Abstract:
Classically gated infrared (IR) detectors have been implemented
using charge-coupled devices (CCD). Bipolar complementary
metal-oxide semiconductor (BiCMOS) technology emerged as a viable
alternative platform for development. BiCMOS technology has a number
of advantages over CCD and conventional CMOS technology, of which
increased switching speed is one. The pixel topology used in this work
is a reversed-biased diode connected heterojunction bipolar transistor.
The disadvantage of CMOS detectors is the increased readout noise
due to the increased on-chip switching compared to CCD, which degrades
dynamic range (DR) and sensitivity. This yields increased switching
speeds compared to conventional bipolar junction transistors. Sensitivity
improved from 50 mA∕W (peak) at 430 nm in CCD detectors to
180 mA∕W (peak) (or 180; 000 V∕W) at 665 nm in BiCMOS detectors.
Other CMOS IR detectors previously published in the literature showed
sensitivity values from 2750 to 5000 V∕W or 100 mA∕W. The DR also
improved from 47 and 53 dB to 70 dB. The sensitivity of conventional
CCD detectors previously published is around 53 mA∕W. The second advantage
is that detection in the near-IR band with conventional silicon integrated
technology is possible. This work has shown increased detection
capabilities up to 1.1 μm compared to Si detectors.
