Germanium waveguide for optical interconnects in very large scale integrated optics

摘要

Abstract: The Fourier Transform Infrared (FTIR) absorption spectrum for the range of 500 to 4000 cm$+$MIN@1$/ wavenumbers was measured for several Ge films deposited on GaAs using ultra high vacuum E-beam deposition at various substrate temperatures ranging from room temperature (RT) to 500$DGR@C. Using transmission electron microscopy, we show that Ge films deposited at room temperature and 100$DGR@C on a (100) GaAs surface that did not have the oxides removed are amorphous while those deposited at 100$DGR@C with the oxide removed are crystalline, but are highly defective. Secondary ion mass spectroscopy (SIMS) measurements show that the amorphous films at RT contain more than two orders of magnitude more oxygen than the films deposited at 100$DGR@C or a single crystal film deposited at 400$DGR@C. The oxygen-18 diffusion studies definitively show that the excess oxygen in the amorphous films percolates in from the atmosphere. SIMS studies further reveal that thermally removing the GaAs substrate surface oxide or depositing a Au film on top of the Ge film has little effect on the incorporation of oxygen.!9