Ge-on-glass detectors

A single crystalline thin film of Ge on glass is fabricated using wafer bonding and smart cut. A simple metal-insulator-semiconductor detector is demonstrated for visible light and telecommunication wavelength. The implantation damage of separated Ge film bonded on glass is removed by chemical etching, and the surface roughness is reduced from 14 to 4 nm. The defect removal reduces the dark current by a factor of 30 and increases the responsivity by a factor of 1.85 at visible wavelength. The responsivity of 0.27 A/W at 1.3 mu m wavelength for an unetched device does not increase after damage removal due to the decrease of the absorption layer thickness.