Responsivity improvement for short wavelenghts using full-gated PIN lateral SiGe diode

Lateral PIN diodes can be used as photo-detectors in a wide wavelength range, including blue and UV radiation. Unlike vertical devices, lateral diodes can have depletion regions very close to the device surface, where the absorption of low-wavelengths radiation takes place. Due to this proximity to the surface, a MOS gate can control the charge density inside this region, allowing responsivity control. This work reports experimental results of gated PIN photodetectors designed and fabricated in a SiGe CMOS process. It was shown that, when the photodiode is illuminated with short wavelength radiation, the gate bias becomes very effective in terms of responsivity control, with up to 163% raise at UV. Indeed, based on the penetration-depth-dependent absorption of different wavelegths, our device has shown good color selective responsivity.