Emerging Trends in IRFPA Sensors

Significant developments have been taking place in the field of infrared sensors in recent years, to achieve higher resolution, wider spectral range, shorter response time and higher sensitivity (lower noise) in thermal imaging systems. Efforts are on to develop new technologies to produce infrared focal plane arrays (IR FPAs) with smaller pixel pitches, larger formats, higher frame rates, larger dynamic range and multicolor detection. In addition to these factors, reduction in cost, increase in IRFPA operating temperature to reduce cryogenic constraints and improvement in reliability are other driving forces for developing new technologies. Efforts in IR detector development have resulted in emergence of newer detector materials/technologies and in further device engineering of existing materials. Emergence of MEMS based IR detectors in the last decade has been one of the most significant developments in the field of uncooled detectors. Here we present a brief review of the recent developments in IRFPA technologies including detector materials and device architectures, utilized for both cooled and uncooled operations. The basic principles of various devices are briefly discussed and their performance is compared. Mercury cadmium telluride (MCT) based IR detectors have remained highest performance detectors for decades and is still the material of choice for achieving highest performance. The challenges posed by alternate technologies based on III-V compound semiconductors like InSb, GaInAs, QWIP and type-II strained layer superlattice structures are also discussed. Future trends for multi-spectral IR detectors and development of adaptive focal plane arrays is also discussed.