Novel "Quantum Dots" Infra-Red Detector

Multispectral infrared (IR) detector arrays have tremendous potential application in both military and civil application, such as surveillance and target discrimination based on emissivity, law enforcement, environmental monitoring, etc. At present, many high performance IR detectors, especially longwave IR (LWIR) detectors, are made from materials (HgCdTe) that are quite difficult to make with acceptable homogeniety. There are materials, whose growth technologies (III/V semiconductors) are more mature and can provide very accurate control of compositions and homogeneity. Consequently, it is usually desirable to develop IR photodetectors from such materials. One major drawback of these IR detectors is that they cannot detect normally incident light due to the restriction of selection rules. Although there are many approaches to circumventing this problem, they still suffer from complexity of device design and poor performance. In contrast, "quantum dot" IR detectors (QD's) lack these restrictions. Theoretical analysis has shown that the QD infrared photodetector (QDIP) should have a superior performance to others. Absorption in the midwave & longwave IR regions has been experimentally observed. However, no one has ever demonstrated a QD IR detector. Researchers at Arizona State University have developed a novel approach, which not only provides normal-incidence IR light detection but also high quantum efficiency, very narrow response linewidth, and wide wavelength coverage. The beauty of this invention is that one does not need highly uniform QD's. Additionally, by simply changing aspects of the design, the wavelength of the peak response can easily be altered.