Integrated phototransistors in a CMOS process for optoelectronic integrated circuits

This work presents integrated pnp phototransistors built in a 0.6 μm OPTO ASIC CMOS process using a low doped epi wafer as starting material. Several phototransistors with different designs of the base and emitter area were realized and characterized. For these novel photodetectors responsivities up to 65 A/W for DC light and up to 37.2 A/W for modulated light were achieved. Other transistors reach bandwidths up to 14 MHz. Due to the used standard silicon CMOS process low-cost integration is possible. Analog and digital circuitry can be implemented together with active optical detectors. This paves the way for high performance optical sensors and cost efficient SoC devices. Typical application examples include highly sensitive optical sensors, active pixel image sensors, light barriers and optical distance measurement sensors as well as 3D cameras.