Uncooled Semiconductor Detectors for IR to UV Remote Sensing

Results are presented on three different approaches which show room temperature infrared sensing. The first approach is based on transitions from the light/heavy hole to the split-off band in p-doped GaAs/AlGaAs heterostructure showing a response threshold of 3.4 mu m and operating LIP to a temperature of 330 K. The peak responsivity at 2.5 mu m was similar to 1.5 mA/W with a D* of 2.3x10(6) Jones at 330 K. The split-off threshold can be extended to longer wavelengths by using different materials. The second approach is based oil capacitance variations in a quantum dot (QD) embedded dielectric medium. The incident IR photons induce charge separation inside the QDs and effectively change the dielectric properties varying the capacitance. Initial devices using PbS and ZnO QDs in paraffin have shown detection at 3 10 K in both the visible-NIR range. Using other materials and sizes of dots the range can be tailored for applications in other ranges including the UV range. The third approach uses tunneling quantum dot infrared photodetector (TQDIP) structures providing multi-color characteristics, and bias dependent wavelength selectivity. Here a tunneling barrier is used to block the dark current while permitting the photocurrent to pass through due to resonance effects. A preliminary TQDIP detector showed room temperature response at 6 and 17 pill with responsivity of 75 rnA/W and 150 rnA/W respectively. The peak detectivity of similar to 10(7) Jones was reported for both peaks.