Dual-band Photodetectors

Single-chip integrated solar-blind UV/IR high-temperature photo detectors:

Fires produce emissions ranging from UV to IR bands.  Such emissions can only be detected over the wide-range of ambient light background, by fast multi-range optical detectors allowing time- and spectrally-resolved measurements in particular optical regions.  As a result, the spectral range, as well as the detector speed, spatial resolution and alignment become critical for fast fire detection, as well as for avoiding costly false alarms.  Currently used photo-multiplier tubes (PMTs) have high sensitivity, however, they are bulky, require high voltage operation, have low mechanical and temperature strength, and cannot be easily integrated into current fire detectors.  In addition, the recently developed dual-band photodetectors that are composed of discrete UV and IR solid state components are bulky, not capable of detecting the multi-band optical signal with high spatial resolution, and are not suitable for networking.

IMS has developed a miniature, chip-based dual-color, high-temperature, visible- or even solar-blind optical sensor system that would allow for fast and false-alarm free fire-detection and recognition, thus providing a fast and reliable response in separated UV and IR bands with high spatial resolution.  The device is based on advanced technological capabilities of group III-nitride materials that are superior for advanced UV detector fabrication, due to their wide direct band gap along with high thermal, chemical, mechanical, and radiation tolerance. Measurements performed in our laboratory on GaN/InGaN-based heterostructure chips, show that they can be operated at temperatures over 300°C without internal or external cooling.

Dual-band visible- and solar-blind UV/IR photodetectors integrated in a single package exhibited peak responsivities of the dual-band photodetectors are 0.0038  A/W and 0.055 A/W at wavelengths of 349 nm and 1000 nm respectively, as shown in the figure below.

 

In addition, our technology renders possible fire imaging (precise localization of fire sources) and fire characterization (precise analysis of combustible yielding proper choice of fire inhibitor to be used).  This technological edge will allow the everyday firefighter to acquire precise and valuable information about the problem at hand and take proper measures for control and containment.  The projected low cost devices will change the power equation in the way fires are prevented, detected and controlled.