High performance geiger photodiodes in a 0.18-µm feature size CMOS technology

Using an advanced CMOS process, an improved Geiger photodiode (GPD) element is realized as the detection efficiency is increased with a decrease in noise terms. Using an inverted geometry, the surface doping concentration and diode volume are small. The GPD shows a reduction of at least a factor of ten in the dark count rate compared to a previous CMOS GPD design, due to the limited volume within the GPD active region and low doping profile. The inverted design allows for the electrical field to approach the surface of the diode enabling better UV detection, the detection efficiency is increased by more than a factor of roughly two at 380 nm compared to the previous design. The diode shows an over all increase of a factor 1.3 compared to the previous design. Due to the large operating bias, the after pulse multiplier is no larger than a factor of 1.5 larger than the previous design. Even with higher after pulsing, the diode will exhibit a significant improvement over previous solid-state photomultiplier designs using previous GPDs, since a larger Geiger probability, with a overall improvement in the detection efficiency, is accessible with a significantly lower dark current.