LED's and opto-electronic devices

Thanks to the close match of the lattice constant and thermal expansion coefficient of germanium and III-V compounds, germanium is one of the materials of choice for the production of high brightness LEDs. The germanium substrate serves either as a carrier for thin-film LEDs or as a growth substrate in various types of surface-mount LEDs. Compared to gallium arsenide, germanium is recyclable, which is important for backside thinning and permits more efficient and environmental use of the material overall.