Metal-oxide-semiconductor tunneling photodiodes with enhanced deep depletion at edge by high-k material

Metal-oxide-semiconductor (MOS) photodetector with the high-k material enhanced deep depletion at edge was demonstrated. The mechanism of saturated substrate injection current in MOS capacitor was adopted. By building HfO2 based devices that with the direct observation of the enhanced edge charge collection efficiency due to fringing field effect in inversion, we are able to show a photodetector with 3000 times (ratio of photocurrent to dark current) improvement in sensitivity than the conventional SiO2 based tunneling photodiodes (approximate 100 times) in the visible.