.74 was observed when the samples were immersed in a solution of 30% H2O2. The thickness of this film (18Å) remained relatively constant in a period of 5 min to 6 h. The film is attributed to a layer of Ge(OH)2 2+ surface complexes, and a thick reaction envelope of metagermanic acid (H2GeO3). After rinsing surfaces covered with glassy GeO2 with a 48% HF solution, the original oxide was removed; however, within 5 min a 50Å thick film of glassy GeO2 had formed.
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Ehman, M.F., Vedam, K., White, W.B. et al. Characterisation of thin surface films on germanium in various solvents by ellipsometry. J Mater Sci 6, 969–973 (1971). https://doi.org/10.1007/BF00549947
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DOI: https://doi.org/10.1007/BF00549947