The notable properties of germania or germanium dioxide (GeO2) are its high refractive index and low optical dispersion; these make it especially useful for lenses (Achromatic Lens System For Ultraviolet Radiation With Germanium Dioxide Glass (2000)), and the core part of optical fibres (Germania-Containing Optical Waveguide (1976)).
Germanium antimony telluride (GeSbTe) is a phase change material (Germanium Antimony Telluride Materials And Devices Incorporating Same (2013)), used for its optic properties, such as that used in rewriteable DVDs.
Silicon germanium alloys are rapidly becoming an important semiconductor material for high-speed integrated circuits (Process For Manufacturing Silicon-Germanium Alloys (1990). Circuits utilizing the properties of Si-SiGe junctions can be much faster than those using silicon alone (Photoconductive Member Of A Ge-Si Layer And Si Layer (1986)).
Solar panels are a major use of germanium. Germanium is a component of the substrate of the wafers for high-efficiency multijunction photovoltaic cells for space and terrestrial applications (Multijunction Photovoltaic Cells And Panels Using A Silicon Or Silicon-Germanium Active Substrate Cell For Space And Terrestrial Applications (2002)).
Germanium-on-insulator (GeOI) substrates are seen as a potential replacement for silicon on miniaturized chips (Method Of Manufacturing A Germanium-On-Insulator Substrate (2017)).
CMOS circuits based on GeOI substrates have been reported (Method Of Growing Germanium Epitaxial Film On Insulator For Use In Fabrication Of Cmos Integrated Circuit (2006)).
Other uses of germanium in electronics include phosphors in fluorescent lamps. Germanium dioxide is also used as a catalyst for ester polymerisation (Germanium-Activated Phosphor (1958), and Process Of Using Germanium Dioxide As A Polyester Condensation Catalyst (1968)).
Due to the similarity between silica (SiO2) and germanium dioxide (GeO2), the silica stationary phase in some chromatography columns can be replaced by GeO2: Separation Column With Germania-Based Sol-Gel Stationary Phase (2012).