Quantum Structures for Multiband Detection

Gamini Ariyawansa

Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303

Quantum dot, dots-in-a-well, and Homojunction Interfacial Workfunction Internal Photoemission (HIWIP) infrared detectors, designed for multiband detection, were studied. A correlation between the InGaAs well width of InAs/InGaAs quantum dots-in-a-well (DWELL) detector and the peak detection wavelength was obtained. A novel quantum dot detector with double tunneling barriers, where photoexcited carriers are selectively collected from InGaAs quantum dots through resonant tunneling, was demonstrated to operate at room temperature. The operating temperature was pushed to 300 K by inhibiting dark current using AlGaAs blocking barriers placed right before contacts. A GaAs based HIWIP NIR/MIR-FIR dual band detector was demonstrated. The inter- and intra-band operation of this device, giving rise to NIR and FIR detection respectively, are due to photoemission of careers from a moderately doped GaAs barrier region, and from a heavily doped emitter region respectively. Tailoring the NIR threshold wavelength from NIR to UV, using different material bases or changing the alloy fraction in heterostructure infrared detectors, will be studied. These multiband detectors can be used in applications such as environmental monitoring, medical diagnosis, battlefield-imaging, space astronomy applications, mine detection, and remote-sensing.

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