Germanium on Glass: A Novel Platform for Light-Sensing Devices

Using layer transfer and wafer bonding followed by epitaxial regrowth, we design, realize, and characterize a novel generation of Germanium-on-Glass (GoG) near-infrared light sensors. In particular, we demonstrate GoG p-n junction photodetectors and GoG solar cells. In terms of performance, GoG junctions compare well with Germanium (Ge) structures on either Ge or Si. The photodiodes show a minimum dark current density of 50 μA/cm² at 1 V reverse voltage and a maximum sensitivity of 280 mA/W at 1.55 μm and 5 V bias; the solar cells exhibit conversion efficiencies as high as 2.41% and fill factors of 53%, similar to structures grown on crystalline Ge substrates.