Ultra-high sensitivity photodetector arrays with integrated amplification and passivation nano-layers

Miniaturized field-deployable spectrometers used for rapid analysis of chemical and biological substances require high-sensitivity photo detectors. For example, in a Raman spectroscopy system, the receiver must be capable of high-gain, low-noise detection performance due to the intrinsically weak signals produced by the Raman effects of most substances. We are developing a novel, high-gain hetero-junction phototransistor (HPT) detector which employs two nano-structures simultaneously: a 3-30 nm passivation layer that enables micron-sized devices, large-scale integration and low-cost products; and a 50-65 nm amplification layer that offers high sensitivity with 1,000x amplification and zero avalanche access noise. We report preliminary tests on single pixels, validating the design target of >1,000 Ampere/Watt responsivity at the near infrared wavelength of 1550nm, which is 100 times more sensitive than InGaAs avalanche photodiodes, the most sensitive commercially available photo-detector in this wavelength range, under their normal operation conditions. Integrated into a detector array, this technology has application for Laser-Induced Breakdown Spectroscopy (LIBS), pollution monitoring, pharmaceutical manufacturing by reaction monitoring, chemical & biological transportation safety, and bio-chemical analysis in planetary exploration.