Low-dark-current, high-responsivity indium-doped tin oxide/Au/n-Ge Schottky photodetectors for broadband 800–1650 nm detection

This work presents a new germanium Schottky photodetector, in which an ultrathin Au interlayer serving as a barrier enhancement layer is inserted between the indium-doped tin oxide (ITO) and n-Ge contact. A well-behaved ITO/Au (5 nm)/n-Ge Schottky photodetector is obtained, which exhibits a lower dark current density (∼300 times) and higher responsivity than ITO/n-Ge control devices. This low-dark-current device spontaneously provides high sensitivity for near-infrared wavelength detection, realizing substantial responsivity for wavelengths from 800 to 1650 nm. These ITO/Au/n-Ge photodetectors are quite useful for detecting wavelengths covering the optical communication bands with low cost and high efficiency.